mold prevention

Non-Toxic & Natural Alternative Building Systems

November 8, 2019 by Corinne 3 Comments

The following are concrete and natural earth-based wall build systems that do not offgas toxins and are suitable for the chemically sensitive.

These are alternative build types, the options for building a healthy home apart from the standard timber frame, fiberglass, and gypsum boards.

Drywall now has its own dedicated post here: Guide to Non-Toxic Drywall Types and Brands.

This post contains affiliate links to relevant books and products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you.

Pumicecrete Walls

Photo via buildahealthyhouse.com/2017/05/17/pumice-crete

A mix of pumice and concrete is poured into forms to create these non-toxic walls. They can be made load bearing with a concrete beam. Test pumice for radioactivity and for odors that it may have picked up prior to installation.

Check out Margaret’s blog where she outlines the build of her healthy pumicecrete house.

HempCrete

An interesting material making a comeback, HempCrete is made of hemp and a lime-based binder. Hempcrete is either used to replace insulation in the walls or as the final wall itself.

They are not load-bearing so they are made with a wood frame.

HempCrete claims to not mold, but a natural fiber in a breathable wall is not something I would consider mold proof.

See my detailed post on HempCrete for much more info.

Consult with an architect to make sure this is right for your climate.

Wood Insulated Concrete Forms

Forms are made of a mix of remineralized wood and concrete. Inside, rebar is used as reinforcement and then they are filled with concrete.

Insulative fibers can be added or they can be filled with part concrete and part clay or non-toxic insulation. Brands include Nexcem (Durisol) and Faswall.

Faswall is currently the only brand available in the US (2017). Nexum is available is based in Canada and they sell and ship across North America as well as to Australia and other Pacific Rim countries.

Aerated Autoclaved Concrete (AAC)

Tiles of autoclaved aerated concrete by Sealle **CC BY-SA 3.0**

Concrete-based blocks made from quartz, lime or cement, and aluminum powder. Test thin-set mortar for sensitivity. Hebel is one brand in the US. It’s not approved in California (2017).

Insulated Concrete Form ICF

Nudura blocks (US and Canada) and Fox Block (US and Canada) are the most popular brands right now. ICF could mean different types of foam with concrete fill, but typically it is EPS. See my post on Insulation for a detailed review of EPS. Nadura has a dye. Both have flame retardants.

Is Concrete Non-Toxic?

Portland Cement is non-toxic. It should be confirmed that it is free of admixtures such as air entrainment and water-reducing agents, accelerants and retardants, and superplasticizers.

Ceramic Cement (Magnesium Cement) is also generally a non-toxic option.

Which Concrete Aggregates are Chemical-Free?

Natural non-toxic mineral aggregates should be used. Toxic aggregates include crushed brick, crushed sandstone, concrete slag, fly ash, cinder, and volcanic materials other than pumice. (Source: Prescriptions for a Healthy House).

Earthern Walls – Cob, Adobe, Light Stray Clay, Straw Bale, and Rammed Earth

These are all different types of walls made of clay, straw, and sand.

Houses made of all-natural materials feel great to be in and there is no need to worry about any offgassing.

However, there are precautions that should be taken to avoid mold. These types of buildings might be best suited to dry climates so that there is no chance of mold forming. Some people seem to be doing very well in adobe houses in the south-western US.

If straw is used in the walls it should be carefully sourced to be free of mold and pesticides. When building with cob, adobe or light clay straw there needs to be a dependable dry season of three months for the walls to dry out properly.

They are particularly suited to be heated with wood stoves as that dries out the walls well in the rainy and damp seasons (source: Econest).

An above-grade stem wall and proper drainage around the house are also very important to keep the walls from getting damp.

I’m hearing some bad stories of mold forming on cob and straw bale homes in cold climates, this is likely due to high humidity inside in the winter. I do not feel confident enough in this building system to recommend it for climates where it is not a native building practice.

“WISE – auditorium” *by hattheant is licensed under* CC BY-ND 2.0

Another natural wall system worth mentioning in a little more detail, Rammed Earth, uses sand, gravel and clay and has had an interesting development recently. Foam has been added for insulation and steel for support, and 5-10% cement is added to the clay mixture. It’s called Stabilized Insulated Rammed Earth.

Water does not penetrate the walls, however concrete, especially when not climate controlled is extremely prone to mustiness.

Corinne Segura is a Building Biologist Practitioner with 8 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!

Building for the Chemically Sensitive

September 15, 2019 by Corinne 6 Comments

Those who are building and have moderate to severe chemical sensitivities have a number of factors they need to consider in the very early stages of the planning of the build. You could easily end up between a rock and a hard place without considering these details in advance. I have seen it many times!

It’s incredibly important to build in a mold-preventative manner in order to recover in the new house, and it can at times be difficult to balance those two needs together. So the following areas to consider also apply to those building for mold prevention.

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

Here are areas that must be considered in the very early stages of planning a house if you are chemically sensitive:

LOCATION – BEFORE YOU DRAW UP THE HOUSE

1. Climate

Before you draw up plans for your house, you need to know the location primarily because you need to know the climate zone. This will impact your design significantly.

This can impact your foundation type (and many who are building mold preventative want to use a specific type of foundation), it will also impact insulation requirements – with many areas in the US starting to require exterior insulation, you need to know if you can tolerate Rockwool Comfortboard, rigid sheathing or cork, for example.

It will impact many other materials choices as well as HVAC system requirements.

If you are deciding between two cities or towns we can still start to put your materials list together and see if that impacts the type of house you can build in each area.

2. Topography

The exact piece of land can impact the design as well, since you will look at the topography of the area and site itself, and how that will impact the design – this could influence the size and shape of the house for example, as well as how the crawl or basement is designed, where you will place the garage etc.

This is also important to factor into your budget. If you have a slope or are creating a hill for the house drainage it will impact costs as well as the lot size (distance you need from other houses/property lines).

Though you could work the other way around, pick land that is flat enough and large enough to fit your design.

3. Building Codes

Another reason you will want to know the location, including possibly the exact location, is because building codes and neighbourhood requirements will impact which materials you can use.

These could be codes around things as major as the minimum size of the building, and as small as the type of plumbing you use, for example. Those with MCS are often on a budget and want to build small, and you will almost certainly have materials that you have to rule out due to sensitivities.

4. Neighbourhood or HOA Requirements

Neighbourhood requirements can impact facets of the build like the type of siding that is required. In some historical areas wood siding is required, sometimes even a specific type of wood. Wood siding is not the most durable option for rot prevention, and those with MCS may need to avoid certain types of wood (like cedar).

There are areas where roof types are dictated by the local requirements, this could rule out a metal roof (which is what most with MCS want to use). There are areas that require flat roofs (though you can make it look flat usually and meet that requirement). Those are just a few examples.

EARLY STAGE DECISIONS- AFTER LOCATION BEFORE DESIGN

1. Wood Framed House?

At this point in the process, you will need to have an idea of what materials you tolerate. The more info you have on which materials you tolerate the better.

Most who are sensitive to wood are not sensitive to wood when it’s in the walls – but you need to know which category you are in. You need to know if you are designing a wood-framed house or something entirely different!

