My Chemical-Free House

A Guide to Creating a Healthy Home

Healthy building

Hempcrete for Mold-Safe, Healthy Homes

by 1 Comment

Hemp can be used in building homes in many ways but building with hemp is very different than building with conventional construction methods.

Hempcrete can be tamped into board-formed walls, used as premade bricks, sprayed into cavities, or formed into precast panels.

It acts as insulation and as an interior and/or exterior surface, though it is not load-bearing – you still need a wood frame.

This article will review all the ways that hemp can be used to build a healthy home and is an investigation into whether it’s mold-prone.

Beautiful hempcrete salon, Hemp House Hair Salon, in British Columbia, Canada.

Before we look at the building methods closer, let’s look at what goes into hempcrete. 

What is Hempcrete Made of

1. Hemp hurd

The first ingredient of hempcrete is the aggregate, called the ‘hurd’. Hurd is the woody core of the hemp plant that remains after the plant has been stripped and the fiber sold for rope or textiles. 

The hurd is like the inside of a twig, after the bark has been stripped off, just less dense and with a hollow core. The woody core is dried and then chopped up; it looks a lot like wood mulch. 

Hemp is an organic material – meaning, it is carbon-based, just like wood (and can be mold food, just like wood). In fact, it contains more cellulose than wood does (hemp has 65-70% cellulose and wood has 40%). 

Quality is not consistent from supplier to supplier, so make sure you are buying good quality hurd before committing to a large purchase.

A good place to buy hemp hurd in the US is through Hempitecture in Idaho. 

2. Lime Binder

The lime binder contains calcium carbonate (lime) and compounds which allow it to harden – either soluble silica, alumina oxide or ferric oxide. When a lime binder can harden with the addition of water, this is called hydraulic lime. 

Hydraulic lime is readily available in the UK and France but is difficult to find in North America and often has to be imported. 

There are some binders that are produced in the US. One place to buy lime binder in the US is also through Hempitecture.

Do your research on binders before choosing one. There are binders out there that have caused mold problems where there shouldn’t have been any due to added ingredients in the binder. 

3. Water

When water is added to the hydraulic lime binder, it causes a chemical reaction (hot!) which makes it possible for it to harden once dried. 

4. Air

It feels funny to list air as an ingredient, but it’s one of the most important parts of hempcrete! 

When dried, there are many air pockets in hempcrete – both between the pieces of hemp and inside each piece of hemp. 

Air is what makes hemp a good insulator (air is the most important part of any insulation) and humidity regulator.

Water, lime, and hemp hurd. Photo courtesy of Homeland Hempcrete in North Dakota.

Put them together! 

When hemp hurd is mixed with the lime binder and water, it dries into a hard solid mass. 

Before it dries, you sprinkle it into framed molds that surround the building’s wood framing. It is then tamped down to compress it a bit, and left to dry. 

The drying time is important (between 4-8 weeks). If you don’t allow it to dry enough before removing the form work and plastering, there could be big problems (mold, staining, crumbling).

Mixing hemp and lime together: https://www.instagram.com/p/Bsn2G21hMxn/?utm_source=ig_embed&utm_campaign=loading

Building with Hempcrete: How it is Used

Hempcrete can take the place of insulation, drywall, and siding in a new wall. 

It is not a 1 to 1 replacement, though; Hempcrete can’t just be substituted for fiberglass insulation (or cellulose, etc.). Using hempcrete requires a different plan and approach compared to conventional building. 

Besides being a totally different type of material and insulation, hempcrete has a different insulation value than fiberglass or cellulose, and so it will require thicker walls.

As Insulation

This is a cross-section of a hempcrete wall – the hempcrete encapsulates the wood framing.

Hempcrete’s most important function is as insulation. The amount of insulation you require will determine how thick your wall will have to be. 

The insulation requirement (R-value requirement) depends on your local codes. The colder the climate, the thicker the wall will have to be.

Hempcrete’s R-Value is usually listed as ranging from 2-3 per inch. But some companies have claimed it can be as high as 4.8 per inch.

Photo courtesy of Hempitecture. 

As Siding (Exterior Skin)

This is the exterior wall of a hempcrete tiny house before plastering.

The outside of hempcrete can be plastered, similar to the interior. This can create more moisture risks if not done precisely or maintained properly. 

This might not be advisable in certain climates. Please find a professional to discuss what the best exterior options are for your climate.

Photo courtesy of Hempitecture.

As Interior Wall Face (Interior Skin)

This is an interior hempcrete lime-plastered wall.

Drywall is not needed when building with hempcrete. The typical interior finish is a lime render (plaster) that is applied directly to the dried hempcrete. This allows the wall to stay vapor permeable.

Anything that you add to the wall must be vapor permeable, inside and out. 

Photo courtesy of Hempitecture.

Note! 

Hempcrete is not concrete. Unlike what the name suggests, hempcrete is not made from concrete and it does not contain concrete. Even though hempcrete dries and hardens, hempcrete is not structural or load-bearing – it can’t hold up the weight of the roof. It must always be used in combination with a wood frame (or other framing material). 

Reasons to consider hempcrete

  • Hemp has a unique cellular structure that allows it to absorb and adsorb water better than other plant-based fibers. This gives it an edge in moisture management over other plant-based materials.
  • The use of a lime binder makes glues and other high VOC materials unnecessary for the wall components. 
  • It can help with maintaining healthy indoor air quality.
  • It is a fast-growing crop, so multiple harvests can be grown in one year (it is a weed, after all).
  • Hempcrete generally has very good (but not excellent) insulation value. 
  • It is very fire-resistant.
  • We know all of the ingredients in it.
  • It is vapor permeable, i.e. “breathable”- if moisture gets in, it can get out.
  • It is carbon dioxide sequestering.

Building with Hempcrete, Various Forms

1. Poured, or Formed Hempcrete

With formed (or poured) hempcrete walls, the finished walls are hardened hempcrete usually plastered with a lime render.

How it works

Forms holding hempcrete to make hempcrete walls. Photo courtesy of UK Hempcrete. Copyright UK Hempcrete

The hemp, lime binder, and water are mixed together on-site. 

Temporary wood framing aka form work (similar to when concrete is poured) is placed surrounding the structural wood frame. 

The hempcrete mix is then “poured” into place inside the wood forms and then tamped down to create a thick wall. The wood forms are left there for several weeks until the hempcrete is dried. 

Hempcrete creates a solid wall. There is no need for an interior wallboard, like drywall, just a nice lime plaster. 

The thickness of the wall will depend on how much insulation is required by code in your location, or how much insulation you want. 

Depending on location, the exterior can also just be plastered, but this should be discussed with a building science-literate professional who is familiar with your climate zone. 

Photo of hemp in exterior forms: https://www.instagram.com/p/Bsa_xkVjMMi/?utm_source=ig_embed&utm_campaign=loading

Benefits of a solid hempcrete wall

  • A good amount of thermal mass (heavy, thick walls) makes temperatures and humidity more even.
  • Using a single material means no seams and gaps like in traditional, wood-framed houses.
  • A homogeneous material makes moisture and temp management more consistent.
  • A heavyweight, formable material means less need for taping or specific air-sealing layers.
  • Building with a homogeneous material means there’s no abrupt shift in temperatures (i.e. at the sheathing), minimizing the chance of condensation.
  • Consistent vapor openness due to single material (hempcrete) makes it easier for the wall to “breathe” and dry.
  • Hempcrete works with moisture, humidity, and temperature like an experienced dance partner; conventional construction relies on keeping them away by using increasingly complex layers of barriers, insulation, boards, and tapes.

Drawbacks of a solid hempcrete wall

  • It could give you false reassurance – it still requires extensive planning and precision to avoid mold.
  • If not planned, mixed, and detailed correctly, it can become moldy .
  • The lime dust can be hazardous to breathe in and for the skin.
  • Using a framing material (i.e. wood) is still necessary. 
  • There are many unknowns about how it will perform in US climates.
  • Contractors and laborers may be inexperienced with hempcrete.
  • You will be an “early adopter”.

2. Pre-Cast Hempcrete Blocks

Precast hempcrete block. Photo courtesy of UK Hempcrete. Copyright UK Hempcrete

In order to make hempcrete thick to have enough insulation value, you can use precast hempcrete blocks on one side of the exterior wall.

The opposite side will be framed with temporary forms and be poured with hempcrete to fill the cavities and encapsulate the wood framing.

Hempcrete blocks are not load-bearing, so they will still need to be used with a wood frame. 

There is one company in Canada that is making a load-bearing block. They have not responded to my request for more information about the block. Their block is not approved for load-bearing use in the US. 

Components

Most hempcrete blocks have the same ingredients as poured walls – hemp hurd, lime binder, and water.

However, there are some that have different binders, or use a finer ground hemp, and these can cause problems. 

Always make sure you know what is in the block before committing to anything. 

Like in the picture below, the hempcrete blocks will be placed on one side of the wood-framed wall. 

A build with hemp blocks in progress: https://www.instagram.com/p/B3WirPkntVr/?utm_source=ig_embed&utm_campaign=loading

Benefits of using hempcrete block

Same as benefits for poured hempcrete, plus:

  • They are pre-dried, so you can begin applying interior plaster weeks earlier than with poured hempcrete. 
  • Faster install time.

Drawbacks of hempcrete blocks

Same as poured hempcrete, plus:

  • The cost is higher due to the labor required to cast and dry the blocks off-site.

A layer of hemp blocks complete: https://www.instagram.com/p/B3pkZnKn8uy/?utm_source=ig_embed&utm_campaign=loading

3. Sprayed-In Hempcrete

This type of hempcrete is mixed on-site, like poured hempcrete, but applied by spraying rather pouring into a form. It’s a similar process to wet-applied dense-packed cellulose or spray foam.

There must be a surface to spray against, like a hempcrete block layer or plywood.

This is a video of the whole preparation and spraying process. 

Components

Same as in poured hempcrete: hemp hurd, lime binder, water.

How it works

Mixed on-site, like poured hempcrete, but applied by spraying vertically rather than pouring into a form. 

According to Alex Sparrow, who owns UK Hempcrete and is the author of The Hempcrete Book, in the UK it is common to use sprayed hempcrete when renovating old stone houses. The stones have uneven surfaces and spraying allows the hempcrete to fill in the gaps and valleys. 

Spraying in hempcrete: https://www.instagram.com/p/Bz_LQRRBYW7/?utm_source=ig_embed&utm_campaign=loading

Benefits of sprayed-in hempcrete

Same as poured-in hempcrete.

Drawbacks of using sprayed-in hempcrete

Same as poured concrete, plus the possible compression of the hempcrete, resulting in lower insulation values.

4. Hempcrete Prefab Panels

Some companies are beginning to produce prefab wood frame hempcrete panels. These panels combine structural wood framing with hempcrete.

Components

The ingredients in prefab panels are usually the same as hempcrete. But, like blocks, it could vary from company to company, so make sure to find out what the binder is before committing to anything. 

How it works

The panels are framed with wood. They are sometimes referred to as “cassettes”. When using prefab panels, the wood framing is not encapsulated with hempcrete. 

Panels will require more care for air sealing, etc. due to the wood joints. There is also more potential for thermal bridging and condensation. 

Uses for prefab hempcrete panels would be similar to any prefab panel. Wall sections are made off-site and transported to the lot for installation. They could be used in place of hempcrete blocks, with poured or sprayed hempcrete on the opposite site.

A video showing hemp precast panels: https://www.instagram.com/p/Bz8amlcBfr-/?utm_source=ig_embed&utm_campaign=loading

Benefits of using prefab hempcrete panels

  • Possible faster install time.
  • Faster dry time.
  • Less on-site prep.

Drawbacks of using prefab panels

  • More detailing, similar to a traditional construction wall, because wood frame is not encapsulated in hempcrete.
  • More expensive.
  • Less oversight for how the wall is being made.
  • More potential for problems with the wood.
  • It makes interior finishes more tricky (lime plaster over studs?).

