My Chemical-Free House

A Guide to Creating a Healthy Home

Healthy Building

Study of Lead in Tile (12.5% Contain Lead)

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I conducted a study of lead in tile in 2021. I chose 64 tiles from major retailers in the US and had them professionally tested with a handheld XRF down to 0.00 mg/cm2.

The 64 porcelain and ceramic tiles came from 14 brands and 5 major retailers in the US. Many of the tiles will be available in Canada as well.

The tiles were purchased from Flooring Inc, Stone Tile Depot, Build Direct, The Tile Shop, and Home Depot.

While there are no official limits on the limits of lead in tile in the US, I used a couple of benchmarks.

The first is the level of lead in paint that qualifies it as lead-containing paint. That is 1.0 mg/cm2; 3% of the tiles came in well above this level.

The next benchmark I used is 0.1 mg/cm2 (I actually used 0.09 since one tile came in that close to 0.1). This level of lead in mg/cm2 could still indicate a level of 500 (or more) parts per million (ppm) of lead.

How did I choose this level that I consider to be above trace? Soil contains 50-400 ppm lead naturally (so that can be considered to be trace, source here)

12.5 % of the tiles contained 0.09 mg/cm2 or more lead in the glaze.

Why Should We Care about Lead in Tiles?

While lead in tiles is not considered a risk when the tiles are in place (in almost all circumstances), the dust produced when cutting or demolishing the tiles could easily produce a lead risk.

Just as we are concerned about chipping and flaking paint, in my opinion, we should be just as careful with a product that is installed and demolished in a way that produces a lot of dust.

Contractors are rarely careful with this dust.

It is reasonable to choose to take lead remediation level precautions with all tile dust, however, that is impractical in the real world that contractors and homeowners live in. And also, why are we accepting the tiles that will have lead in the glaze when it’s not necessary?

How Does this Compare to Previous Results?

The amount of lead used in tile glaze has certainly been going down over time.

Heavy metal content in US ceramic floor and tile dropped by 93.6% between 2002 and 2012 (Healthy Building Network).

In 2010, the Ecology Center tested 39 ceramic tiles for sale at Home Depot and Lowes. They found that 74 percent of the tiles contained detectable lead, with levels as high as 1,900 parts per million. (However, “detectable” here could mean anything above 0 ppm). (The Ecology Center)

You can find the whole study here.

Is Plywood Toxic? (Non-Toxic Alternatives)

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This post provides an overview of the formaldehyde and formaldehyde-free glues used in plywood.

I look at the offgassing levels and rates of formaldehyde in various types of plywood so that you can choose the lowest VOC option and minimize offgassing in the home.

There are non-toxic plywoods as well as non-toxic alternatives to plywood listed here.

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

What is Plywood?

Plywood is an engineered wood product made up of thin layers of wood called “plies” glued together. Each layer is laid with the grain running in the opposite direction to the previous layer.

Where is Plywood Used in a House?

  • Often used as sheathing on the exterior of the wood framing of a house
  • Often used as roof decking
  • Often used as subflooring
  • Often used as the boxes of cabinets, and as structure inside sofas and other furniture
  • Sometimes used as an underlayment or the structure of countertops
  • Sometimes (rarely) used as interior walls
A stack of plywood of different thicknesses

Myths About Plywood

That it offgasses forever

Plywood made with phenol-formaldehyde rapidly reaches no-detectible levels. Plywood made with urea-formaldehyde offgasses for longer, but it is up to 60% of the way there in 30 days. Plywood made from urea-formaldehyde is generally avoidable.

That it is high in formaldehyde

Plywood made with phenol-formaldehyde is not high in formaldehyde since it rapidly reaches non-detectable levels. Interior furniture grade plywood (which can be made with urea-formaldehyde) needs to come in at 0.05 parts per million formaldehyde.

That it is toxic

Plywood made from phenol-formaldehyde is not toxic. Plywood made from urea-formaldehyde is also technically not considered toxic at 0.05 parts per million formaldehyde. But those with compromised detox systems can find this level to be toxic to them. Whether it’s toxic or not very much depends on how much plywood is in the room, the size of the room, airflow in the room, and the person that is being exposed to it.

Which Chemicals Offgas from Plywood

Overview of the Adhesives Used in Plywood

Phenol-Formaldehyde (PH) (aka phenolic glue) – Most of the plywood I see now is made with phenol-formaldehyde. The offgassing is much lower and in many products comes to a complete cure in a short amount of time.