If you are avoiding wood altogether you may want to consider other climate-appropriate options which could be metal and foam, metal SIPS, adobe, hempcrete, concrete, and insulated forms.

I discuss alternative walls systems in this post. The post on tiny homes talks about some other unusual systems.

My post on (regular sized) prefabs covers more alternative systems.

Choosing the materials that are tolerable and healthy for you is one of the main things we will cover in a one on one consult.

2. Plywood and OSB?

While many with MCS want to avoid plywood and OSB, avoiding those two items will create a lot of “work around”. Most sensitive folks do use plywood though not all.

You may be able to use alternative sheathing, or you may have problems with code, you may have a much more expensive house, or you may in the end have to go with a totally different type of house than a wood-framed one.

I encourage those with MCS to read through this post on plywood and OSB before ruling it out.

I help folks go through these areas of the build that they have to consider, test options, and weigh the pros and cons of the alternatives.

There are ways to offgas and even seal plywood which could in the end save a lot of money and worry. Or you might want to build with an alternative wall system.

3. Insulation?

You should also have an idea of which insulation you can tolerate. This is another main area that comes up in every consult.

Your typical build has rigid foam in the slab, breathable insulation batts in the walls and depending on the design and climate, spray foam in the attic.

If you need to avoid spray foam insulation (which in general I would), you need to make sure your design takes that into consideration.

With batting, go through the options in the insulation post, as those are the ones we will go over in a consult. If you cannot tolerate any of the insulation batts, again, this will dramatically change the type of house you build.

DURING THE DESIGN PHASE

Decisions that impact the design

1. Avoiding Spray Foam

If you don’t tolerate spay foam insulation make sure to design a roof and foundation that do not require it.

2. Avoiding Laminated/Engineered Lumber

If you want to avoid laminated/engineered lumber to avoid extra glues (see this article to see what I mean), this has to be considered very early in the design. You can only span so far with traditional lumber, so this will change the whole design of the house.

3. Avoiding Ductwork

If you want to avoid all ducted HVAC due to extreme mold sensitivity, this has to be factored into when designing a house.

If you want to avoid AC altogether due to sensitivities, that part definitely has to be factored into even earlier into the location. Even if you don’t mind hot temperatures, you have to look at summer humidity since AC brings down humidity.

4. Design Areas to Consider

Consider simple roof designs to cut back on where things can go wrong, consider large overhangs to protect the walls, simple floor plans can help with cost reduction, carefully design plumbing in an interior wall that has access panels.

5. Avoiding Toxic Windows

You need to design the house around the windows! Yes this is that important of a factor. Many super chemically sensitive folks have run up against this problem too late in the build.

First, the very sensitive will want to go with aluminum windows (see my post on windows), and those can only be found in certain standard sizes (unless you go for totally custom, very expensive windows).

Aluminum windows are already expensive. If you don’t design around those sizes you are going to end up with either windows that you don’t tolerate potentially (fiberglass, vinyl), reframing the house (big expense), or custom windows (another big expense).

AFTER DESIGN BUT BEFORE BUILDING

1. Testing Materials

In order to not delay the build you want to make sure you have tested out all the materials needed down to the caulking, glues, sealants, grouts, thinset, and all the major materials as well.

What can happen here is that if you need to make a substitution, some items are special order and need to be considered early on.

You don’t want to delay the project with special orders and you also don’t want to delay the project because you need more time to test out materials.

If you are extremely sensitive you will either be factoring time in for the house to offgas before you move in, or possibly building a type of wall system that limits the types of glues, caulks, tapes that you are reactive to (alternative wall systems are listed here).

There are certain corners that cannot be cut while trying to eliminate offgassing. I’ve seen it done a lot in houses built for the extremely chemically sensitive. But long-term, you cannot cut corners on the integrity of your building system which is designed to keep out water, moisture, and air. Preventing mold is very important for those with MCS. Cheryl’s course on building a mold preventative home is essential.

You want a builder who understands when materials can be substituted out and when they can’t. Some builders will do whatever you want done because they don’t have a high degree of understanding of building science, and so they don’t know why that will fail.

Or, on the other hand, they may be too rigid and reluctant to change anything, again because of lack of knowledge of how to keep the integrity of the system while doing something slightly different.

I will work alongside your architect and builder to make sure that the right compromises are made.

2. Contracts

Make sure the builder understands your level of chemical sensitivity and how important this is. You need to have certain requirements here in your contract to protect your site and your build. Paula Baker Laport outlines this in her book Prescriptions for a Healthy House and Cheryl also covers key areas of the contracts in her course Building a Healthy Home.

You also want to work with your architect to produce a contract that will help protect you on the mold-preventative building front.

CHOOSING AN ARCHITECT AND BUILDER

1. Your Architect

An architect is needed in any build to help design the moisture management systems.

An HVAC specialist will likely be needed if you are doing a ducted system (or any other complex system).

When looking for an architect, you need someone whose specialty is mold prevention and/or high-performance systems like Passive House.

Anyone who has a high commitment to design and details that prevent moisture problems, rot, decay, and mold is what you are looking for. This can be worded as fine craftsmanship, high performance, increased durability and similar terms which are geared at the non-sensitive.

These builders do higher-quality work, their houses cost more and they have to market this to the general public as high performance or durability.

This video goes over the conflict between finding a builder who builds high quality mold preventative houses and one who will build for MCS. Many get scared away by clients with MCS as it costs them money and time and so it’s important to have your materials list well thought out before contacting them.

2. Your Builder

The same thing goes with a builder. A builder should be highly skilled, highly detail oriented, a perfectionist with getting the details right, someone who understands building science and has an interest in it. A good problem solver, can think outside of the box to accommodate you, while also understanding any repercussion of going too far against the norm.

The builder should have total buy in to the idea of building to accommodate your sensitivities and be thoughtful and mindful so that the wrong products are not brought in accidentally, in a hurry or to clean something up.

You builder should also be highly cooperative with your architect and with you (or your supervisor).

Highly skilled builders will be interested in building a well planned and very well executed house and will not have a problem with working with your architect and you to get it done right.

If they are not used to building high quality work, this will be a battlefield.

You can find a good builder through a good architect or you can find one on your own who you like. When I see high quality builders I list them here (though I don’t know all of them well, and they are only as good as the weakest labourer or as good as their supervision).

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.

Healthy Home Building Consultant

September 9, 2019 by Corinne 11 Comments

I have been helping folks create healthy homes for over 8 years now!

A certified Building Biologist Practioner, I began this journey with the build of my own tiny chemically safe house, the place in which I started to recover from mold illness and severe chemical sensitivity.

My main expertise lies in materials available in the US and Canada.

Healthy home consults are for you if:

You own or rent a house, apartment or trailer
You are building or remodeling
You live with environmental sensitivities, allergies or asthma, including the most severe levels of MCS
You are the homeowner or renter

Areas I assist you with:

Healthy Material Selection

We will go over your specific sensitivities, needs, and level of toxin avoidance, and you will come away with a list of products to use in your build or renovation.

This may involve self-testing materials for your own reactions. If you don’t have reactions (or obvious reactions), I will use your level of toxin avoidance to recommend products.

You will come away with pros and cons of materials you might have read about.