Precast panels: https://www.instagram.com/p/ttjdPmhKt4/?utm_source=ig_embed&utm_campaign=loading

5. Hemp Insulation Batts

Hemp insulation is not hempcrete but I thought I would briefly mention it here. It is not mixed with a lime binder that encapsulates the hemp hurd and hardens it.

It is hemp fibers, usually with some synthetic fibers mixed in, made into batts and used in walls just like fiberglass, mineral wool, and other batt insulation types.

My post on insulation mentions this in more detail.

Is Hempcrete Mold Resistant?

Photo courtesy of UK Hempcrete

Plain hemp can grow mold in the right conditions, but hempcrete is a little different.

Hemp–lime mixes can go moldy if it 1) it absorbs water for prolonged periods of time in moist conditions, 2) does not have adequeate ventilation inside or 3) wrong choice of protective coating.

Hemp is made of cellulose (it has even more than wood!) and mold likes cellulose. If you put plain wet hemp in a plastic bag and seal it, it will get moldy. 

Hempcrete has less risk for mold. This is because the hemp in hempcrete is mixed with a lime binder that makes it possible for the hempcrete to harden. 

Lime is what gives hempcrete its mold-resistant property. Lime is alkaline (high pH). Mold, in general, doesn’t like alkaline environments. When the lime binder is mixed in and coats the hemp pieces, it essentially creates an inorganic, alkaline buffer that mold cannot survive in.

However, one study I read found that mold was still able to grow, even in the presence of lime binder, when the hempcrete wall was exposed to heavy rain. 

A lot depends on using the right binder, mixing it correctly, making sure anything put on the walls is vapor-permeable, and avoiding bulk water (rain, roof-run off, etc.)

When a hempcrete house is properly planned and correctly built, the chances of mold growing are likely less with hempcrete than with traditional building materials. 

Do your research on binders before choosing one. There are binders out there that have caused mold problems.

If you want to avoid mold in your future healthy house, proper planning for moisture management (weather and vapor) are essential. 

Please find a qualified architect or building science professional to create a plan for your new healthy home.

What climates are safe for building with hempcrete?

This study found the most microbial growth in a simulated tropical environment. The Mediterranean climate simulation induced the growth of six species of bacteria and four species of fungi, with moderate diversity. In the arid climate simulation only four species of bacteria and two species of fungi appeared. Hempcrete certainly faired the best in the arid desert climate simulation.

There are many hempcrete houses in the rainy UK, as well as institutional buildings and multi-family complexes. In North America, there are hempcrete buildings in coastal North Carolina to snowy Idaho and cold, wet Canada. If you intend to build in a wet climate you should go visit some of these homes when possible.

Since hempcrete is an insulation, it should be just as safe as something like blown-in cellulose. The details will change depending on the climate, however – humid, dry, rainy, cold, warm, etc. 

It might be necessary to protect the exterior wall with large overhanging eaves, or sheathing combined with a rain screen (gap) and siding. 

This is where an experienced architect can help you determine the details that are necessary for your location to avoid mold and rot.

Is Hempcrete Cost Effective?

  • The cost appears to be 10-30% more than typical wood construction.
    • Much of it has to be imported (and it can be difficult to source, depending on where you live).
    • It takes a long time to dry which can slow down the build.
  • The cost depends on the method you use.
    • A double stud wall is more expensive (double cost).
  • There are very few experienced architects or builders.
  • Blocks and precast panels tend to be more expensive because they need to be cast individually unlike a whole wall that can be cast as one.

Related post: on more natural building wall systems to consider.

Where to Learn More About Hempcrete

Helpful books:

Helpful videos:

Trainings:

Products:

Design / Build

USA

Europe

Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

Buy Me a Coffee at ko-fi.com

Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

Non-Toxic Deck Stains (A Comparison)

by Leave a Comment

This article digs into non-toxic and natural options for staining and sealing wood decks as well as most outdoor wood like fences, furniture, windows, doors, play gyms, and planters.

This post covers both water-based sealants and natural oil-based options that are either zero or low-VOC and have been vetted by the chemically sensitive.

Penetrating sealers require that older decks and outdoor wood be sanded all the way down, but the film-forming options can be applied to lightly sanded older wood.

The water-based finishes don’t work over oily dense tropical woods like Ipe, Teak, and Mahogany but the natural oil-based stains and the hybrid work well over these woods.

If you are working with pressure-treated wood, all stains require that the wood has time to dry out first which can take anywhere from 3 months to a year.

If you would like to look at wood types and other decking materials that do not require a finish like composites and even aluminum, see my post on deck materials.

Top picks:

This post contains affiliate links. Upon purchase, I earn a small commission at no extra cost to you.

Non-Toxic Sealants and Stains for Decks, Fences, Outdoor Furniture, Play Sets & Planters

Staining a wooden deck with a all natural tung oil
Milk Paint Company All Natural Outdoor Defense Oil Sealant

1. Vermont Natural Coatings & Böhme – Terra Plus Exterior Deck Stain

Two cans of Bohme Terra Plus

What is it: This is a natural oil / waterborne hybrid penetrating stain. The colors are semi-transparent. It is a waterproofer with UV protection. It has better UV protection than the other options by this company.

Where to use it: On exterior decks and stairs.

Types of wood: Use on new or properly prepared decks. You can use it on Ipe, Mahogany, and Teak as well as non-tropical deck woods (be sure to talk to the company for direction). You only need a light sanding on a previously coated deck because it’s a film-forming sealant.

Specs: Low VOC. One person who was super sensitive thought this was better than PolyWhey. The company describes the smell as a sunflower or pumpkin odor, not a linseed odor.

Where to buy: Through the Vermont Natural Coatings website; sometimes on Amazon.

2. Penetrating Water Proofer Infused With Juniper

A can of VNC Pentrating Water Proofer

What is it: This is a water-based penetrating sealer. It does not form a film and the wood looks totally bare after applying it. The only purpose of this sealant is to provide waterproofing. It does not provide any UV or abrasion resistance. The wood will gray out naturally.

Where to use it: It is used on decks, railings, shake roofs, siding, fencing, indoor/outdoor play gyms, the exterior of planters/raised garden beds, outdoor furniture, and animal hutches/pens. It is not suitable for subterranean or submerged wood. It can be used indoors as well as outdoors. It cannot go over or under another product.

Types of wood: It can be used on new, or weather wood as well as pressure-treated wood. For pressure-treated wood allow 6-12 months before application. It can work on Teak and other oily woods and it is a good choice for cedar, pine, spruce, and fir.

Specs: It is zero-VOC and contains no solvents, dyes, biocides, or fungicides.

Where to buy: From Walmart and you can sometimes find it via Amazon.

3. PolyWhey Exterior Penetrating Wood Stain

Vermont Natural Coatings Exterior Penetrating Wood Stain

What is it: This is one of the most durable water-based non-toxic deck stain/sealers that I know of. This is a semi-transparent stain and topcoat sealer in one. It is a waterproofer with some UV resistance (more UV resistance the darker you go in stain color).

Where to use it: Wood siding, decks, fences, outdoor furniture, log cabins, exterior wood doors, play gyms, swing sets, beehives (it’s well-known for this application), pet hutches, barns, chicken coops, and other outdoor wood surfaces. This coating is great for the exterior of raised garden beds with AFM Dynoseal for waterproofing on the interior.

Types of wood: It can be used on new, pressure-treated, and weathered wood. Like with all deck stains, pressure-treated wood needs to dry out for 6 months to a year before application. Not for use on exotic super dense woods such as Teak, Ipe, or Garapa/Brazilian Ash.

It can be applied over older oil-based stains or finish, as well as other water-based finishes if it’s been fully sanded first so that it can penetrate into the wood. No product can go over top of this in exterior applications.

Specs: It is non-toxic, low odor, low-VOC, and contains no biocides, fungicides, or anti-microbial agents. The pigments act as natural UV inhibitors.

The folks at Green Building Supply have tested the non-toxic options on fences and found this to be as durable as oil-based stains and more conventional toxic stains/sealers.

Where to buy: You can buy it online at Walmart and sometimes via Amazon.

4. AFM Safecoat EXT Exterior Polyureseal

A can of AFM Safecoat EXT

What is it: A clear acrylic urethane coating for exterior use on wood and concrete. This is a water-resistant coating with good abrasion and UV resistance.

Where to use it: On walkways, decks, fences, floors, patios, doors, and pet cages. It can be applied to raw wood or wood stained with AFM Safecoat wood stains, as well as concrete or previously painted (with water-based paint) surfaces.

For abrasion resistance on outdoor tables, a paint and sealer combo would work well: AFM Safecoat All Purpose Exterior Satin and then AFM Safecoat EXT Exterior Polyureseal. (And if you really wanted a painted deck, this would be the only non-toxic combo to achieve that look).

Types of wood: Use on dry and absorbent wood. It can be applied to raw wood or wood stained with Safecoat DuroTone, concrete, and previously painted surfaces that are properly prepared. This product can not be used over oil-based coatings.

Specs: Low-VOC, it also can function to seal in offgassing of hazardous chemicals.

Where to buy: Through Green Design Center/Building for Health.

5. Milk Paint Outdoor Defense Oil

a bottle of Outdoor Defense Oil

What is it: An all-natural oil sealer made from pure tung oil, pine oil, and zinc. Out of the natural penetrating oils, tung oil is the most durable (and also the most difficult to apply).

Where to use it: On outdoor wood like picnic tables, wooden Adirondack chairs, wood furniture, decks, siding, wood fencing, front porches, concrete patios, park benches, wooden storage sheds, wood doors, and windows. You can use it on beehives with a full 30-day cure. This is the all-natural option for sealing raised garden beds (both inside and out).

You can also use this over Milk Paint to protect it from the elements or you can mix (some) pigments into the tung oil.

Types of wood: You can use this on all wood types. Extremely dense woods such as Teak, Ipe, etc may require thinning with more (natural) solvent. Not for use over new oil-based sealers/stains or other finishes. You can use it over aged penetrating oil finishes (like aged linseed oil).

Specs: No metallic driers. Full ingredient disclosure: pure tung oil, pine oil (which acts as a solvent), and zinc. Some highly chemically sensitive folks have preferred these natural oil coatings to synthetic coatings like PolyWhey (others would find the opposite preferable). Always test for your own tolerance and I would recommend not using or being exposed to these natural solvents when they are wet if you are sensitive. My in-depth look at tung and linseed oils goes into more detail.

Where to buy: Through the Real Milk Company’s website. You can use code mychemicalfreehouse for 10% off.

PS to clean your Tung oiled deck, you can use gentle soaps, but some non-toxic cleaners can damage it – this post goes over the best options.

6. Monocoat Hybrid Exterior Wood Protector

Rubio Monocoat Hybrid Wood Protector

What is it: A modified linseed oil and wax penetrating oil finish that is applied with just one coat. It provides protection from water and UV (except for the color “Pure” which has no UV protection).

Where to use it: Wooden decks, façades, patios, shutters, portals, garden furniture, pontoons, windows, doors, etc.

Types of wood: Works well over almost all wood types including oily exotic woods (Ipe, Teak, etc).

Specs: Solvent-free, technically 0-VOC because it’s a natural product. Though see my in-depth review of Rubio Monocoat and other linseed oils for information on naturally occurring VOCs. Rubio Monocoat is preferred to plain linseed oil in many ways because it’s lower in odor. You need a part B accelerator, be sure to test that out as well.

Where to buy: Directly through their website.

PS To clean your linseed oiled deck, make sure to use specialty products that won’t damage the surface.