Urea-Formaldehyde (UF) – This is the type of formaldehyde that offgasses at higher levels and for longer. When you think of furniture or flooring that is offgassing for many years it was likely made of urea-formaldehyde. The offgassing rate of UF plywood varies by the exact formula (also some companies use heat to accelerate the offgassing) – it can vary from 15-60% offgassed in 30 days (source). Remember offgassing is on an exponential curve.

Melamine-Urea Formaldehyde (MUF) – This is a urea-formaldehyde glue modified with melamine and PVA. It gives the plywood more water resistance and is usually only used for exterior door skin, marine plywood, and concrete formwork plywood. Adding melamine reduces the formaldehyde offgassing levels (source).

No added Urea Formaldehyde (NAUF), this almost always means PF is used.

No Added Formaldehyde (NAF), this means that no formaldehyde is added to the product – the glue used does not contain formaldehyde. They cannot be labeled “formaldehyde-free” because wood naturally contains formaldehyde. No added formaldehyde plywood is made with “soy-based” glue.

Soy-Based Glue – Soy-based glue is not just one formulation. They use soy protein mixed with polyamidoamine-epichlorohydrin (PAE), isocyanates, and aldehydes. (From the co-inventor of the adhesive for Purebond Plywood). This one is called soy-PAE. A similar type of soy-based glue that may be used to replace formaldehyde in MDF and particleboard is an amine-epichlorohydrin adduct/soy protein/isocyanate (source).

a close up of the veneer on a plywood sheet

Types of Plywood and Their Glues

Structural Plywood

Structural plywood is softwood plywood (SWPW) and it is used for roof sheathing, subfloor, and roof decking.

This type of plywood is made with phenol-formaldehyde as the binder/glue (3.5% formaldehyde to be exact). Phenol formaldehyde is the least toxic type as it offgases less than urea-formaldehyde and it off-gases faster.

Formaldehyde Levels

Formaldehyde levels in freshly produced plywood start out below 0.1 parts per million (ppm). But “emissions rapidly approached zero as the panels aged. In fact, the levels were so low and so close to the ‘background’ levels in the test chamber that it was not possible to measure them accurately” according to the American Plywood Association.

While the APA would not say exactly when the PF levels approached zero (or close to it), I do think that a few weeks is more than adequate for most people.

For most people, exterior plywood in a build will be sufficiently offgassed by the time the building is complete.

Testing Your Reactions

If you are extremely sensitive you should test out plywood when new, after a few weeks, and after 2-3 months of airing. You should also compare that to OSB, to see which is better for your health (I certainly prefer plywood to OSB). The extremely sensitive can often pick up the residual odor of the plywood glue even after the point where it’s undetectable by any instrument. It also becomes difficult to tell where the formaldehyde from the glues ends and the natural level of formaldehyde in the wood starts if you are sensitized to it.

Marine-Grade Plywood Glues

In the US, the marine-grade plywood I’ve seen is made with phenol-formaldehyde, but it can also be made with melamine-urea formaldehyde.

This is not a specific type of plywood in Canada.

Pressure-Treated Plywood Additives

Pressure-treated plywood is commonly treated with alkaline copper quaternary (i.e. copper and quaternary ammonia) (ACQ).

Copper Azole (CBA) is another type, which contains copper, tebuconazole, and possibly boric acid.

Though some wood is still treated with chromated copper arsenate (CCA), this is rare nowadays and it’s definitely not often used in residential buildings.

Product Certification Levels for Formaldehyde

A chalkboard looking graphic that says formaldehyde CH20

CARB II – Formaldehyde Levels CARB II is a standard set by California for products sold there, but when it comes to common building materials like plywood, all major manufactures tend to comply with California’s standards.

Products that fall under this standard include hardwood plywood, medium-density fiberboard, and particleboard – these are pressed wood products sold for interior use.

It does not regulate exterior sheathing products like structural plywood (softwood plywood) and OSB.

(The allowable limits for TSCA Title VI are the same as CARB).

CARB II Formaldehyde Limits Are: Hardwood Plywood 0.05 ppm (parts per million)

The CARB II limit is the same as the GreenGuard limit.

Furniture Grade Plywood

Interior grades of plywood can be made with urea-formaldehyde as the adhesive. Urea-formaldehyde (UF) offgasses more and for longer. Now phenol-formaldehyde (PF) is more standard, but I still see some SDS sheets showing urea-formaldehyde.