I will take into consideration the system as a whole, so that your moisture management system is intact and point out areas that are mold prone.

If it’s a new build, you will come away knowing the typical steps to choose an architect, builder, materials and job site supervisor.

I help sensitive folks who range from those with mild allergies to those with extreme chemical sensitivities.

I’m not just analyzing the SDS and what the manufacturer is telling us about what’s in it, I’m also using industry knowledge to suggest what additives are typically used and undisclosed. And I use my experience and that of thousands of chemically sensitive folks to choose the safest products.

Note: Topics I Don’t Cover

Remediation and testing of mold, pesticides, lead, radon and asbestos (consult with specialists in those fields).
Pest control choices (consult with a non-toxic pest control specialist).
Mechanical systems: HVAC, appliances, electrical system concerns, and water heaters (consult with experts in the required mechanical field).
Building science advice (should be provided by an architect, engineer, or other building science expert).
How long does x take to offgas. Unless it’s a simple chemical that has been studied, it’s not likely someone has the answer to this. I have sniff tested many products myself and have experience from thousands of chemically sensitive folks, but I don’t have an answer for every product.
EMFs/EMR
Materials outside of North America – Evaluation of building materials, homes, and products outside of Canada and the US.
Recommend a builder – I don’t recommend specific builders including tiny house companies. I do have some builders, designers, and architects on my resource page and can guide you through the process of finding a builder. More on why I don’t recommend builders here.

Tiny Homes & Shelters for the Mold & Chemically Sensitive

September 4, 2019 by Corinne 33 Comments

Related posts:
1. Regular-sized non-toxic prefab homes
2. Mobile homes on wheels for those with sensitivities
3. Emergency shelters for those with sensitivities

Simple, Small Modular and Custom Homes for those Sensitive to Mold and Chemicals

These are small and tiny houses (not on wheels) that are suitable for those with extreme sensitivities to mold and or chemicals.

Not all materials will work for all folks, that is why this article features everything from all wood, to all plastic and all metal homes.

I have natural materials on the list as well, like hemp and concrete.

These small houses are ideal to create a healing space away from conventional housing that is so prone to problems.

This post contains an affiliate link to a home sold on Amazon. This home was on this list before they starting selling through Amazon. Upon purchase, through affiliate links I earn a commission at no extra cost to you. This post is not otherwise sponsored by any of the companies.

1. Passive Home Tiny Homes

https://unityhomes.com/our-designs/nano/

Besonwood is a high-quality passive home custom prefab company. Their custom Thoreau Cabin home is 150 sq ft. The owner chose the stone facade but that is not a typical facade. They are custom homes so they can build any size.

Their predesigned wing is called Unity Homes. Their smallest house “Nano” (pictured) is 477 sq ft.

They are wood framed with passive house design, made to high standards. This would not work for those extremely sensitive to offgassing as their walls include OSB and engineered wood framing.

The insulation used is Rockwool and cellulose in the model I saw (they have different wall systems to choose from).

This is a house that mold sensitive folks should consider due to their high-quality design, high-quality factory-built, and indoor factory conditions. This is at the top of my list for a reason, I would build with this company.

You still have to have planning and supervision on the site prep, foundation and the installation of the prefab components. Every detail matters for mold prevention.

2. All Wood Prefab

Photo Here: https://www.instagram.com/p/B0WFlacAU-2/

The Holz100 homes come in all sizes from very very tiny, small and large.

The walls, floor and ceiling are all wood, no glue, no nails. The roof will not be all wood, there will need to be another roofing material there.

I have a more in depth review in the general prefab post.

I think this house is very promising but needs more investigation. If you tolerate wood there is nothing else in the interior.

To hit codes you will need to put exterior insulation on it. Exterior foam insulation would also be a fool safe method to prevent possible condensation within the air pockets of the wood wall. That is how I would detail it for mold prevention. This would make it quite pricey.

3. Wooden Treehouse

From Out N’ About, a company that rents out treehouses, sells plans and parts, this 16′ Treezebo Hexagon could be a great non-toxic home.

The plans for the treehouse includes a 3-hour consultation.

I like this simple option if you don’t need insulation. Using a rot-resistant wood and no need to worry about the foundation type simplifies everything here.

This can be a mold preventative option.

4. Arched Cabins

The basic kit for Arched Cabins includes floor plates, ribs, ridge beam, standard R13 insulation, Super Span Roof Paneling, trim, and fasteners needed to assemble the cabin.

Arched Cabin kits do not include the foundation, installation, interior, end caps, delivery.

What I like about arched cabins is that there could never be any leaks with this one-piece roof/siding.

In this design, you can use spray foam insulation (with or without rigid foam) without worrying about exterior leaks getting in behind. Spray foam, while it does offgas, is a vapor barrier and the best bet for insulating metal walls in heating climates. It’s risky though to use anything with an exterior vapor barrier (no rain screen) in a heating climate. Spray foam could pull away from the skin. Plus spray foam off gasses too much for chemically sensitive folks.

Either closed cell (2 part) spray foam is used to form an airtight vapor barrier in any climate where you heat, or not quite as foolproof is rigid insulation installed with canned (1 part) spray foam).

This could work for preventing mold, but I don’t think anything with a metal exterior is a good idea in heating climates, it’s far too dependent on spray foam holding up perfectly or a plastic barrier holding up perfectly. I would not risk that myself. And I would not use anything with an exterior metal or fibreglass vapor barrier in a heating climate myself.

The large overhangs are also superb protection from rain over the windows and doors on the ends.

The 12×12 kit is $2400. This is a simple, mostly metal kit that you could then customize to be chemical-free on the inside.

You can see a video tour here and you can check one out on Airbnb.

5. Plastic Domes

These cool Intershelter domes are easy to transport and assemble and have a lifespan of 30 years.

The larger domes are made of a fiberglass composite material that the company says does not emit an odor. Some sensitive people say fiberglass needs some time to offgas (1-2 years or more) and others find it OK fairly soon after production.

The small domes are 14 feet and are made of ABS plastic, which is a really safe plastic (the same plastic the LEGO is made of). This one they say has an integrated foam component.

I would look closely at the details on the panels that have integrated foam. You would want to make sure this is not likely to leak.

If this is done well this would be much easier than trying to put foam insulation on the inside of the one-panel fiberglass domes yourself.

The integrated foam would be ideal for heating climates (cold climates).

Installing foam in the larger domes with an exterior vapor barrier is not simple in heating climate. If you are in a tropical climate this might be ideal.

6. Plastic “Lego” Home

EverBlock makes plastic blocks that fit together like lego. You can make a simple structure out of these.

It’s a safer plastic than fiberglass that is much more tolerable for the chemically sensitive.

7. Plastic Module Homes

There are a few designs that are using metal framing with a plastic body. I find this design extremely promising.

The Coodo above is made in Germany and can deliver all around the world.

A similar company, AluHause is American, with a show house in Palm Desert.

The downside is that fiberglass does offgas and won’t work for many sensitive folks, at least not right away.

Both have the potential to be very waterproof and mold-resistant designs. Neither one gives too much away on how it’s built exactly, so we cannot evaluate it in great detail.

Just like when looking at larger prefabs you have to go through the reconnaissance process outlined here.