Conclusion, Top Picks for Deck Stains:

  • Top water-based option: Vermont Natural Coatings PolyWhey Exterior Penetrating Wood Stain

  • Top oil-based option: Outdoor Defense Oil or Rubio Monocoat Hybrid Exterior

    • Bonus: Cleaning and Reviving Your Wood Deck

    Rubio Monocoat Exterior Wood Cleaner

    To remove green algae, moss, dirt stains, and graying from wood prior to staining and sealing your deck or other outdoor wood you can use Rubio Exterior Wood Cleaner.

    Use this before applying water-based stains like Vermont Natural Coatings PolyWhey Exterior Penetrating Stain or oil-based finishes like Monocoat Hybrid Exterior Protector.

    One sensitive person described the feel as a light soap but with almost no odor.

    Related Posts:

    Looking for non-toxic exterior paints? This post goes over the options.

    For a review of deck materials – alternatives to pressure-treated wood, low odor woods, wood that doesn’t need a sealant, and non-wood alternatives, see this post on decking materials.

    How to clean your non-toxic deck? Here are healthy cleaning products for every decking material.

    Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

    Buy Me a Coffee at ko-fi.com

    Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

    Non-Toxic Decking Material Options

    by 11 Comments

    This is a complete guide to non-toxic decking – types, materials, additives, and brands.

    For most people, the main choice is between composite decking and solid wood decking. For the chemically sensitive you will have to get samples yourself of the decking materials as well as the stains needed for real wood – as this choice is very individual.

    The long-term benefits of not having to do any maintenance on composite decking can outweigh the initial concerns.

    There are also some more unusual options to choose from like aluminum decking.

    Composite Decks

    A close up of composite decking

    Material Make Up

    Composite decking material is generally made from a mix of wood fibers and plastic. The plastic is polypropylene (PP) or polyethylene (PE), mixed together with wood dust, pigments, UV inhibitors, and usually borate. This plastic is usually recycled, like from plastic grocery bags.

    If you do well with polyethylene or polypropylene that should be OK for you, but ask to see a sample of the ones available near you and see if you can get a sample of one that is as newly manufactured as the one you would buy. These plastics do have a little bit of odor.

    Most of them now are capped in an outer layer of plastic. The type of plastic is not always specified, but you should ask, especially if you are avoiding PVC vinyl.

    Additional Chemicals During Install

    Glue is not used to install composite decks, but you are meant to seal the rough edges of some brands with a lumber wax – be sure to tests out the product that the company recommends if you are super sensitive.

    Trex does not recommend using a lumber wax, sealant, or any other glue or sealant in the installation.

    The only maintenance needed for most brands is soap and water.

    Mold Prone?

    Many have reported their composite decking becoming prone to growing mold. Some experts have recommended only going with brands that are capped with plastic on all sides to help prevent this issue. Brands with bamboo fibers might also be less prone to mold since the fibers do not clump as much.

    Brands

    Capped composites like Trex Transcend or TimberTech Earthwood Evolutions use a traditional composite decking core with an added plastic polymer cap.

    Trex is the most well-known brand of composite decking made with recycled bags (PE), and it is capped with an unspecified type of plastic, which they said is not PVC.

    Dura-Life brand is a blend of polypropylene (about 20 percent), recycled wood and plastic (about 25 percent), and hardwood flour (about 55 percent). Dura-Life planks have a polypropylene cap outer shell covering the extruded composite core. 

    I have heard from really chemically sensitive folks who did well with Dura-Life. I sampled this one and I would describe the odor as a fairly mild glue odor when sniffed directly.

    A non-wood composite, Lumberock Premium Decking, offers a line of decking materials made from a combination of plastics and mineral materials instead of wood fibers. You might want to check that one out if you are sensitive to the natural odorants of wood.

    Wood-based composites do still retain some wood odor. For example, a cedar composite that I tested definitely smelled like cedar. The ones I tested (Trex, Dura-Life) also have an odor that I would describe as a light glue odor.

    Cost

    A Trex deck typically runs from $9 to $16 per square foot.

    Maintenance

    Non-toxic cleaning products that won’t damage composite decks are here.

    PVC Decking

    A PVC deck

    Material Make Up

    Some PVC decking is 100% plastic and some is a composite decking made of PVC and wood fibers.

    Many chemically sensitive folks like to avoid PVC since it tends to be higher in offgassing, odors, and added chemicals, however, the odor here of the wood-PVC composites is fairly mild and in my experience was milder than the composites above.

    These are some brands that make PVC decking which generally look the same from the atop view as the non-PVC composites.

    Additional Chemicals During Install

    With solid PVC boards you would not need to seal the edges.

    Mold Prone?

    Mold growth would only be superficial on solid PVC boards since it cannot grow in the material. With composite products, if they have real wood in them they likely are prone to mold to some degree, especially if not capped on all sides.

    Brands

    AZEK and TimberTech AZEK products are made from a solid PVC which they claim is highly resistant to stains, scratches, splits, mold, and mildew.

    Despite being PVC, I found that the TimberTech AZEK only had a slight odor when new (when sniffing it up close) – less than the odor of TREX and Dura-LIfe composites, in my opinion.

    TimberTech Pro and TimberTech Edge are composites – a mix of wood fibers and plastic PVC, capped with PVC. (Not capped in PE as some websites say).

    Envision Composite Lumber with no natural wood fibers and PVC. Some lines are capped (in PVC) and some are not.

    EverNew by CertainTeed line includes decking materials that are either solid vinyl or a blend of PVC vinyl and wood flour.

    Fortress Apex PVC Decking’s “foam core” is cellular PVC reinforced with bamboo. The boards are encapsulated in an acrylic polymer.

    Fiberon company makes surface decking, railing components, and fencing products that are made from a solid PVC “Permatek” outer shell bonded to a wood composite core.

    Cost

    Azek is 2-3 times the cost of Trex composite.

    Maintenence

    Non-toxic products that won’t damage vinyl decks are outlined in this post on deck cleaners.

    Real Wood Decks

    Pressure Treated Decks

    Pressure-treated wood for decking is usually pine, treated with copper and quaternary ammonia. The ammonia will offgas from the pine, but for those who are extremely sensitive, they can have challenges with this when it is fresh.

    I have also seen pressure-treated wood treated with flame retardants, though this is not the norm – examples: wood from Hoover and FRX.

    One other challenge with pressure-treated wood is that it can not be sealed or stained for about 6 months when it is new unless it’s already been dried out.

    Cedar Decks

    A cedar deck being installed

    Cedar is the most common natural wood option and it’s good for those avoiding toxins since it doesn’t need pressure-treating (with copper-quats) like pine does.

    Cedar does have a rather strong natural odor which bothers some people with extreme chemical sensitivity. My post on the odorants of wood looks more at this issue.

    Although it doesn’t require pressure treating you should stain it every few years, so you will have to find a sealer you can tolerate. My post on deck sealers goes through the options.

    Usually the base structure of decks is made from pressure-treated wood.

    Redwood is another naturally rot-resistant wood used for decking in North America. Like Cedar, it is not pressure treated and does require a sealant.

    Cedar and Redwood are pricier than pressure-treated pine.

    Ipe Decks

    All natural Ipe wood decking being installed

    Ipe is a wood species for decks that could be ideal for those avoiding toxins.

    Though it’s quite pricey, pricier than Cedar and Redwood, it does not require sealing (or pressure-treating). Though adding a sealer can help preserve it. You can choose between natural oil options and a very low VOC oil/water hybrid detailed here.

    Other Rot-Resistant Woods Used in Decking

    Massaranduba, Cumaru, Tigerwood, Garapa, Mahogany, and Teak are a few other naturally rot-resistant tropical woods that can hold up as outdoor decking.

    Out of the woods used for decking, Cedar is the highest odor wood and Garapa is the lowest. If you find yourself sensitive to the natural odorants of wood, get a few samples of different species and see how you do.

    Samples of low odor rot resistant woods that can be used for decking

    Non-Toxic Modified Woods

    Thermally Modified Wood

    Thermally modified wood for decking is treated with heat. This makes it more durable and gives it protection against rot and termites. No chemicals are used in the treatment. It has the smell of smoked wood.  

    Thermory is a heat-treated wood brand, they say it lasts as long as a tropical hardwood like Ipe.

    There is a wax to seal the edges of Thermory. Other than those edges it comes finished and you don’t have to refinish this again if you don’t want to.

    Acetylated Wood

    Accoya wood is Radiata Pine and Alder species treated with acetic anhydride. The treatment leaves the wood harder, more dimensionally stable, and immune to insects. Some acetic acid is left in the wood and that does leave it smelling a little bit like vinegar.

    You can add a finish or leave it unfinished.

    Furfurylated Wood

    Kebony is another modified wood. Furfuryl alcohol is impregnated into the wood and is polymerized. I’m a little more hesitant to recommend this type of wood due to more unknowns with this chemistry.

    Aluminum Decking

    Aluminum decking
    Photo via www.nexaninc.com

    Aluminum decking by Nexum, pictured above, is made from powdered coated aluminum. A chemically inert product and certainly the safest one on this list for the extremely chemically sensitive.

    The above type is gapless which can help to provide usable area under the deck.

    Related:

    Non-Toxic Deck Stains & Sealers

    Non-Toxic Deck Cleaners

    Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

    Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

    Buy Me a Coffee at ko-fi.com

    Choosing a Non-Toxic Vinyl Plank Floor

    by 86 Comments

    Vinyl Plank, Luxury Vinyl Plank (LVP), and Luxury Vinyl Tile (LVT) are very low in VOCs and offgassing.

    Most people find it odorless, but those like me with a high sense of smell can certainly pick up the offgassing.

    I pick up the chemical odor off every brand I have sampled (they are all very similar) and I do have concerns about plasticizers (which all brands contain) and small amounts of metals, explained further in the article.

    Most of it is phthalate-free now – though phthalates were replaced with alternate plasticizers. The most common plasticizer used now is DOTP.

    Whether vinyl plank should be considered toxic depends on your threshold for toxins in the home and our knowledge is also limited by the current research and understanding of the new plasticizers – which we will discuss.

    There is a huge difference between vinyl plank and sheet vinyl flooring. Sheet vinyl, the very flexible kind that comes in large rolls is way higher in offgassing. It’s one of the top products to avoid in a healthy home in my opinion.

    Vinyl plank comes in two main types: resilient vinyl plank and luxury vinyl plank.

    This post contains affiliate links. Upon purchase, I earn a small commission at no extra cost to you.

    A stack of varies types of vinyl flooring from the thickest multilayer LVP to the thinest vinyl flooring
    The top sample is a vinyl plank (glue down) and the bottom three are luxury vinyl planks which click together

    Vinyl Plank (as Opposed to Luxury Vinyl Plank)

    Vinyl plank or resilient vinyl plank is a much thinner product than a luxury vinyl plank. It’s more flexible than luxury vinyl plank (but not as flexible as vinyl that comes in a roll) and is installed by a glue-down method.

    This type of vinyl has less offgassing of VOCs compared to LVP in my estimation, this is only due to the fact that there is less of it! I would certainly consider this an ultra love VOC product. But you do have to consider the glues used as a source of offgassing (at least until it’s fully cured).

    I have seen some vinyl plank that still has phthalates, so be sure to check to make sure it’s phthalate-free and made of virgin vinyl.

    The ones pictured below are Shaw brand 6 mil Resilient Vinyl plank Flooring. It’s 5/64 inches thick. It’s free of phthalates.

    I have also seen Armstrong “Good” line which is similar.

    You will have to check which glues the brand recommends and will warranty it with but most of them are zero VOC when cured.

    A close up of vinyl plank flooring that is very low in odor
    An example of vinyl plank

    Luxury Vinyl Plank (LVP) (and Luxury Vinyl Tile)

    This type of vinyl plank is thicker, more rigid, has multiple layers, and is click together.

    It has a core (SPC or WPC), a vinyl wear layer, and often has an underlayment attached as well.