Interior plywood is often called furniture grade or hardwood plywood. You will want to make sure your furniture is made with PF or NAF glues, not UF.

Formaldehyde-Free Plywood

1. Purebond Plywood by Columbia Forest Products is a no added formaldehyde plywood (NAF). It is made with a soy-based glue.

When folks talk about formaldehyde-free plywood, this is the one they are usually referring to.

Their adhesive is partially proprietary, but they claim it is “soy-based”. The full Declare label is here but this doesn’t tell us much about what it will offgas in the end, only what went into it.

I have seen extremely chemically sensitive folks react to this brand of plywood so I would make sure to test it out yourself before using it. I do think the odor is extremely mild and unoffensive.

Purebond plywood is intended for interior uses like furniture and cabinets (here are some cabinet makers who use Purebond). It is not structural and it is not made to hold up to high humidity or moisture. Some folks are using this as sheathing and roof decking which is a very bad idea.

You can buy it at Home Depot.

2. SoyStrong Hardwood Plywood is another brand of formaldehyde-free plywood made with a soy-based glue.

You can buy it at Lowes.

How to Offgas Plywood & Seal in the Formaldehyde

1. Give it Time to Air Out

Stack your plywood in a garage or covered area in a way that allows each piece to have some airflow.

Time, heat, and air are the main ways to allow any material to offgas.

2. Seal it

Whether you should seal your plywood partially depends on where it will be going.

If it’s on the interior of your home, then no problem, seal away.

Exterior applications, like wall sheathing and roof decking, are trickier. Wood naturally has the ability to absorb and release moisture. Stopping that natural process could cause problems.

To seal plywood there are a few ways you could go, but the two main options are AFM Safeseal which is a clear acrylic-based coating that helps to block and seal in formaldehyde, or shellac which is an alcohol-based natural wax coating. Shellac does a slightly better job at sealing.

someone brushing on a milky-clear sealant on plywood to seal in the formaldehyde

Alternatives to Plywood, Which Are Less Toxic?

1. Formaldehyde-free plywood is a good non-toxic alternative to regular plywood in most interior applications and in furniture.

2. OSB is often used in place of plywood in structural applications. I don’t consider OSB to be less toxic, as it has higher offgassing and takes longer to come to completion but it’s possible that it works better for some people since the glues are different.

3. XPS foam can replace plywood as wall sheathing (but it’s probably not a good idea in most situations).

4. MgO board can sometimes be used as the subfloor and other sheathings (and I even used it for cabinet boxes and countertop underlayment).

5. Solid wood can replace plywood in some applications, like purlins or skip sheathing on a roof, in subflooring and sheathing, and for cabinet boxes and most furniture.

6. Georgia-Pacific DensGlass can replace plywood sheathing in some areas.

7. Cement board is sometimes used as sheathing, especially in tropical areas. Another concrete-based board, USG Structural Panel, is a thick and very strong board, it is sometimes used on foundation walls when the framing is metal.

8. Drywall, drywall is generally zero-VOC so it is technically less toxic than plywood but there are not many instances where they are interchangeable. If plywood is an option for your walls then you may prefer to use drywall.

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

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Sources

https://pharosproject.net/common-products/2078999#contents-panel

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723320/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723320/

Hempcrete for Mold-Safe, Healthy Homes

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Hemp can be used in building homes in many ways. 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.

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.
  • Industrial hemp is grown with large amounts of fertilizers.
  • If not planned, mixed, and detailed correctly, it can become moldy .
  • The lime dust can be hazardous – one of the hydraulic set lime binders includes a “may cause cancer” warning.
  • 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?

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

Photo courtesy of UK Hempcrete

 

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 where there shouldn’t have been any. 

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?

It seems that hempcrete can be used in almost any climate, with the right details and correct installation. 

There are many hempcrete houses in the rainy UK, as well as institutional buildings and multi-family complexes. 

In North American, there are hempcrete buildings in coastal North Carolina to snowy Idaho and cold, wet Canada. 

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.

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Smoothing the Seams in Mobile Home Walls (With Non-Toxic Materials)

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Walls in mobile homes have a vinyl layer on the wallboard and battens covering the seam gaps. It is possible to remove the battens and mud over the seams. It is also a good idea to prime the walls with BIN Shellac primer to stop any offgassing or leaching of plasticizers from the vinyl.