Another similar model is the Haus.me which I go into more detail on in the prefab article. This one looks to be a different type of plastic, not fiberglass, though they don’t say which type. They claim that it doesn’t offgas.

Photos here: https://www.instagram.com/p/B1916GAIsFr/

8. Simple Wooden Cabins

Solid wood very basic wood cabin

Leisure Cabins bare bone wooden cabins are made of solid wood. I see some OSB in the subfloor but that could be avoided. Opt for solid wood for the roofing as well.

There is no insulation so they would be difficult to live in in extreme temperatures.

It does not include roofing shingles and roof prepping, stains, railing, foundation, and deck or windows. You do your own wiring, plumbing, and systems as well.

This version is a thin wood wall, not very warm. And when you start to insulate something like this you start to get into a complicated design (I would not recommend insulating anything that does not have a rain screen).

In that case, I would prefer to go back to a prefab like the Unity Homes on this list which already has a well-thought-out wall system, or even design a house from scratch.

Trying to make one of these kits work with insulation is working backward from a plan that won’t likely come together in a mold preventative way in climates where heating is used.

They are produced in Canada.

Amish Built Wood House

From Backyard Buildings in Maine, these tiny houses are a good deal. They are custom built. This one pictured is from a member of the EI groups on Facebook and I have her permission to post about it.

The house is made of local wood, non-fiberglass insulation, low VOC adhesives, a woodstove (but you could use electric heat), wired for on-grid (but can do off-grid as well), cedar siding, metal roof, and plumbing.

This does become a complicated system to design when you add insulation.

When I tried to work with this company, it was difficult to communicate with the builders (because of lack of technology/being Amish). They were mixing some traditional building with some more modern techniques like adding exterior foam insulation and in my opinion it is not mold-safe or detailed right.

They can be moved though they are not on wheels.

When buying a shell you also want to make sure it has a vented rainscreen if you are going to insulate it, otherwise you won’t be able to build that out properly.

It’s not likely that the rainscreen, WRB, and window flashing in done right in these Amish shells or full builds that I have seen. I would not personally go with or recommend this option.

A Traditional Log Cabin

https://www.montanamobilecabins.com/projects-updates

For a thicker wood wall look at a company like Montana Mobile Cabins. This true round log cabin does not use insulation.

I much prefer this simple design than to try and insulate a wood-framed cabin. This is a much safer bet for mold prevention.

It’s not perfect as I have heard of condensation in log cabins, I would consult with a building science expert on how to make this work in your climate.

Prefab Square Log Cabins

Photo here: https://www.instagram.com/p/BJi5A7SgtDQ/

I like the thick square logs too. I like that they would fit together well. In theory, this might create a more airtight assembly which might help prevent moisture and condensation issues.

Confederation Log Homes above makes custom prefab log homes with square-cut logs. The company has been around for a long time.

This is the first log home company I would look at due to their extensive experience.

9. A Metal SIPS House

The Nomad Cube

The Nomad Cube is a promising little metal SIPs house. It can be built out to be very non-toxic.

Metal SIPs make up the main walls and roof of the house and are made from laminated steel-EPS white styrofoam-steel. They are essentially 0-VOC and extremely resistant to mold as long as the panels stay laminated together and assuming there are no leaks into the panels.

The smaller Nomad Micro has been redesigned since I originally wrote this. That one is no longer a SIPS house. Also be sure to ask about and eliminate wood in the structure.

The Nomad Cube is 13 x 13.

You need to add: shipping (From Vancouver BC), platform/slab/or piers, installation, wiring, heat, plumbing, hot water heater, roofing membrane, interior walls, baseboards, shower door, ladder/stairs, fridge, range, and hood vent.

My most sensitive friend tested the SIPs and thought they were good. It is possible to complete the interior with non-toxic materials.

The basic design of this house is metal framing with metal SIPs. It appears in one of their videos that there is plywood in the base, which I would change.

You will need to have a building science expert review this design and help with the details along the way.

I consider this one of the most promising designs here. It’s the first option on this list I would look into for something really small and simple.

Metal SIPS homes work really well for mold and chemical sensitivities.

Make Your Own SIPS House

You can also make your own SIPS house easily and fast. This one below is made with Structall Building Systems panels. Another brand that I have seen sensitive people use is Permatherm.

These are also metal-EPS foam-metal and have an internal locking together system that allows them to quickly snap together.

In this design the panels are fully structural elements, there is no additional metal framing. The panels make up the walls and roof.

To create a long-term structure you would use siding on top of the SIPS and pour a cement slab to the same standards that you would use on a house.

But quick and dirty, you can throw up these panels fast and get away without siding if you don’t need it to last forever.

This is the fastest and safest (for both mold and chemical sensitivity) option on the list.

Art Span Inc

While I have no problems with the two above, I really like this Canadian company Art Span that makes Sip panels. It can be difficult to source the panels from the companies above and this one is easier to buy from.

They also have a couple of simple designs that are already kits. I like the little ice shack as well as the little houses.

I have a friend that built one and liked it.

Review of Boxabl SIPS House

The company Boxabl has created a metal SIPs 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.

First, is it good for chemically sensitive folks?

Yes, the basic structure of steel/foam SIPs is very safe for those with chemical sensitivities. That part has practically no offgassing.

They also use MgO board on the interior surfaces which is generally safe for most people with MCS. It’s not clear how that is attached, it’s likely glued on, which could be a problem for offgassing.

The flooring appears to be glue down vinyl, though they have described it in different ways. The countertops and tabletop are laminate. And the interior cabinetry is conventional. These three elements will contribute to offgassing of some VOCs, plasticizers, glues, and formaldehyde.

Is it a mold preventative design?

In general, metal SIPS are very resistant to mold because as long as the wall remains laminated they are immune to condensation problems. The waterproofing will depend on how well the seams are connected.

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. 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 vulnerable to water areas.

MgO and steel have not gone well together in the past. In Denmark, massive problems were caused when salts naturally leached out of MgO 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.

For more thoughts on this prefab I have a post on this company.

EcoSteel

Ecosteel homes are made of metal-foam SIPs, but this company uses polyurethane which usually has a little bit of offgassing (from the foam, blocked by the metal but it could come through at the seams).

They have a one bedroom that is already designed. It’s 165K which only includes plans and panels.

10. Hemp House

Hemp House Pods – a simple 8 x 12 structure meant to qualify as an ADU (without a permit) is made from hemp and a wood frame. Hemp may be mold resistant in certain climates. I would likely only use this in dry climates. My post on Hempcrete has more info.

I would have this reviewed just like all the others. I would use huge overhangs and I would look more closely at a foundation type that does not wick moisture up.

The cost does not include plumbing, electrical, or the deck.

They say they go up in a week.

11. Concrete AirCrete Dome

https://www.instagram.com/p/Bq2ydnqHspm/

I reviewed the AirCrete dome for mold resilience and I have a few thoughts on it. (Note this is different from AirKrete with a “K” insulation, though it’s a very similar material).

AirCrete domes are made of a mix of concrete and a foaming agent. You can use a natural dish soap like 7th Generation.

They were originally used in tropical settings and I do think they might this is simpler in climates that don’t require heating.