    This multilayer rigid core vinyl used to be called EVP – engineered vinyl plank, (though most of the information online is incorrect regarding the definition of EVP). Don’t worry, because this term is almost never used anymore.

    LVP and LVT (luxury vinyl tile) are the same product, the only difference is that LVP looks like wood and LVT looks like tile or stone.

    Let’s look at the chemical composition of the materials.

    SPC Core Vinyl Floors

    Most of the luxury vinyl plank (LVP) click-together flooring has an SPC (stone polymer composite) core. This is a mix of limestone, PVC, and plasticizer.

    It’s low in offgassing due to the high amount of limestone – it’s usually 60-80% limestone and the rest is PVC and plasticizer with no foaming agent. Look out for companies that call this a “limestone core” without mentioning the PVC/vinyl content (it’s still there).

    It also contains some minor stabilizers and pigments (Pharos).

    It is grey in color, very dense and rigid, and looks like the middle layer in these photos:

    A close up of SPC core flooring
    These floors all have a SPC core. The top sample is hybrid (wood wear layer, SPC core), the bottom two have vinyl wear layers and SPC cores

    WPC Core Vinyl Floors

    Only a few brands have WPC (wood plastic composite) – they were originally made with real wood or cork dust but now most of them don’t contain plant-based fibers.

    The WPC core is usually made from PVC, limestone, plasticizers, a foaming agent (like formamide), and wood-like or wood materials such as wood flour. Wood-like plasticizers can be used instead of the wood fiber.

    The primary difference between most WPC and SPC core floors is that WPC contains a lighter extruded or foamed plastic core, while SPC contains a solid denser core with more limestone.

    The Cali Vinyl Plus pictured below has a true WPC core that they call BPC (bamboo plastic composite) which is made with bamboo fibers.

    I generally find SPC to be a little bit lower in odor and offgassing than WPC, but it’s been variable.

    Formamide comes with a Prop 65 label warning.

    WPC is beige or yellow in color, less dense than SPC, and looks like this:

    A close up of what WPC core flooring looks like
    LVP with a WPC core (Cali Vinyl Plus and Montserrat Click Lock)

    Underlayment of LVT

    The underlayment is usually an integrated plastic layer, though some brands, like Coretec, have cork attached.

    The cork adds significant offgassing in my opinion, however, it is going to be almost entirely blocked by the click-together system. (But for those extremely sensitive the offgassing from the cork gets into the other layers during storage, production, transportation).

    I personally avoid the brands with cork underlayment due to the unnecessary addition of VOCs, plus you are adding an organic material that is not mold proof in the way vinyl is.

    The foam underlayments are usually made from IXPE or EVA foam, though some of them smell a lot more like rubber to me.

    Many of the brands have such a thin attached underlayment that you still need to add one, so those don’t add much value. Check the warranty though, as some brands require an additional underlayment and for other brands adding an additional underlayment will void the warranty.

    Brands like Cali Bamboo have a thick and cushiony underlayment (and you don’t have to add another one).

    The underlayment often contains antimicrobials.

    Wear Layer of Vinyl Floors

    I have not found the thickness of the wear layer to affect the offgassing, though it’s possible that there is a minor difference there.

    The wear layer is vinyl without the wood or limestone.

    If you want the floor to last you want to go with the thicker wear layer. Some brands include the black layer (see photos above) that comes right after the top layer as part of the “wear layer”, but that will show as black marks if the top layer wears down! You want to look at the wear layer as the layer that has the integral wood or stone look color and design.

    The top coating is a polyurethane with aluminum oxide cured under UV lights (so there is no offgassing there).

    The wear layer can contain antimicrobials.

    Should you Consider Vinyl as a Safe Flooring Choice?

    These floors can be considered by anyone in the mild to moderately chemically sensitive category.

    Plasticizers are also less of a concern for older folks than those more susceptible to hormone-disrupting chemicals.

    Those who are super sensitive to wood odorants might consider LVP as the next choice after ruling out solid wood, engineered wood, tile, and polished concrete.

    The VOCs are very low but it’s not zero-VOC or odor-free and the plasticizers are for me still an “unknown” factor in terms of safety and health.

    All LVP (and LVT) brands are very similar, there are only four main differences outlined below:

    FOUR Things to Ask (when choosing LVP floors)

    1. Double-check to make sure it’s virgin (not recycled vinyl)
    2. Look for phthalate-free
    3. You might have a preference for SPC over WPC
    4. Check the underlayment, you may choose to avoid cork

    Healthiest (Safer) Brands of Vinyl Plank

    • Virgin vinyl
    • Phthalate-free
    • Made in America
    • Starting at $2.81 /sqft
    • Virgin vinyl
    • Phthalate-free
    • Thatcher and Franklin are SPC core
    • Made in America
    • Dodford $2.75, Thatcher & Franklin $4.59 /sqft
    • Virgin vinyl
    • Phthalate-free
    • SPC core
    • Made in America
    • $5.87 /sqft

    Home Depot Brands

    Out of the Home Depot brands they all have low offgassing as well but are not always good quality in terms of the thickness of the floor and thickness of the wear layer. Traffic Master, Lifeproof (underlayment odor was strong to me), Home Decorators are all very similar.

    All of the Home Depot brands are phthalate-free.

    Phthalate-Free Vinyl Flooring and Replacement Plasticizers 

    Phthalate-free brands are preferable – which most are now. Phthalates are known to be toxic, they have a host of known health problems and they leach quite a bit from floors.

    All brands sold at Home Depot, Lowe’s, and Lumber Liquidators are phthalate-free. Almost all other brands are now too.

    If phthalates (also known as ortho-phthalates) are not used, other plasticizers will be used instead.

    Replacement plasticizers include DOTP (also called DEHT) which is the main one used right now, this is used in the vast majority of brands.

    Based on what we know about DOTP it doesn’t have any known endocrine disruption effects like phthalates do. They also claim that it is more stable in the material and doesn’t leach as much as phthalates. DOTP makes up 8-23% of the product.

    The Ecology Center cites concerns that plasticizers can still leach even if not as much as phthalates and they caution against replacement chemicals like DOTP that are of similar chemical composition. We usually find that in time, with more studies, we find out more about the health impacts. They conclude that we do not yet know the full health effects of this plasticizer and have doubts that it is not in fact an endocrine disrupter.

    I believe that it is currently difficult to say if the current plasticizers like DOTP, and therefore LVP floors as a whole, are non-toxic.

    Other Plasticizers Used

    Some may contain benzoate ester (in the Artistek LVT by Metroflor), I have seen tributyl citrate listed in a past Declare Label.

    Three bio-based plasticizers are used in PVC flooring: Isosorbide diesters produced from fatty acids of vegetable origin and isosorbide derived from glucose (Polysorb ID 37); Acetylated monoglyceride derived from hydrogenated castor oil bio-based plasticizer aka, COMGHA, (Grindsted Soft-n-Safe); Dow’s Ecolibrium plasticizer.

    According to HBN these are well studied and are believed to be the least toxic of the six non-phthalate plasticizers.

    DOTP is not a bio-based plasticizer, despite Cali Bamboo making this claim.

    Toxic Metals in Vinyl Flooring

    Organotins (a form of tin) can be used in the top layer. Antimicrobials can be used, usually in the underlayment. I have seen various types, including silver.

    EHN found the heavy metal cadmium recently in vinyl floors (probably recycled ones, they say).

    It’s important to avoid recycled vinyl.

    Lumber Liquidators and Floor & Decor banned recycled vinyl to avoid the associated toxic contaminants like metals and halogenated flame retardants. Most other brands are virgin vinyl now.

    Lead, cadmium, chromium, and mercury can be present and are only officially limited (not banned), as far as I have seen, by Floor and Decor.

    Though antimony, bromine, and lead have been virtually eliminated according to the latest study.

    Offgassing of VOCs in Vinyl Flooring

    Sheet vinyl is higher offgassing than LVP. Sheet vinyl is in the 0.5 – 5 mg/m3 total VOC range, whereas vinyl click will be less than 0.5 mg/m3. (And it’s actually much less than 0.5mg/m3).

    The offgassing is less of a concern to me than plasticizers (semi-VOCs) which are a longer-lasting and more of a concerning class of chemicals.

    How long does LVP/LVT take to Offgas?

    In absence of studies that indicate when the flooring product is completely offgassed, we have to judge based on our senses. A few months will get the product most of the way there. When I have seen LVP in buildings that are a couple of years old I cannot pick up any offgassing at all.

    Sealing in the VOCs and Semi-VOCs in Vinyl Flooring

    You can seal in any odors as well as most of the plasticizer leaching with shellac. I have tested shellac on various types of vinyl flooring. It has worked well on all the types that I have tried it on from sheet vinyl to a thick rigid LVP.

    The downside is that shellac adds a shiny and less durable (to water) coating on the floor, which takes away from the more realistic wood/stone look and can show damage more easily.

    You can remove the shellac later with alcohol (I used hand sanitizer), but the downside is that if you seal an LVP flooring that is click together it’s difficult or nearly impossible to remove all of the shellac perfectly from within the grooves.

    Formaldehyde-Free LVP Flooring

    No brand of LVP/LVT or vinyl plank adds formaldehyde. Any brand advertising as formaldehyde-free is only stating the obvious which can in some cases be considered an inaccurate insinuation that other brands are adding formaldehyde.

    Greenguard or Floorscore Brands of Vinyl Plank (LVP)

    The VOCs are so low in vinyl plank that they are far below any threshold of the green certifications. No brand is going to be above Greenguard gold levels – therefore whether it’s certified or not does not matter.

    Floorscore to me is a particularly useless certification but definitely doesn’t help differentiate between vinyl plank brands.

    None of the certifications are including the measurement of plasticizers, which is my main concern with vinyl plank flooring.

    Is it Waterproof and Mold Preventative?

    The Locking System

    The thinner LVPs don’t have a very good locking mechanism, it’s more like “set together”. So that isn’t going to hold up well to water. If the product has a really good locking system and it’s installed in a way that it’s not pulling apart or separating then this can be quite waterproof. How waterproof it is also depends on how long the water is sitting on it.

    Contractors recommend starting at 5 mm total thickness for a good locking system.

    The Vapor Barrier

    Another factor to consider is that most brands of luxury vinyl plank and tile require an additional underlayment that is also a vapor barrier under the vinyl. This means that if water gets between the two layers then it cannot dry out.

    Is it Mold Preventative in a Bathroom?

    This is often recommended as a floor for a bathroom and for a basement.

    I have lived in a couple of apartments with vinyl in the bathroom, one was glue down vinyl plank and one had a floating luxury vinyl plank. Both had areas where the seams were not tight and so there is no way I believe this was waterproof. I also wondered about the edges, especially if the baseboard is not caulked to the floor.

    Is it Mold Preventative in a Basement?

    Though LVP is recommended for basement floors because it’s quite resistant to mold I have a different view on the topic.

    Blocking moisture in the slab in my experience is a bad idea. The slab is always trying to dry to the inside as it’s the only way it can dry and it’s often getting wet from the outside/underneath. Any material that blocks moisture can and often does cause mold to grow under the area that is being blocked.

    Cheryl Ciecko, mold preventative architect, has described this situation well. And as an extremely mold-sensitive person myself, I know that this is frequently a problem in slabs. Therefore I only recommend a breathable floor covering on slab foundations and in basements.

    Polished concrete or tiles with a breathable grout are best.

    The Healthiest Alternatives to Vinyl Plank Flooring

    Hybrid flooring which has wood as the top layer and SPC vinyl as the core

    Hybrid Flooring

    Hybrid flooring has an SPC core and a real hardwood wear layer.

    This has less offgassing in my estimation than LVP, it gives you the feel of real wood on top, and I would expect that the real wood would block all or most of the plasticizers from leaching out (it also avoids having plasticizer as the top layer).

    One option is Cali Bamboo Geowood but there are two other brands to check out in the main flooring post.