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

That Kilted Guy recommends the following:

  • Remove the strip
  • Sink the existing nails
  • If there is movement in the boards use screws to secure it, that will prevent cracking of the mud
  • Use drywall mesh tape on the seams
  • Use USG Easy Sand 45 or Easy Sand 20 which are zero-VOC drywall muds.
  • Add texture to even out the surface (since the vinyl is not smooth like the mud)

Corners:

Another contractor recommends using paintable caulk at the small seams like in the corners. Regular paintable caulk is an acrylic latex, and in my opinion, this is too high in offgassing.

A healthier option is a polyether caulk there like AFM Caulking Compound. If you don’t do well with polyether caulking you can use a 100% silicone (like the non-toxic brands outlined here) but then you need a shellac primer before you can paint the caulk with regular paint.

Painting:

One contractor recommends painting the vinyl walls first with a Zinsser primer. BIN Shellac is a great block of VOCs or other chemicals that could be leaching from the vinyl. Those who are chemically sensitive do find that BIN Shellac needs some time to offgas itself but it’s usually well worth it to wait for that to offgas so that you can achieve that blocking of what is below.

Texture:

Orange peel texture often works the best over these types of walls. USG Sheetrock Spray Texture is a good one that is zero-VOC. There is more info in my post on drywall texture and drywall mud.

You can watch a video tutorial here:

Non-Toxic Paint Strippers (All Types Compared)

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First, a History of “Wack A Mole” on Toxic Solvent-Based Strippers

Pre-1970s benzene was a popular paint stripper, it was later determined to be carcinogenic. It was replaced by methylene chloride, a very fast and effective paint remover. Methylene chloride/dichloromethane (DCM) is now considered a neurotoxin and a possible carcinogen that has caused many fatalities. It is banned in the US and many countries.

The latest replacement NMP (n-methyl-2-pyrrolidone), which is not as harsh as Methylene chloride, and is actually quite tolerable for many chemically sensitive folks, does have a Prop 65 warning for birth defects or other reproductive harm. I list only one paint remover with this chemical alongside many alternatives.

In the mainstream realm, new formulas are being sold with acetone, turpentine, toluene, and xylene. I don’t list any paint strippers with these solvents because their higher VOC levels emit the strongest fumes and they are challenging to use.

An Alternative, Safer Solvents?

There are better options now, lower (and even zero-VOC) formulas. Safer more environmentally friendly solvents include dibasic ester, bio-based solvents, and alcohol solvents.

In this article, I look at those options along with “soy-based” and “citrus-based” paint and varnish strippers – though these terms are misleading because they don’t refer to the active majority ingredient. Often the majority ingredient is NMP, but I list brands with safer solvents.

You still need to wear protective gear including safety glasses, gloves, and a mask. Though all of the options here can technically be used indoors.

These safer solvents do work but they take considerably longer on most coatings than the harsh solvents of the past.

Solvent-Free Options to Remove Paint

Depending on what kind of paint or varnish you are removing and what the substrate is, there may be other (solvent-free) options. In this post I discuss – boiling with baking soda, mechanical options, and eco-friendly lye-based options.

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Non-Toxic Deck Cleaners (For Every Deck Type)

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This post covers deck and outdoor furniture cleaners that are safe for you, your kids, your pets, and your plants.

Some are simple DIY natural recipes and others are ready to use soaps that are eco-friendly (and biodegradable). These are healthier alternatives to bleach and toxic deck cleaning formulas.

I list which options are appropriate for wood decks, painted decks, composite decks, and vinyl decks.

The same solutions that work on wooden decks also work on fences, siding, and outdoor furniture.

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Non-Toxic Deck Stains (A Comparison)

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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.

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.

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

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:

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.

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Non-Toxic Decking Material Options

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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.

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Choosing a Non-Toxic Vinyl Plank Floor

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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
  • Virgin vinyl
  • Phthalate-free, unclear which plasticizer they use sine they have given contradictory statements
  • SPC core
  • $2.69 /sqft for Builders Choice; $3.79 /sqft for Vinyl Pro; $3.99 /sqft for Mutestep; $4.99 /sqft for Longboard

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 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 once (source).

Companies like Cali Bamboo have claimed in an email that they use bio-based plasticizers, which should mean it’s either Grindsted Soft-n-Safe (made by Danisco/DuPont) or Polysorb ID 37 (made by Roquette).

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

Cali Bamboo reps also sometimes claim they use DOTP, so it’s not at all clear what they use.

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.

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Review of Boxabl, Home of Elon Musk

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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.