Mold Preventative Design of the Roofs

I do not like any of the designs that have multiple domes coming together creating valleys where water will not drain well. In some designs, debris is even accumulating in those valleys. I would only do single domes with as steep of a slope as possible.

No valleys where water and debris collect and soaks in. This is always best practice for mold prevention in houses.

The steeper the slope the better it will shed water.

The Challenge of the Exterior Coating Creating a Vapour Barrier

The exterior is coated with waterproof exterior stucco and then acrylic or similar concrete sealer.

The coating would have to be waterproof which creates a dilemma in heating climates.

If it’s waterproof then it is usually an exterior vapor barrier, which can cause condensation and mold in climates where heating is used. This is fine to use in climates where only cooling is used.

I might put this whole structure under a second roof, like a carport (or a souped-up metal roof like this house has). That way you don’t have the conflict of the need for a waterproof but also breathable sealant on the exterior of the dome.

You may also consider a sealer that sheds water but is breathable – a layer of concrete stucco sealed with sodium silicate might work. Just like polished concrete which is vapor breathable but should shed water. Consult with a building science expert to work this out.

Can Concrete go Moldy?

Conventional wisdom is that concrete cannot mold because it’s not organic. As a mold-sensitive person, I would say every basement, most slabs, and almost every concrete building in the tropics shows otherwise.

Mold can grow in anything porous, I have found.

Slab Must be Detailed Right for Mold Prevention

It’s also incredibly important to detail the slab right for mold prevention. Slabs are very prone to going moldy in all climates and are rarely detailed properly.

Because slabs are made of concrete and the dome is concrete you also have to take extra precautions with the slab and site details to not have wicking up of water from the ground up through the structure. This could easily happen in rainy climates.

The final flooring over any slab also needs to remain breathable to the inside in best practices for mold prevention. If the slab does take on water through wicking or through water coming in through the sides it needs to dry up.

Only polished concrete, tile (including stone tile), or earthen clay floors should be used as the final floor.

Does the AirCrete Dome Work for Extreme Chemical Sensitivity?

I think this dome would work for many people with MCS.

Admixtures are used in the concrete, you would want to check those out.

The foaming agent can be a non-toxic soap if you tolerate one of those.

The interior can be finished with natural plaster which does not contain additives.

The exterior finish needs to be looked at carefully, synthetic stucco might not work for everyone who is chemically sensitive. That won’t work in most heating climates anyway. Sodium silicate is considered safe for the chemically sensitive.

The slab would have the same concerns as all slabs. You don’t have to use rigid foam in the slab in many climates, but you do need a thick vapor barrier like Stego. It needs gravel underneath and proper grading.

A polished concrete or tile floor works well for chemical sensitivities.

You can find the workshops and the tools needed to create the concrete foam mix at DomGaia.

12. Container Homes

I have not been a fan of container homes in the past because the exterior metal envelope creates a really tricky situation for condensation in every heating climate.

More on that below, but if you are somewhere where you only use AC or no heat or AC this can be just fine.

When I saw that a company is making exterior insulation for shipping containers this changed my mind on the topic. The foam contours to the container and insulating it on the exterior eliminates the condensation issue.

You will still have to detail around the window and doors, and make the steel envelope airtight (I would try to weld all seams) but I really like this idea.

A Note on Exterior Metal and Fiberglass Shells and Mold Prevention

A prefab house that has a metal or fiberglass shell that does not have a rainscreen system is extremely difficult to insulate in most climates where houses are heated. This includes container homes.

“In a cold climate during the heating season, moisture vapor inside a building is driven outward into exterior walls. When it reaches a surface that’s below the dew point, the vapor condenses into a liquid.” (source).

In this case that “surface” where moisture in the air condensates is that metal or fiberglass shell.

To try and work with this problem you need airtight insulation. This could be 2 part closed-cell polyurethane spray foam insulation. This offgasses too much for most people with chemical sensitivities. It also causes the challenges of exterior leaks going undetected. Arched Cabins has a nice design because there are no seams or permeations. The challenge here is when spray foam pulls away from the metal or fibreglass.

The second strategy is to use rigid foam insulation and make it airtight. This is also tricky. Foam can be taped or sealed with caulking or 1 part canned polyurethane spray foam, but it’s difficult to keep it airtight. And any gap of air behind the foam can have air with enough moisture to condensate in some climates.

Mold Preventative Design

Options:

In heating climates, it’s easier to have a well-designed wall system that has the proper air barriers (likely no vapor barrier), and a rainscreen – in short, built like a regular house with all the complexities of the wall system but with great attention to design and execution of detail.
A monolithic wall – I tend towards simple buildings that have fewer areas where mistakes can be made. Monolithic walls (a single wall, made of one solid material) is easier in this sense. Log cabins, solid concrete walls, and solid earthen walls are examples. This doesn’t mean they will work in any climate and are foolproof. You still need a building science expert (like an architect) to design the system as a whole and make sure that the wall type is properly designed and executed and well maintained.

Corinne Segura is a Building Biologist Practitioner with 8 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!

Using Ozone to Kill and Denature Mold

July 6, 2019 by Corinne 77 Comments

The Effectiveness of Ozone Generators on Mold, Mycotoxins, Fragrance, and Smoke

Ozone kills and denatures mold on surfaces, and breaks down many VOCs and odors such as perfume. It can also remediate smoke smell in certain materials.

Ozone has also caused a lot of damage, not just to the breakdown of certain materials in a home, but it seems to exasperate some toxins, causing many people to not be able to return to their house for a long time, or ever.

This post contains affiliate links to relevant products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you.

Please take full responsibility for your safety when using ozone. Make sure you read and understand all the precautions in this post. Full disclaimer is here.

This post has been reviewed by Tim David, HVAC professional with 30+ years experience.

Does Ozone Denature Mold and Mycotoxins?

[Read more…]

The Best Air Purifiers for Mold – A Review of PCO

January 3, 2019 by Corinne 142 Comments

Updated Winter 2022/2023

PCO Air Purifiers – Which Ones Reduce Mold and Which Ones are a Scam

Photocatalytic oxidation (PCO) is a technology that breaks down mold, VOCs as well as some pathogens.

My interest in these air purifiers comes from first-hand accounts of this benefiting homes with low levels of mold and volatile organic compounds (VOCs), and from the studies showing the eradication of mold and mycotoxins.

I am really excited about this technology as something that can safely break down mycotoxins and odors. Some people may be interested in its effects on breaking down viruses and bacteria as well (including SARS-2).

What is PCO?

In photocatalytic oxidation, UV light hits a catalyst, usually titanium dioxide, creating hydroxyl radicals (OH) and superoxide radical anions (O2–). These molecules bind with and break apart pollutants into harmless molecules.

Best for Mold, Not VOCs

Right from the first version of this article which I published in 2017, I qualified PCO technology as best for mold reduction, not for VOC reduction. I have a different post on the best air purifiers for VOCs.

The reason is that in real-life circumstances the chemical breakdown of VOCs is not a simple linear process. Byproducts like aldehydes can be (and often are) produced as an intermediary product of PCO.

With a high amount of hydroxyl radicals in a closed chamber experiment it will almost certainly break everything down (with enough time) into harmless molecules, but in a home with relatively high VOCs, the results could look different.