    Vinyl with a Concrete Based Core

    A concrete based vinyl floor

    Another twist on vinyl floors is X-core Connect by Mats inc. This flooring has a vinyl top layer but the center is a concrete-based material. I have seen samples of this and in terms of health and offgassing, I definitely thought it was an improvement over regular vinyl floors.

    Close up of engineered wood flooring

    Engineered Wood

    Most engineered wood is no-VOC. Look for brands with a plywood or solid slat core. The UV cure polyurethane finishes are also zero-VOC.

    Some brands have an oil-based finish and that is not bad either (ultra-low VOC).

    Avoid brands with an HDF or MDF core. See the post on engineered wood floors to see the different types and brands.

    Polyurethane sheet flooring which is odorless

    Polyurethane Sheet Flooring

    If you want glue-down planks or larger areas of sheet flooring, polyurethane is much safer than vinyl rolls. The brand picture is Wineo. It barely has any offgassing and doesn’t contain plasticizers.

    I talk about it more in the post on RV flooring.

    One plank of click together cork flooring

    Cork Flooring

    Cork flooring is not zero-VOC but it is another option to consider that is very low-VOC.

    My top brand is definitely Amorim Wise as it’s far lower offgassing than any other brand I have seen (most of them are actually high in offgassing).

    They claim it’s waterproof but I personally would not bank on that.

    Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

    Buy Me a Coffee at ko-fi.com

    Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

    Review of Boxabl, Home of Elon Musk

    by 19 Comments

    Review of Boxabl SIPS Prefab House

    The company Boxabl has created a metal SIPs (structurally integrated panel) house that has caught a lot of folks’ attention.

    The main reason it has gone so viral is that it promises it all – fast, easy, cheap, resilient, and healthy.

    My job as a Building Biologist is to review homes for durability, indoor air quality and resilience to mold.

    It may be cheap and fast, but is this home a durable and healthy home?

    First, is it “eco-friendy”

    The basic structure of this house is a steel and styrofoam structural panel. This is very safe even for those with chemical sensitivities. That part has practically no offgassing and I am a big fan of SIPS.

    They also use MgO (magnesium oxide) board on the interior surfaces which is generally safe option as it has extremely low or no offgassing in my experience.

    It’s not clear how that is attached to the walls in this case, it’s likely glued on, which could be a problem for offgassing. (More on in the inherent risks of MgO against steel below).

    The flooring appears to be glue down vinyl, though they have described it in different ways. The countertops and tabletop are laminate (which is a melamine plastic glued onto a substrate which is almost always MDF). And the interior cabinetry is conventional (which is typically particle board and laminate).

    These three elements will contribute to offgassing – VOCs, plasticizers and glue from the vinyl floor; glues and formaldehyde from particle board based cabinets; and glues and formaldehyde from MDF based laminate countertops.

    While this is not high in offgassing per se, according to conventional wisdom, it absolutely could be too high for those who are sensitive to formaldehyde.

    At this time the interior cannot be customized and it includes all the interior finishes other than the bed and sofa.

    Even though it would be quite easy to choose your own healthy floor and cabinets in theory, it would likely be difficult to remove the already glued down vinyl.

    With just a little more effort this company, they could have reduced offgassing significantly by choosing better cabinets, countertops and floors. (Though keep in mind we do not know the exact materials or brands used so I am making some best guesses based on what is most typical right now).

    Is it a durable design?

    In general, metal SIPS are very resistant to mold because as long as the wall remains laminated they are immune to condensation problems. Moisture cannot get into any wall cavity to find a cold spot to condensate.

    If they are well connected and well sealed then they could also be durable against leaks. The waterproofing will depend on how well the seams are connected. I owned a metal SIPS trailer (Camplite) that was very leaky!

    There are a number of concerns I have with this house:

    • There is a clear negative lap at the bottom of the first piece. It’s not just an exterior trim detail, it’s integral to the design. I don’t see how you would not always be battling water pooling up and soaking the wall.
    • It’s nice that it unpacks quickly into a full livable house but how are all those seams waterproofed? I do not think we have enough information on that right now.
    • Because it’s done almost entirely in a factory we would need to see a detailed factory tour to see if this is a good design (the company does not yet have a full-sized factory and is still raising money at the time of writing). There are so many details I would want to see including how the windows and all seams are waterproofed.
    • The house, like all prefabs, needs to be seen in person, especially during installation to see if there are any areas vulnerable to water. Because this company does not have a show house and is not in full production yet, it’s highly unlikely you will be able to see one any time soon. My prefab post goes over the due diligence needed here, and with this house, we don’t have enough information to even do the due diligence.
    • MgO and steel have not gone well together in the past. In Denmark, massive problems (and lawsuits) resulted when salts naturally leached out of MgO board and corroded the metal in the buildings.
    • The website says that Boxabl “doesn’t use lumber or sheetrock” and in an email they said “we do not use wood or materials that can rot or mold”. But in multiple videos, wood appears to be the framing of the edges of the SIPs. Hidden wood in a metal-based house is a problem in my books.

    Is this a reliable company?

    Still in development

    Well, I don’t think we know if this is a reliable company yet. As I discuss in my general prefab post I never go with the prototype of a prefab. They commonly have problems.

    There could be situations in which we know a lot about a company, the construction details, and the testing of the prototype, but I don’t see enough information here to be confident.

    The company needs to raise 10 million dollars to be in full production, and at the time of writing they are still raising money. They are not yet at production stages.

    Inconsistencies

    On the fundraising page it says “early investors get a discount”. When someone asked what the discount is they responded “It is possible there will be a discount. We haven’t announced it yet.”

    In one of the videos, the rep states that you could install this without a foundation or permit. That sounds ill-advised.

    It does not seem like the reps actually know what the floors are made of.

    Elon Musk Involvement

    It definitely adds legitimacy that Elon Musk is living in one. But it’s unclear whether he is backing the company or not. His area of expertise is not in construction but it would be great if he did lend his mind to making this a better built home than what it looks like. It has great potential to solve the problem of lack of affordable and healthy housing around the world. But in my view this house has not proven itself yet.

    Guide to Non-Toxic Glues, Caulks & Adhesives

    by 71 Comments

    Updated Winter 2022

    Testing wood glues, construction adhesives and silicone caulks was the hardest part of building my house since I did this when I was highly sensitive.

    But, you’re going to need glues, caulks, and adhesives if you are building so it’s a good idea to start testing them out!

    You’re going to need them for repairs and renovations too. I would suggest finding out which are non-toxic and which ones work for you before that urgent repair is needed.

    I’m not interested in certifications like GreenGuard Gold here. I’m interested in the official VOC level and how fast it is to offgas. In this type of product, a high initial odor/VOC level could offgas faster than one that is lower VOC, and that can be better for the user. For some adhesive types, the one with the lowest VOC level will be the best. I’ll be sure to specify.

    This post covers low VOC, low odor, non-toxic options that are suitable for chemically sensitive or health-conscious folks.

    [Read more…] about Guide to Non-Toxic Glues, Caulks & Adhesives

    Non-Toxic (Low-VOC) Sealants for Marble, Granite, Limestone

    by 2 Comments

    This is a post is about sealants for light-colored marble, light granites, limestone, and other light-colored cool-tone stones. The sealers are intended for food-contact areas like countertops, stone serving boards, and stone bowels, as well as areas like stone tile backsplashes.

    My post on all-natural oil-based sealers for stones focuses on walnut oil (and other non-toxic oils) that work best on dark-colored, medium-tone (or beige-toned) stones since they do darken and yellow the stones slightly.

    There is no 100% natural sealer for white and light-colored stones. This should be considered early on if it’s a new build for someone chemically sensitive.

    Light-colored stones are also much more likely to be porous compared to some darker-colored stones that can be naturally dense enough to not require a sealant in food prep areas.

    Manufacturers of natural stone countertops usually recommend a penetrating or impregnating sealant every few years (depending on the type of stone, the use, etc).

    These sealants do not fully disclose their ingredients, but I have dug into the literature to see what is likely in them. Most of them use fluoropolymers as the main technology, a type of PFAS. If you are avoiding PFAS, there are two sealants on the market that I list that are low and zero-VOC that are not based on PFAS.

    These four sealers are ones I have researched, compared and actually tested myself. They are the safest, lowest offgassing options out there right now.

    [Read more…] about Non-Toxic (Low-VOC) Sealants for Marble, Granite, Limestone

    Non-Toxic Kitchen Cabinets: Complete List of Types and Brands

    by 56 Comments

    Conventional Cabinets & VOCs

    Conventional cabinets can be a significant source of VOCs in the kitchen – with all of the low and mid-range brands using particleboard or MDF at least in their lower-end lines, which offgas formaldehyde.

    There are pressed wood products with no added formaldehyde now, and some cabinet makers mentioned in this post are using these. I don’t always think the alternative glues are better.

    The move towards CARB II and GreenGuard Gold has greatly improved the formaldehyde levels in the conventional options in recent years.

    Regular plywood-based cabinets (as opposed to particleboard or MDF) offgas quite rapidly, while at the same time more companies are offering formaldehyde-free options.

    Paints and varnishes are not likely to be zero-VOC unless that is stated. But the brands here are offering natural finishes, custom finishes, or factory cured finishes which I found to be almost no VOC.

    You may opt to finish them yourself with non-toxic sealers or non-toxic paint.

    The best option for most people is the mid-range brands with the right healthy upgrades.

    kitchen cabinets

    Healthy Cabinet Brands – Listed by Material 

    Healthy cabinets could be made of solid wood, plywood, pressed wood without added formaldehyde, or metal.

    Sometimes glass or MgO board can be used.

    Of course, some are sensitive to the terpenes of wood, and wood can also pick up and hold onto secondary odors so I have included non-wood options on the list.

    The cabinets in my tiny house are solid wood, but the reason cabinets are made of engineered wood products is that solid wood can warp in the kitchen.

    1. Non-Toxic Metal Cabinet Brands

    White and wood colored metal Kitchen Cabinets rendering.
    Image via FadiorKitchen.com

    There are companies that make metal kitchen cabinets, and they can look quite cool.

    Fadior makes stainless steel cabinets. The cabinets are made of all stainless with aluminum reinforcements, no wood or PVC.

    Bertolini affordable, 100% metal.

    IMD has no wood and no adhesives (North America and Europe).

    Pedini (high-end) Italian company that was at the forefront of green cabinetry. They offer some metal options.

    Contur Cabinets is a Canadian company making metal cabinets.

    Lasertron Direct makes high-end custom stainless steel cabinetry for indoors and outdoors.

    When shopping for metal cabinets you want to see if there are any non-metal components and what those are.

    2. Healthy Solid Wood Cabinets

    Solid wood kitchen cabinets in natural wood color
    Photo via healthycabinetmakers.com

    Healthy Cabinet Makers make solid wood cabinets aimed at the chemically sensitive.

    It’s rare to find cabinets made out of solid wood, so I would certainly go with a company that has expertise with this type of construction. Even the boxes are solid wood.

    Solid wood can be prone to warping in high humidity (if not constructed well by a specialty company like this).

    This company also has a commitment to healthy finishes.

    3. Low-VOC and Formaldehyde-Free Cabinets

    Plywood kitchen cabinets by Kerf in natural walnut and white paint
    Photo via kerfdesign.com

    i. KERF makes modern looking cabinets out of Purebond (formaldehyde-free plywood) which has a zero-VOC finish. The edges are finished with Osmo which I review here.

    ii. Neil Nelly Cabinets makes low-VOC wooden cabinets with no-added-formaldehyde cases/drawers (Purebond Plywood). They use low-VOC glues, adhesives, and finishes. You can ask them about a no-VOC finish option.

    iii. Executive Cabinetry offers a choice between regular plywood and Purebond (no added formaldehyde plywood).