Brands Under Fire

It has not surprised me (or really concerned me) that big brands have come under fire for some of their claims. What did shock me when I did the initial research is that smaller air purifier companies get away with outrageously false claims since no regulatory body even has time to get to them.

I would say most companies are exaggerating claims. My focus was on the technology itself, and what studies based on that technology show us, and to remember that there are only a few types of air purifier technologies out there – their claims need to fall into one of a handful of categories.

What About HEPA?

HEPA filters do capture some mold spores and this article does include filters that include both PCO technology and HEPA, though the main focus of this article is on PCO.

If you’re looking at HEPA filters that don’t include PCO, and filters that help with high levels of VOCs, the post on filters for VOCs will be more relevant.

My recommendation is based on the most affordable and effective products that I have found. Upon purchase, I earn a small commission through affiliate links at no extra cost to you.

1. Vornado – The Best of Inexpensive PCO Air Purifier (What I’m Using)

I use the Vornado air purifier. The Vornado PCO375 and PCO575 are the PCO air purifiers with the best value. (At around 350 and 400 dollars, respectively).

They have true HEPA and activated carbon in addition to UV light and titanium dioxide. Most PCO units are much pricier or don’t include all three air purification methods.

True HEPA and activated carbon capture dust, pollen, pet dander, smoke, bacteria, mold spores, dust mites, and odors including VOCs.

PCO and carbon are the main technologies used to reduce odors and VOCs. (Ozone can as well, but it is very risky, I have a post all about ozone).

PCO actually breaks down molecules including molds and mycotoxins. I like that it has all three main air purification methods for a good price.

Why I chose this unit:

The PCO component has true UV and titanium dioxide
Respected brand name
Noticeably brings down odors in new apartment and new cargo trailer
Has a 10-year warranty
Replacement parts are reasonably priced ($25 bulb every year, $35 titanium dioxide screen every 5 years – for the PCO related parts)
Does not put out ozone

What I don’t like about it:

What I don’t like about it is that the unit itself offgasses a little bit (I am extremely sensitive). Not everyone thinks so or would notice this. After two weeks I found it to be good. I’m happy with it offgassing within two weeks. (Anyway, all air purifiers offgas a little).

The other drawback is that the amount of titanium dioxide is quite minimal so it may not be producing as many hydroxyl radicals as other PCO units. I am going to go with Molekule if I try another brand of PCO air purifier (more on them below).

A photo from the top looking down on the Vornado air purifier in white with black grills on the top

Model 375 versus 575

The difference between the two sizes is that the PCO575 has a lower low speed and a higher high speed. The PCO575 has 2x the HEPA and 2x the activated carbon of the PCO375.

They both have the same PCO technology – so if you want to increase the effectiveness of the OH molecules in a large space you would want two of the PCO375 instead of one PCO575.

The 375 has a 113 CFM on high, 28 on low.

The 575 moves 156 CFM and is advertised for 258 sq ft., which would get you about 5 ACH in that room.

Buy the Vornado PCO375 and PCO575 from Amazon.

Some other PCO units are more or less the same unit re-branded: Continental Fan CX1000, Catalytic Pure Air, Field Control Trio / Sun Pure SP-20C. They seem to use a very similar PCO catalyst style to the Vornado with a titanium dioxide plated metal screen.

What are Air Exchanges Per Hour (ACH) – Air exchange per hour is how many times you are “replacing” the air in the room per hour, this is a key area of comparison with air purifiers.

ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends a minimum of 4 ACH for patient rooms in hospitals, 5 for intensive care units, and 25 for operating rooms. For the purposes of those extremely sensitive to mold and VOCs, we want about 5-10 air exchanges per hour.

To maximize how much air in the room the air purifier can process, put it in a central location.

How do You Calculate the ACH From a Unit’s Specs – You always want to find the CFM of the unit. The CFM is the capacity of the unit to move air – how much air it moves through the machine. CFM stands for Cubic Feet Per Minute. You need the CFM to calculate ACH. I made two calculators to calculate ACH from CFM and CFM needed from the room size and desired ACH.

2. GermGuardian – The Best Small & Inexpensive Unit

Another brand that is very affordable and also incorporates HEPA, carbon, and PCO is GermGaurdian.

I have heard of people using it in trailers and being happy with it. At $89 it’s a steal. And it has 5.5 ACH in 171 sq ft.

But this is small and simple, I would only use it in tiny spaces if you can’t afford something better/bigger.

Buy the GermGuardian on Amazon.

3. Molekule – Top Overall Pick

If I had to go back and pick one right now, I would choose Molekule.

This is a slightly different technology called PECO.

Here is a summary of their studies – very promising results on eradicating mold. The data they showed me showed it worked better on mold than PCO.

Their newest filter option also contains HEPA and some carbon.

This company has well-respected big names behind the design. The inventor of Molekule is the person who discovered PCO. He has an impressive resume.

I will be trying this machine out as I think it is very promising.

The warranty started as a 1-year warranty but now it is a 2-year limited warranty. The company has been around since 2016.

Molekule Air Pro

The Pro is the biggest model, it’s is advertised as cleaning up to 1000 sq ft. You will get 1 ACH in a room of 1000 sq ft with 8.5 ft ceilings.

It goes for $1,199.

The Molekule Pro does come with a basic particulate filter but that is not the primary function of this unit. That is likely to keep the other filters and components free of dust. If you want to add more particulate filtration they do now offer a HEPA filter for the Pro.

The replacement filters for the Pro are $150 which lasts about 6 months, so replacement filter costs are high.

Molekule Air

This is their original model. They state it cleans up to 600 sq ft. You get 1 ACH in a room of 600 sq ft with 8.5 ft ceilings.

It goes for $998.

The replacement filters are about $200 per year.

Molekule Mini

The new Molekule Mini provides 1 air exchange per hour in 250 sq feet. They offer a HEPA filter option for the Mini.

It sells for $499.

Which Size Should You Choose?

In a room that is 15 by 15, the biggest model would get you 4 ACH. That is a good number of air exchanges to aim for if you want a high level of air purification.

Here is my calculator that helps you size an air purifier for your room based on how many times you want to overturn the air in an hour.

If you can afford it, and if design is important to you, Molekule with HEPA is my top pick.

Buy from the Molekule website or Amazon.

Other Contenders

1. Air Oasis – A Review

The Air Oasis Ionic Air

The Ionic Air has three components, one, a PCO component – germicidal UV light and a catalyst that is made of different metals to produce hydroxyl radicals; two, a bi-polar ionizer; and three it produces ozone (either through the UV light or via the ionizer).

The 3000G3 model is rated for 3,000 sq ft and only moves 11 CFM of air. 3,000 sq ft at 11 CFM is 0.02 air exchanges an hour. That is very little air movement. (I am using 8 ft ceilings in my calculations of CFM to ACH). But that’s not important for the ionizer and ozone components.

Technology – PCO

The company states that the PCO process creates “ionized hydroperoxides”. I have seen other PCO air purifier companies make this claim. This seems to me a confusing way to describe PCO which primarily produces hydroxyl radicals and secondarily produces superoxide radical anions (O2–).

Whenever I’m reviewing an air purifier I always keep in mind that there are only a small handful of possible technologies they can use. When it sounds like they have invented something new it means it’s time to look into their claims and see which of the few main technologies they are really using.