    Classic style kitchen cabinets by Crystal in white and black
    crystalcabinets.com

    iv. Another very popular brand is Crystal Cabinets. They can use standard plywood or Purebond plywood (no added formaldehyde) for the boxes. They have an option for low emitting finishes, or you can finish them yourself.

    You can also have them finish them for you with the varnish of your choice (though that option is fairly expensive).

    Non-toxic cabinets finishes are listed here, and non-toxic cabinet paints here.

    This is often the top pick for many in the high-end green market.

    v. Bellmont Cabinetry offers a line called EcoCore that is melamine over a no added urea-formaldehyde particleboard. Their veneer plywood is a safer choice. They have doors that are solid wood (for stained finish only).

    vi. Taylor Made Cabinets offers custom no added formaldehyde cabinets, with plywood boxes and solid wood drawers and doors. Their MDF is made without formaldehyde.

    vii. Royal Cabinets makes a line called Green Leaf that is made with no added formaldehyde materials (solid wood fronts are an option) and low-VOC finishes.

    viii. Barker Cabinets offers RTA cabinets made with Purebond plywood for the boxes. The raised panel doors (Windsor, Seattle, etc.) are made of solid wood panels (no MDF). The painted doors are made with a conversion varnish that does have some offgassing (the offgassing was low but took about 5 months to hit odorless to me). The stains and clear stains did seem to have some slight offgassing as well (possibly better than the paint, depending on the age of the samples).

    ix. PureKitchen uses Purebond Plywood for the boxes. They made a door style with plywood and solid wood (not MDF). They offer MDF made with MDI glues instead of formaldehyde. The paint is Sherwin Williams Chem Aqua Plus. The glue is a PVA type (which is good).

    x. NorthPoint Cabinets. This RTA line has a solid wood and plywood option. Drawers are made of solid wood + plywood, and the boxes, shelves, and even back panels are made of plywood. The stained doors are solid wood with a veneered plywood center panel. The painted doors are all HDF. The finishes are 100% water-based and UV cured, so there won’t be any offgassing there.

    4. Fully Custom-Made Cabinets

    The simple custom wood cabinets in my tiny house on wheels made of solid wood poplar

    Custom cabinets are usually made by local craftsmen or local companies. This is usually the highest-end option. You can get custom cabinets in just about any style.

    One company I like, Crown Point, uses formaldehyde-free plywood for the boxes and can use solid wood for fronts. They even have experience painting cabinets with all-natural Milk Paint.

    In general custom cabinets can be made with a combination of solid wood, plywood, Purebond (formaldehyde-free plywood), or formaldehyde-free particleboard.

    Purebond plywood is made of “soy glue” which for some people is preferred over regular plywood. Not all chemically sensitive people do well with this.

    Drawers are usually solid wood in high-end cabinets but they can be made of mostly metal (which is what I did).

    In my tiny house, we kept it really simple with basic cabinets made by my carpenter-builder.

    My cabinets, pictured, are custom made with solid wood on the doors/face. MgO was used for the boxes (a highly unusual choice!). IKEA ready-made metal drawers were used with MgO as the base of the drawer.

    The wood did warp a little in my kitchen (this was poplar wood).

    Some ideas to cut down on costs (while keeping the cabinets low in toxicity):

    • Use shelves instead of upper cabinets – either wood, glass, or metal.
    • Salvage cabinets and countertops from demolitions as they may have off-gassed or you may find metal ones.
    • DIY simple open shelving below the counter made of solid wood, concrete, tadelakt, metal, or glass.
    • Metal and glass cabinets you can custom make or make yourself – here is a description and instructions from Build a Healthy House. IKEA also offers some mostly glass options.
    • Incorporate affordable metal drawers or shelves inside of cabinets (like my IKEA parts).
    • Cabinets made entirely of formaldehyde-free plywood (see this video).

    5. Non-Toxic Big Brand Cabinets

    i. KraftMaid Cabinets (Lowes and Home Depot)

    Samples of Kraftmaid solid wood for doors in painted options and clear finish on wood options
    Kraftmaid finishes

    KraftMaid cabinets are a great mid-range semi-custom option.

    They offer all plywood cabinets boxes as an upgrade. The shelves are also plywood. Most plywood now quickly offgasses to completion. It’s a far better choice than particleboard.

    The drawer sides are solid wood, with a plywood base.

    The doors are solid hardwood frames with solid or veneer center panels, or laminate doors.

    I like solid wood as my top choice followed by laminate doors.

    You can order samples for $3 each to see the finishes. I personally found that the painted lacquer finish hit odorless very quickly, within days. I don’t think any instrument would pick up offgassing off these at that time. They said the samples are always newly produced.

    The clear finished seemed even better to me right away. But both finishes would be fine for 99% of folks and both are better than conversion varnish used by other brands.

    KraftMaid cabinets cost you anywhere from $100 to $300 per linear square foot.

    Merillat Cabinets

    Merillat and Kraftmaid are owned by the same company, and Merrillat’s best line, their Masterpiece, is the exact same product as Kraftmaid.

    Other Home Depot Brands

    Many folks have reported doing well with Thomasville brand cabinets from Home Depot.

    iii. IKEA Cabinets

    IKEA is obviously a very affordable ready to assemble (RTA) option.

    From IKEA, the lacquered VEDDINGE cabinets and melamine-faced cabinets are preferred because those finishes block some offgassing.

    The KUNGSBACKA cabinet fronts and side panels are made of PET plastic wrapped around particle board, which is also a great way to block offgassing from the particleboard.

    More on that below.

    Formaldehyde Levels in Big Box Store Cabinets

    Many people are finding that since CARB II came into effect, which drastically reduced formaldehyde in nationwide brands, regular cabinets work fine for them.

    You may want to compare some of the brands at IKEA and Home Depot. If you find GreenGuard Gold certification you know it’s extremely low formaldehyde.

    With most particleboard and MDF, the main adhesive is formaldehyde. You can see the typical levels in the chart in this post.

    I would avoid MDF and particleboard, opting for brands that offer an upgrade to all plywood boxes and solid wood doors.

    My second choice after that is a melamine or laminate finish which blocks most of the formaldehyde.

    Melamine Versus Laquer – Which is Safer?

    IKEA has two main finishes on the doors.

    Melamine is one option. This is a plastic exterior that is fairly thick and does not have noticeable offgassing.

    The other option is the painted (lacquered) finish. This is made with a base of particleboard.

    Lacquer paints do have some ability to seal in offgassing, but this doesn’t block the formaldehyde as well as the melamine or laminate does.

    How to Block & Seal in Formaldehyde

    In cabinets with a melamine or plastic laminate finish on the outside (like many IKEA cabinets) this does block most of the formaldehyde offgassing.

    If the edges are sealed in by the finish, that is even better.

    If the edges are not sealed with melamine, the formaldehyde offgassing from the edges can be sealed with AFM Safeseal or Zinsser Shellac. You should also seal up the unused shelving holes with shellac as well.

    If you go with the lacquered finish you can seal the edges with Safeseal or Shellac.

    Metal and Glass Cabinet Components from IKEA

    The IKEA drawers have metal sides which is a great feature. The fiberboard base can be swapped out for another material.

    IKEA also sells glass cabinet drawers and glass shelves for inside cabinets. The JUTIS line is metal and glass.

    I used their metal drawers and metal corner cabinet shelving in my tiny house and put my own fronts on them.

    You can really cut down on costs and toxin exposure but using many IKEA parts.

    If you want to dig down deeper into materials – my post on Laminate, Melamine, and Thermafoil goes into more detail.

    6. Plastic Kitchen Cabinets

    An outdoor kitchen made of white plastic cabinets
    Photo via werever.com

    Non-toxic outdoor kitchen cabinets can be made of polyethylene or metal. The above cabinets are from Werever Outdoor Cabinets which are made from high-density polyethylene.

    Folks who have not found a suitable material in the indoor options might use the outdoor styles inside. You could, of course, use these outside as intended, as well.

    One benefit here is you might find modular options in this category quickly and easily at big box stores.

    One company, Reform, which makes doors and accessories to fit on the IKEA base cabinet frames, makes a solid polyethylene (HDPE) door line called MATCH. That would be an awesome option for many sensitive folks. You would need to check out the above section on IKEA to see if the base cabinets could suit you.

    Looking for healthy bathroom vanities (that don’t contain formaldehyde)? This post on solid wood vanities reviews the best brands.

    Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

    Buy Me a Coffee at ko-fi.com

    Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

    Guide to Non-Toxic Flooring 2022

    by 337 Comments

    Updated Winter 2021/2022

    The best options are real hardwood, polished concrete, and tile. But specific brands of natural linoleum, carpet, and engineered wood are excellent choices as well.

    There are many choices for non-toxic flooring suitable for the chemically sensitive or the health-conscious homeowner.

    I will look at a few options that are still non-toxic, but not quite as healthy, like luxury vinyl plank, laminate, cork, and bamboo.

    [Read more…] about Guide to Non-Toxic Flooring 2022

    Non-Toxic Insulation: A Complete Guide

    by 160 Comments

    There are so many excellent choices for non-toxic, healthy, green insulation, there should be one to fit everyone’s needs.

    Look out for Greenwashing

    There are many new options that claim to be “green” “soy-based” or are formaldehyde-free – this does not mean that they are VOC-free or safe. Look very closely at what’s in it. Also, flame retardants and mildewcides are not counted as VOCs.

    Green Certified?

    On top of that, certifications are not that useful: almost every insulation now qualifies as GreenGuard Gold, which for sensitive folks is not enough information.

    The post includes the best of green non-toxic insulation and includes a cost comparison as of 2021.

    What is the Safest Insulation?

    Well, that depends. Technically, the options with no offgassing and no additives are the purest. But the natural odors in the organic options might not agree with everyone. Neither will the cost or availability.

    Mineral wool is my top pick for most people, in most cases, because it’s simple in its composition and comes to a complete cure, leaving a zero-VOC product.

    The types are outlined below organized by where they are used in the home, and in the order in which I would consider them.

    I recommend all of the products here, some products have affiliate programs and some do not. Upon purchase, I earn a small commission through affiliate links at no extra cost to you.

    Options Used in Wood Framed Houses

    1. Fiberglass Insulation

    Fiberglass batts in a attic ceiling

    Fiberglass is the most common insulation used in standard stick-framed houses in Canada and the US. For this reason, I am starting here. It’s not actually my top pick in the batts category.

    You can use it between wooden studs of a house, between floor joists, and in the attic. It is used in many trailers, but I don’t recommend that.

    This option has improved dramatically in recent years, and the following brands are now extremely low in VOCs.

    Formaldehyde-Free Fiberglass Brands:

    1. Knauf EcoBatt is recommended by many extremely sensitive folks who could not tolerate polystyrene, cotton, or wool. They are formaldehyde-free and their declare label lists all ingredients down to 100 ppm.

    2. Owens Corning Ecotouch fiberglass insulation has GreenGuard GreenGuard Gold certification. The binder is formaldehyde-free and “made from widely available plant materials”, according to the company. All ingredients except the pink dye are listed. The patent can be found here.

    3. Certainteed Fiberglass insulation is also made with a plant-based binder.

    4. Johns Manville Fiberglass insulation is GreenGuard Gold and uses a formaldehyde-free acrylic binder. A patent by the company that is likely related to this product can be found here.

    What are BioBinders in Fiberglass Insulation?

    We don’t know much about what bio binders actually are, but by looking at this patent you can tell that they look mostly safe. However, it’s hard to zero in on what it is.

    There are some preservatives in there, and when they use a biobased binder it looks like they are adding a biocide. (According to patents the acrylic binders might also use biocides, but which type is unknown).

    Are there Flame Retardants in Fiberglass?

    Fiberglass insulation is made with boron but I don’t see any other flame retardant added, especially in the batts that do not have paper backing, and in the spray in type.

    Neither Declare labels nor the companies’ patents suggest flame retardants. Pharos also does not list flame retardants as a component.

    Blown-In Fiberglass

    Blown-in fiberglass that I have looked at recently contains borates, soda ash, lime, siloxanes/silicates/silane, mineral oil, and an unknown anti-static additive.

    Owens Corning unbonded loose-fill and Knauf Jetstream Ultra look similar. A client reported a “strong smell” from JM Climate Pro Fiberglass blown-in, but I don’t see the ingredients for that one, so I cannot compare it to the other two.

    Fiberglass Insulation Around Pipes

    The fiberglass insulation for around pipes that I have seen is also formaldehdye-free.

    • R-Value
      • 3.5 inches is R-11-R-15.
    • Cost USD (2020)
      • Knaff Ecobatt is 0.49/sq ft and you can buy it at Home Depot or through your contractor.

    2. Mineral Wool Insulation

    mineral wool batt insulation in a wall

    Mineral wool is my top choice for batt insulation. It is in widespread use by builders who build green or high-quality homes and it is the most obvious alternative to fiberglass. It is also easy to source.

    • The batts can be used between wood studs anywhere in the house.
    • It’s very good at staying in place with compression fitting, so it fits well between framing.
    • It fits and holds up well in ceiling joists.
    • It can be used in an attic if detailed really well and if you don’t do well with any of the blown-in options.
    • It can be used on basements walls.

    Non-Toxic Mineral Wool Brands

    1. Rockwool (formerly Roxul) is the most common and accessible mineral wool insulation.

    They have a newer version, called AFB evo, that does not contain formaldehyde. The binder is an undisclosed polymer (a plastic, likely acrylic). It also contains mineral oil. It’s much harder to source than their standard batts.

    The standard Rockwool ComfortBatt does contain phenol-formaldehyde which will cure completely and quite quickly if it’s not already cured by the time it gets to you.

    Rockwool ComfortBatt is the type for perimeter exterior walls, Safe N Sound, their soundproofing version is for interior walls, and ComfortBoard is exterior insulation (outside of the sheathing).

    All three contain the same binders/additives: <3% phenol-formaldehyde, <1% starch, and <0.2% mineral oil source.

    You could try both options (the regular and AFB evo), but there are few situations in which the regular Rockwool does not work for someone after airing it out for a short time.

    2. Thermafiber by Owens Corning is a brand that has a regular phenol-formaldehyde line and a formaldehyde-free line (you will see the letters FF), the latter usually has to be special ordered through a store. They also have a blown-in option as well.

    3. American Rockwool is a brand that is harder to source (in 2020 they stalled production). The company claims no chemical additives or binders, and that would be a bonus for the extremely sensitive. They also have a blown-in option.

    Other Info

    An easy way to cut through mineral wool is with an electric carving knife.

    This insulation has good soundproofing qualities. The Safe N Sound version can be used on interior walls for soundproofing between rooms.

    The fibers can cause a contact allergy if you are not using gloves, but the insulation itself is hypoallergenic for most people.

    • R-Value
      • 3.5 inches is R-15.
    • Cost USD (2020) 
      • $0.95/ sq ft for Rockwool (Comfortbatt, 3.5 inch)
    • Where to Buy
      •  Rockwool and Thermafiber at hardware stores across the US and Canada, or through your contractor.

    3. Wool Batt (and Blow-In) Insulation

    Real wool insulation being placed between studs in a wall
    Havelock Wool Insulation via www.havelockwool.com

    Wool batting might be the next insulation type to consider if you want a non-fiberglass option and you have ruled out mineral wool.

    It can be used between wood-framed walls and in the attic floor. It’s more expensive than fiberglass and mineral wool above.

    Top Brands of Wool Insulation

    1. Havelock Wool has no synthetic fibers and no binders. It’s only wool and boric acid. They provide a Declare Label for all of their ingredients. This is the purest of the wool options (and really the most natural insulation all around).

    It’s definitely a favorite in the environmentally sensitive community. You can buy it online which makes it the most accessible wool brand.

    2. Oregon Shepard adds boric acid, sodium pentaborate dehydrate, and a proprietary component that includes a natural protein, last I checked with them.

    3. Black Mountain NatuWool which is 95% wool and 5% polyester binder and is treated with borax.

    Blown-in Wool Insulation

    The purest option here will be the blow-in wool insulation.

    Some extremely sensitive folks have done well with Oregon Shepard blow-in and another extremely sensitive person did well with Havelock loose-fill. I tested Havelock and found that it did have a noticeable wooly smell, though others have barely noticed it.

    The natural oils of the wool have an odor that may not work for some sensitive people, although it is not an additive or chemical smell.

    While none of them claim organic certification, wool is one of the purest options.

    As for borax/boric acid, I’m mostly concerned about inhalation, ingestion, and absorption through touching eyes and mouth. I’m not very concerned about it once it’s behind the wall.

    • R-Value
      • Wool in batts has R-13.7 in 3.5 inches
        Blow in dense-pack R-value: can be 15.3 in 3.5 inches
    • Cost USD (2020)
      • Havelock Loose Fill is $1.97/sq ft
        Havelock Batts is $1.62/sq ft
    • Where to Buy

    4. Recycled Cotton Batt

    a close up of recycled cotton batt insulation in a wood framed wall

    Ultratouch Insulation is what my builder used in my chemical-free tiny home. If you rule out fiberglass, mineral wool, and real wool, this would be something else to consider.

    It used to be made from new denim scraps, but they have moved to recycled denim now. It does contain boric and ammonium sulfate and an olefin binding fiber (similar to rayon).

    You have to test it for your own sensitivities. I became more sensitive to fabric treatments after I moved into my house (and I had the type made from new scraps).

    I would not use this insulation again due to its poor ability to hold itself tight in the walls, the potential for mold if it gets wet, and the slight odor I picked up.

    It can be used between wood-framed walls though it does not hold itself up well in ceilings/between floor joists, especially compared to mineral wool. I personally would not use it in a basement.

    • Other Info
      • Wear an N95 mask while cutting and installing as it does get extremely dusty when working with it.
    • R-Value 
      • For the 3.5” thickness, you get an R-Value of 13
    • Cost USD (2020) 
      • $0.79/sq ft
    • Where to Buy
      • This had to be special ordered when I built my house. Now, you can buy it at Lowes and Home Depot.

    5. Hemp Insulation

    A person cutting hemp insulation with scissors

    Hemp insulation is the newest alternative insulation in the North American market. It’s been used for much longer in Europe.

    I think it is very promising. It’s harder to source and more expensive than some of the other options in this category, but it could be really great for someone who wants something natural and who hasn’t done well with the other options above.

    Brands

    1. Thermo-Hemp out of Europe was one of the first brands.

    2. NatuHemp Semi-Rigid panels are available in the UK and Canada. Canadian NatuHemp, which can be shipped throughout Canada and the US, is made of 88% hemp fiber and 12% polyester fiber, with no chemical binders and no off-gassing (they claim).

    3. HempWool is 92% wool and 8% polyester. It’s available through their website and ships within the US (not to Canada).

    4. MEM in Canada.

    Companies have been coming and going out of business rapidly in the hemp insulation industry.

    Ask them what they add to it, apart from hemp: alternate fibers, binders, flame retardants, and if it’s organic. And always test a sample first!

    • R-Value
      • It is R-13 for 3.5 inches
    • Cost USD (2020)
      • NatuHemp is $1.80/sq ft
        Sunstrand batt is $1/sq ft
    • Where to Buy
      • Contact the companies on where to source it.

    Blown-In Insulation

    1. Cellulose

    Blown in cellulose insulation in the floor of an attic

    Recycled cellulose is an option often slated for those with chemical sensitivity. It is a blown-in insulation made with recycled newspaper that contains a fire repellent like boric acid.

    Newspapers are made with “soy-based” inks but they still contain many other chemicals in the inks apart from soy, and there are additional additives in the insulation, usually mineral oil.

    Dense-packed cellulose is often used in Passive House design, which has great attention to details around moisture management and green healthy materials.

    It is used in both walls and attics.

    Safe Brands of Cellulose Insulation

    1. Greenfiber brand from Lowes and Home Depot is 85% recycled newspaper. It contains boric acid, sodium poly borate, sodium tetraborate pentahydrate, amylopectin, and mineral oil.

    2. Ecocell makes batts that are a mix of cellulose and cotton. It also contains PET plastic, very small amounts of boric acid, as well as sodium poly borate, and ammonium sulfate. You can find this insulation without ammonium sulfate – that may be special order. This used to be sold at Home Depot but now it’s not clear where to source it.

    3. Weathershield brand by Rona in Canada.

    • R-Value 
      • 13.3 for 3.5 inches
    • Cost USD (2020)
      • $0.32/sq ft

    2. AirKrete Cementitious Insulation

    AirKrete is a cementitious blown-in insulation that claims to be VOC-free. It has passed the “sleep next to it test” of many chemically sensitive people.

    The company, however, has declined to participate in the industry-standard VOC test as well as the proper R-value test, so there is some doubt around this product’s claims.

    We don’t know what the undisclosed 2% of this product’s ingredients are, but many with severe chemical sensitivities have chosen to go with this option and have done well with it.

    Because it is a foam, it will get into all the cracks and crevices and therefore give you a higher “real life” R-Value than the batts.

    Some people have reported shrinking, crumbling, and trouble drying. Here is the source for the concerns.

    Paula Baker-Laport continues to recommend this insulation, so I’m assuming that many are still doing well with it.

    It can be used in walls and roofs. (Consult with an architect when designing an unvented roof).

    Non-organic options like AirKrete are more likely to be hypoallergenic.

    • R-Value
      • R-13 for 3.5 inches
    • Cost USD
      • Around $2.25/sq ft including installation costs
    • Where to Source
      • You would have to check to see if you have a certified installer in your area before proceeding.

    3. Real Wool, Mineral Wool, and Fiberglass Blown-In

    A close up of blown in fiberglass insulation in a attic floor with a man measuring the depth of it

    These three insulation types can be blown in as well. Fiberglass (pictured) is the most common blown-in insulation, followed by cellulose.

    Mineral wool and real wool blown-in are less common but are healthier choices.

    Brand names can be found in those respective sections above.

    Exterior Insulation for Houses 

    1. Styrofoam/Rigid Foam

    i. Polyisocyanurate “Polyiso” Foam Board Insulation

    A man installing thick polyiso insulation between wood studs

    Polyiso is one of the insulation types that is used on the exterior side of sheathing.

    Typical current blowing agents for polyiso are CO2 and pentane. There is some “thermal drift”, meaning the blowing agents offgas over time. The offgassing is extremely minimal.

    This is going to become a very common exterior insulation as building codes move towards requiring exterior insulation.

    It can be used in trailers and metal structures as well. It’s not to be used under slabs.

    Flame retardants are a bigger concern than trace pentane. The most common flame retardant is TCPP. It’s best to look for brands that don’t use a halogenated flame retardant like TCPP. Newer and safer flame retardants are non-halogenated phosphorus-based.

    Though the foil does block the FR, the edges are unsealed and it will never be perfect.

    Healthy Brands of Polyiso Foam Insulation

    1. Johns Manville Foil Faced Polyiso has been the most popular brand among those who are sensitive, but they have discontinued Energy 3E, which was the one made without TCPP (all they have said is that it is phosphorus-based and is non-halogenated).

    2. GAF polyiso EnergyGuard-NH uses a halogen-free flame retardant (which is phosphorus-based, like the Energy 3E FR was). “Unlike TCPP, the flame retardant becomes part of the polymer backbone of the insulation—so there is no free flame retardant that can leach out”, according to GAF’s director of sustainability Martin Grohman. “TCPP, by contrast, is not chemically bonded to the polyiso polymer, so it can more readily escape.” Source

    3. ZIP System R-Sheathing is the Huber Zip OSB sheathing, polyiso, and weather-resistant barrier all in one. Though you can use the above two brands as exterior insulation on the outside of the plywood or OSB, “ZIP-R”, as this type is normally called, is integrated with the sheathing, with the polyiso on the interior side.