Technology – Biopolar Ionzation

A bipolar ionizer produces negative and positively charged ions that can cling to pollutants, dropping them to the ground where they can be cleaned and they might be able to break apart (chemically) some types of pollutants or biologicals. This type of ionizer can sometimes be advertised as cold plasma ionization (source).

Technology – Ozone

The air purifier also relies on low levels of ozone for air cleaning technology. You can have one made without the ozone production component but that seems to be a key component of its air cleaning abilities.

I personally do not consider any level of ozone, unless it is minuscule, to be safe to use in occupied spaces.

Final Thoughts on Air Oasis Ionic Air

I know this brand because mold doctors promote it. I was surprised when I dug into it to see how little air moves air through it, and that it gives off ozone. It was not approved by CARB at the time of writing the original version of this article (2017). It is now meeting California levels of safe ozone (CARB). (Though the upper limits of ozone in CARB are too high for me, personally).

Since the time I first wrote this article, it seems the company is much more clear that this is an ionizer. How much air it moves is not that central to an ionizer (but is for the PCO component). I’m a little wary of bipolar ionization which Dr. Marwa Zaatari, Mechanical Engineer, claims is not necessarily effective.

It has a 3-year warranty and the replacement parts are $80 every 2 years.

Air Oasis iAdaptAir

The newer iAdaptAir is similar but claims to produce zero ppm of ozone. This is something I would be more likely to try.

It contains a HEPA filter, a carbon filter, PCO technology, and a bipolar ionizer.

Most ionizers give off ozone but it is possible to produce ions with minuscule ozone that does not register against background levels.

It comes in three different sizes for $399, $599, and $799.

The small, covers 250 sq ft and has a CFM of 58 (2 ACH per hour), the medium, covers 550 sq ft with 151 CFM (2 ACH per hour), and the large covers 850 sq ft with 237 CFM (2 ACH per hour).

This is really a great little unit if you want HEPA, carbon, PCO and you want (or don’t mind) the ionizer.

Air Oasis Versus Molekule – A Comparison

I personally would not use the Air Oasis Ionic Air with ozone so I will compare Molekule to the ozone-free iAdaptAir.

The main comparison that I can’t quantify is the strength of the PCO component – just how many hydroxyl radicals do they produce. Molekule has a good reputation for working well even before the HEPA option was added.

On the other hand, iAdaptAir has a really good value for what it provides. The only downside for me is I’m not a big fan of bipolar ionization as I have my doubts about its effectiveness and I tend to be sensitive to ionizers.

Both are good choices, however.

Here’s the comparison:

Molekule Air

Modified PCO technology
HEPA filter is optional
No ozone
CFM ~80
Costs $998
Replacement filters $200 per year

iAdapAir Medium

Modified PCO technology
True HEPA filtration for particulates
Some carbon for absorbtion of VOCs
Bipolar ionizer
No ozone
CFM 151
Costs $599
Replacement filters $100 per year

2. Airocide Air Purifier Review

Another popular PCO machine that has been around for a while is Airocide. The APS 300 has a CFM of 40.

I like that the website has studies confirming that it doesn’t give off ozone. They used to have a short case study on breaking down mycotoxins when this article was first published in 2017 (though I can no longer locate it at the end of 2021).

It looks cool which is a plus.

The claims about removing dust, dust mites, and allergens do not seem all that accurate (especially after seeing what Molekule just went through with the FDA suit) since PCO machines do not filter particulate pollutants (according to the EPA).

It had a 5-year warranty when I first wrote this article, now it is a 2-year warranty. It costs $100 a year in replacement parts.

Why did I rule it out for myself: Most of the PCO machines do not include HEPA and activated carbon like the Vornado. This is a lot more expensive than Vornado or Molekule, but doesn’t move as much air.

FDA Approval of PCO Machines

The FDA approvals I have found are one for a PCO machine involving titanium dioxide (it proved to destroy some bacteria, viruses, and mold) for specific commercial uses.

The Airocide, Odorox, and Molekule Air Pro all have FDA approval as type 2 medical devices for use in hospitals. The first two use titanium dioxide and UV technology.

The FDA approval cannot be stretched to make safety or health claims on any device that deviates from this technology or has unknown additional technologies.

HiTech claims to be FDA approved, I can find no evidence of that. Anyone can search for FDA approvals here.

Adverse Reactions to PCO Hydroxyl Generators

I have heard of people having bad reactions to HiTech. I have heard only one bad reaction to Airocide, and a couple of bad reactions to AirOasis both the ozone and non-ozone types.

I do not know what accounts for these bad reactions. It does not appear that there is an ozone issue (apart from AirOasis). Dr. Daniel Cagua Koo has also noted that some patients simply don’t do well around this technology.

Since writing I have heard of some bad reactions to Molekule with about 50% of sensitive folks buying it being happy with it, and the other half not, and one bad reaction to Germ Guardian.

It is possible that PCO is creating harmful byproducts in high VOC buildings.

If you are in high VOCs I would focus on a filter that has a lot of carbon like these. If you have MCS focus on these options I review here.

My interest here is for a house with extremely low VOC levels and already extremely low levels of mold. And the hope here is to keep the air as low in mold as possible.

I would love to hear from more people who have tried these other brands. Let me know if you have had good results or a bad reaction to a PCO machine.

Do PCO Machines Give off a Burning Smell

According to Airocide, the UV bulbs themselves emit a bit of a burning smell at first. They burn theirs in for two days, but sensitive people can smell it for up to a week.

The Vornado PCO had a very slight burnt smell at first which seemed like the smell of carbon.

Airocide made a statement that mold does not produce a smell when broken down by OH molecules.

HiTech states that the burning smell is mold/mycotoxins breaking down. I have found no evidence for this claim. A HiTech user also stated that the UV lights have burnt right through the “reactor pads”. This is consistent with a theory that the UVC lights are burning the “reactor pads” and causing a smell.

Corinne Segura is a Building Biologist Practitioner with 8 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!

This post is not sponsored.

This post was written with the technical assistance of an electrical engineer, though the opinions and conclusions are my own.

Building a Mold-Free Tiny House

December 24, 2016 by Corinne 17 Comments

Building a Mold-Free Tiny House

This article will discuss preventing mold in tiny homes that are custom built.

Usually on wheels, but much of this could apply to lane houses and other tiny homes not on wheels (though I don’t discuss foundations here). This will apply to some prefab but not all types.

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

Major problems with tiny houses that cause mold:

Very few people hire an architect, engineer or other building science expert to design the system.
Many tiny home companies are new and the builders lack experience or are not experienced enough in all aspects of building (from plumbing to roofing, to installing heat pumps, to insulation, and moisture management).
The DIY movement is a problem because the size of the home makes it seem like you can do it yourself, yet you still need all the knowledge of all the contractors: electricians, plumbers, roofers, architects etc. to build a house. The size of it does not necessarily make it simple!
DIYers ofter learn from other DIYers via the internet, copying others’ mistakes.
The movement is new and it can take 10 years for some mold problems to show up.
Most tiny homes do not need to follow building codes. Almost anything goes in most places, resulting in poor building practices.
Homes are built in one climate and shipped around the US and Canada to other climate zones where the moisture management system may not fulfil its function. Owners may also move the house to a different climate zone.
Only one year warranty on many houses will not be long enough to cover mold issues.
Many tiny homes I have seen have simply invented wall systems that would never be used in a regular house.
I have seen major problems with the moisture management systems such as vapor barrier errors, and smaller but still problematic practices like lofts built with mattresses right on the floor with no ventilation, and inadequate exhaust fans.
Lack of attention to detail that comes from inexperienced builders or those not concerned about mold.
Building by prioritizing non-toxic materials over building the correct moisture management system (because you remove or replace a part of the system with something non-traditional).