    • R-Value 
      • Technically it’s R-6/ inch but it’s really about R-5.6/inch over its lifespan because it loses R-Value over time. It also loses R-value the colder it gets.
    • Cost by R-Value (R6)
      • R-6 is $0.60 / sq ft

    ii. Extruded Polystyrene (XPS)

    A close up of pink XPS foam board insulation on concrete

    XPS (extruded polystyrene) is another common exterior insulation outbound of the sheathing. It is also used on exterior concrete basement walls, underneath the slab, and in trailers.

    XPS, like polyiso, has some “thermal drift” i.e. some very slow offgassing of the blowing agents over time.

    “Over a long period of time (50 to 75 years), the blowing agent slowly diffuses through the thickness of the foam” (source).

    Typical blowing agents for XPS are CFC-12, HCFC-142b, and HFC-134a, but they change their formulas over time.

    HFCs contribute to global warming. Changes started January 1st, 2021. Eleven states have banned foams blown with HFC-134a and other high-GWP blowing agents, including HFC-245fa as of January 1st 2022. A ban on high-GWP blowing agents also went into effect in Canada on Jan. 1, 2021. Canada did not ban HFC-134a but created maximum GWP for foam blowing agents.

    XPS insulation was treated with the flame retardant hexabromocyclododecane (HBCD) until recently. The two main brands, Dow Styrofoam (Lowes) and Owens Corning Foamular (Home Depot) no longer contain HBCD.

    Most are now using a butadiene styrene brominated copolymer as the flame retardant (Source). DOW lists a brominated flame retardant (FR122P) in some of their XPS.

    How Concerning are These Flame Retardants in Rigid Foam?

    Flame retardants are sometimes considered non-volatile and sometimes semi-volatile. They leach out in dust form as opposed to gas. If they become dust borne in the house, the main route of exposure is hand to mouth, though you can also inhale them.

    My post on Flame Retardants goes into more detail.

    • R-Value
      • R-5/inch
    • Cost by R-Value
      • R-5 is 0.60/ sq ft

    2. Mineral Wool Board 

    A man placing a board of mineral insulation on the exterior of OSB sheathing

    The other common and easy-to-source exterior insulation used in the US and Canada is Rockwool, in board form.

    The Rockwool Comfortboards will be used more and more as many codes across the US shift to requiring exterior insulation.

    Foam and Rockwool will be the two main exterior insulation types to consider since they will be familiar to builders and easy to source.

    The boards can also be used on interior basement walls. They are also being used under the slab, as the only alternative to foam insulation there.

    • R-Value 
      • R-4/inch
    • Cost by R-Value (R6)
      • R-6 is $1. 24 sq ft

    3. Cork

    The exterior corner of a building that is covered completely in cork insulation

    Thermacork insulation, unlike cork flooring, does not contain adhesives. It is held together by compressing it with heat which releases a natural binder in the cork.

    The cork does give off a smoky smell that dissipates with time, as well as the natural odor of cork.

    This is a newer product in North America and is more expensive than the more conventional options.

    If you can afford it, it is my top pick for non-toxic exterior insulation due to a lack of additives and flame retardants.

    It can be used as exterior insulation or even the facade of a house which serves the purpose of siding, insulation, and noise reduction.

    See this post as an example or cork used as the facade.

    • R-Value
      • R-4/inch
    • Cost by R-Value (R8)
      • R-8 (doesn’t come in R-6) it’s $4.93/sq ft for the insulation type (rougher than the facade)
        R-8 in the facade grade, which covers your exterior insulation and your siding in one, is 10.77/sq ft
    • Where to Buy
      • You can buy this through green building supply stores.

    4. Wood Fiberboard Insulation

    Wood fiber insulation boards stacked up side by side

    Wood fiberboard is often used in High Performance/Passive House designs as exterior insulation. It can be used closer to the interior as well.

    One popular brand in North America is Gutex. It is 95% wood (spruce/fir, post-industrial, recycled and new wood), 4% polyurethane, and about 1% paraffin. The total VOC level is 187 μg/m3.

    • R-Value
      • R-3.7/inch
    • Cost
      • R 5.8 is $1.81/sq ft
    • Where to Source
      • You can buy this through 475.

    Insulation Typically Used in Trailers, RVs, and Vans

    1. Rigid Foam

    EPS (Expanded Polystyrene aka Styrofoam)

    EPS insulation being installed on the exterior of a commercial building by a guy being held up by a harness

    EPS (expanded polystyrene) is often used in trailers and can be referred to as “block foam” by the companies.

    It can also be used as exterior insulation, insulation over concrete basement walls on the interior, and under the slab. Though you are far more likely to see the XPS type of styrofoam under a slab.

    Blowing Agents

    EPS usually is made with pentane as a blowing agent, the final product has trace amounts of pentane which dissipates rather quickly and completely. Some butane can also be used as a blowing agent.

    Sometimes the only blowing agent is carbon dioxide (based on DOW xnergy Declare label).

    Zero-VOC

    EPS, despite the name (polystyrene), does not offgas styrene under normal conditions.

    It is considered 0-VOC (and pentane and styrene are not exempt from the VOC testing).

    What about Styrene?

    The concerns over polystyrene (styrofoam) and styrene comes from the following a) chemicals released during the manufacturing of the product b) the product is very toxic if you burn it and c) the styrene can leach if you drink beverages especially hot or acidic beverages out of styrofoam cups.

    This is a very old product with a long track record. Here are a couple of links to back up the claims.

    In the form of insulation, I would consider this product to be non-toxic, zero-VOC, odorless, and stable, with the only risk being the flame retardants.

    Flame Retardants

    EPS used to be treated with hexabromocyclododecane (HBCD), but luckily it no longer is. Polymeric FR (a copolymer of polystyrene and brominated polybutadiene) is now the most common FR.

    The foil faces on these insulations block the flame retardants. However, the foil and plastic-backed versions can have some offgassing odor. Some EPS is not backed with anything.

    EPS used in packaging and cups does not contain a flame retardant and people have sometimes been able to source this type of foam for small structures.

    If using EPS in a living space I would recommend borate treated foam to prevent ants from tunneling in.

    R-14 for 3.4 inches EPS.

    2. Reflectix and Prodex Insulation

    A roll of reflextix insulation

    Reflectix is a bubble foil made of aluminum over polyethylene bubble wrap. It is flexible, very thin, and claims to have a very high R-value. The thicker version claims R-21 (which is higher than 5 inches of wool).

    These claims are disputed by Green Building Advisor and the Government of Canada. The former states that the 3/8th-inch foil has an R-value of only 1 (the same as a single pane of glass).

    This would hardly be useful anywhere unless it is in a curved trailer, RV, or vehicle where all other options have been ruled out. Sometimes it’s just used to insulate windows, which can be a great help.

    Prodex is another similar material – foil and polyethylene-based – that also has a disputed R-value.

    Many similar brands can be found easily on Amazon or Home Depot.

    3. Aerogel Insulation

    A small sheet of aerogel insulation

    Aerogel is a fairly new product – unusual, extremely expensive, and harder to source.

    The term itself can refer to a variety of materials from the original silica translucent product to polymer-based products that may include the addition of fibers.

    The original Aerogel insulation was developed by NASA.

    Aspen Aerogel collaborated with NASA to make their polymer enhanced aerogel combined with fibers.

    Some companies are selling insulation online that they claim is Aerogel. I would look closely at what’s really in it. Look for proper studies on the R-Value of it.

    They claim an extremely high R-value of R-10 to R-30 per inch.

    This may be ideal for small, round, and difficult to insulate places, if you can source it.

    4. Thinsulate Insulation

    A small folded sheet of thinsulate insulation

    3M Thinsulate (SM600) is an insulation used in vans, other vehicles, and RVs.

    It is made of polyethylene terephthalate (a type of polyester) and polypropylene fibers which will be tolerable for most people. The backing is polypropylene.

    One percent or less of the additives are proprietary and therefore unlisted. The health rating is 0 which is good.

    What I don’t love about using this product in vehicles is that the insulation itself is vapor permeable and it is attached to the walls with 3M 90 Spray (GreenGuard certified, not GreenGuard Gold, not reported to be very tolerable by many chemically sensitive people).

    You may find this insulation tolerable and it may be a good product for a tiny house or structure.

    You can buy it on Amazon and Ebay.

    R-value

    5.2 for the 1.65 inch

    NB. I have seen similar but more unusual insulation made from polyethylene and polyester for homes in batts. (It is more popular in some countries outside of North America.) It may be tolerable depending on what is added to it.

    5. Vacuum Insulation Panels 

    Vacuum Insulation Panels have the highest insulation value of any of the insulation materials.

    These Panasonic panels have an R-Value of R-60 per inch. They were used in the latest Leaf House design (tiny house). This could allow you to build a tiny house for almost any climate. Though this introduces a tricky metallic vapor barrier which needs to be carefully thought out.

    The foil vacuum pack will block any VOCs from migrating through, but your moisture management system would have to be planned carefully here.

    These won’t work in most houses. You might consider them in some trailers or metal framed homes.

    They are very pricey and harder to source than almost all of the other options.

    6. Non-Toxic Spray Foam Insulation

    A person in full PPE spraying in 2 part polyurethane insulation

    Spray foam that is used to fill cavities of walls is two-part polyurethane. Some of it may have soy added, but it’s still mostly polyurethane foam.

    This insulation has to be mixed perfectly, under the right conditions (there are many), and applied correctly. When looking for a good spray foam you are looking for an excellent installer (the best one you can find) and not a specific brand.

    The companies have claimed that it is no-VOC, or close to that once cured, but many individual tests and many individual noses of those sensitive have shown otherwise.

    I know moderately sensitive folks who have looked at many houses with spray foam and been able to pick up the odor for two years.

    And that’s when it’s done right. When it’s done wrong it’s a massive disaster that can end in a lawsuit against the company, plus an expensive imperfect removal of all the foam.

    If you are extremely sensitive you would lose the whole house if this goes wrong, as the VOCs will soak up into other materials. This has happened to two of my clients.

    Brands:

    Icynene and Demilic are both 2-part polyurethane spray foam.

    Whether they have soy or castor oils in them is insignificant in my overall view.

    Icynene OC No Mix is still a 2-part polyurethane foam and although it appears to mix in the gun, the installation still has to meet all of the other parameters.

    One part polyurethane:

    One part polyurethane, which is the canned stuff discussed below, is much easier to tolerate, it’s used in small quantities, and it doesn’t have the same challenges and risks as the 2-part foam.

    Insulating Around Windows and Doors – Non-Toxic Options

    eight bottles of great stuff 1 part polyurethane insulation

    Spray foam is often used around windows and doors. HandiFoam is GreenGuard Gold and will be tolerable for many folks after curing. In Canada, the best source is Organic Lifestyle.

    I find this spray foam to be odorless once cured.

    Other brands like Great Stuff, which you can find anywhere, seem very similar to me, if not the same.

    Great Stuff does contain a flame retardant in some of its lines and Handi-Foam has declined to answer whether it contains a flame retardant or not.

    a roll of polyethylene backer rod

    Instead of using spray foam around windows and doors you can fill in the gaps with Backer Rod and seal with non-toxic caulk if needed.

    I have a post on caulking if you need to test multiple brands.

    a banner advertising posters for sale. it says "20 printable posters for a healthy jobsite, buy here" it shows examples of 4 posters. click anywhere on the banner to go to the store to buy it.

    Corinne Segura is a Building Biologist Practitioner with 7 years of experience helping others create healthy homes.

    Did you find this post helpful? If so you can buy me a coffee to support the research behind this blog. Thank you!

    Buy Me a Coffee at ko-fi.com