Condensation on my tiny house roof cavity

When I first set out to build my tiny house I was mostly concerned with choosing healthy materials that were 0-VOC.

It was only after I took the house apart (almost completely) to fix the problems my builder made, that I realized the extent of knowledge needed to build a mold-free home.

I thought you just leave the construction details up to the contractor, but my builder (Ben Garratt, Tiny Healthy Homes) made a long long list of mistakes.

I lost 100K dollars, my health and housing stability needed to stay healthy and on budget.

From interviewing and working with dozens of contractors in my area, I have found one out of a few dozen who was knowledgeable and detailed enough to renovate the house in the correct way.

The two most important aspects of designing a mold-free tiny house are:

Have an architect (or other building science expert) who specializes in mold prevention design the moisture management system. This is everything from the wall system to the roof, the floor, and the ventilation. They will also need to take into consideration which materials you can and can’t use to design the system. Take the time to do this in detail before you hire your tiny home builder. I can help with consulting on materials at this stage because the architect needs to know which materials can and cannot be used/tolerated.
Extremely detailed supervision. I have fixed everything from my bathroom fan to my walls and roof. Taking my attention away from the project for more than an hour led to mistakes by the contractors who simply do not care about mold prevention. Even if you find a good owner, that person leaves the work to his laborers or subcontractors who are not well supervised. Here you can either hire someone extremely competent to supervise, or you can supervise yourself. If you supervise yourself, take the guidance from your architect, and learn the basics in order to follow those guidelines (or you will be calling him or her every few hours). Make sure the builders have a very detailed plan of how you want things done so that when you come into supervise you are staying on plan. There may be a clash of egos here, but you need your house done right and most contractors do not have the right skills.

Of course, choosing the right expert to guide you is also important, so before you do that you should be aware of a few different ways to manage mold that are popular and get a few opinions before you decide on hiring someone.

Here are a few different systems:

Passive house design – Passive house design is a very detailed system that uses a lot of calculations to manage the moisture in a scientific way. You can check out 475 to learn more about this.
Breathing walls
Walls with vapor barriers – Learn the basics on vapor barriers and what smart vapor retarders are
Wood frame houses versus metal-framed houses.
Building with SIPs.

Here are a few terms and ideas to learn about so you can follow along with your expert:

Flashing of windows and doors – the instructions on this are fairly simple and yet they are often not followed precisely (they need to be!)
Taping house wrap – there is a controversy about whether to tape the horizontal seams
Rainscreens
Solar vapor drive
Vapor barriers and condensation
Insulation types and their permeability
Perm rating of a material/barrier
Air barriers versus vapor barriers
Ventilation – proper exhaust fans, ERVs, HRVs, and dehumidifiers
Exterior foam insulation method
Steel frames versus wood frames
Zip systems instead of house wrap

Do not attempt to become an expert on these topics from reading about them online. Though there are more resources and online courses available online now.

You want to be informed so you can choose a good architect and understand the system they are designing for you.

You may also need to learn enough to supervise the build.

Some basic mistakes you can avoid to keep your house as mold-free as possible:

Window and door flashing not done in a detailed way. Also, beware of 0-VOC peel and stick window flashing which doesn’t fit most codes and is not recommended by the companies themselves for the rough openings. I have also seen windows flashed with house wrap tape and not proper peel and stick flashing.
Silicone and other caulks skipped where needed on the exterior due to chemical sensitivities.
Having air leaks into the wall cavity.
Housewrap not applied to spec – including the overlap and how it is taped.
Roof not vented properly (there is some debate here between passive house design and most builders) or double vapor barrier issues in the roof.
Putting the vapor barrier on the wrong side.
Planning the house to be used with heating but not planning for AC.
Exhaust fans over the stove that don’t vent to the outside. Exhaust fans in the bathroom that could leak moist air into the ceiling. The fan I used is pictured (doesn’t leak moist air). (As an Amazon Associate I earn from qualifying purchases through the Amazon links.)

Inventing a new wall system that is not normally used. Make sure you understand your wall system and which direction it dries to. Don’t skip on things like rain screens (if that is the system you are using) just because it is a tiny house.
Not having a professional plumber install your plumbing system. Or reusing old plumbing pieces that could fail on you.
Pipes not designed and winterized for the climate causing them to freeze and burst. Not providing the cold and hot water a low point to drain outside. If the power goes out you will need to drain them. You may also want to drain them if you are away.
Using wood that doesn’t hold up well to humidity in the framing.
Putting your mattress directly on a solid surface with no ventilation under it (use slats or a box spring).
Using natural latex. See my warning here.
Not using a properly sized drainage line on a heat pump. Know how to flush it out, this tends to get clogged with mold.

Corinne Segura is a Building Biologist with 8 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!

Simplified Mold Testing Overview – Pros and Cons of Different Methods

October 25, 2016 by Corinne 7 Comments

First I want to talk about the most reliable test which is how you feel in the house compared to other places. Unfortunately, this is not always as simple as it sounds to execute. There are different ways to undertake this experiment.

Some have to start in a tent, car or trailer outside their house, but you need to be 100-200 ft away from a moldy house, and your outdoor air quality might be a problem as well.

The next option would be to stay somewhere where other people recovering from mold illness (and MCS) have felt better. This could be a campground, KOA cabin, Airbnb or other rental. I have a lot more details on this in my post on the Locations Effect and Mold Sabbatical.

Once you have gotten “clear” and done some recovering you might be wondering how do you test a house to find out if it’s good? Some people can walk into a house and know if it’s good for them. But even the most sensitive people usually need to request to spend 3 nights trialling the house.

This is not always an option, but you should ask. Usually, people sleep better in a house that is mold-free, but me and other CIRS patients have found that there is some mold that puts you into a zombie sleep where you sleep more (and then get sicker). So even a three-night test can be tricky.

This post contains affiliate links to relevant products that I use and recommend. Upon purchase, I earn a small commission at no extra cost to you. Disclosure: I was given the Tape Lift test to see if I liked and recommended it.

Mold Testing

It can be a good idea to verify the house is safe with mold testing. The most common test for CIRS (mold patients) is the ERMI. It is highly recommended by Shoemaker certified doctors as the test to use. The range of the ERMI scores goes from minus 10 to positive 20. You need a score or 2 or lower to be treated and recover from mold illness according to Dr. Shoemaker.

Other types of mold tests can also be useful. A tape lift will get you definitive results on visible mold. I look at the options below. This is a very simple overview just to give you the general idea of what is out there in a way that is not overwhelming – you may want to look more into each of these different methods.

Please note that my sources were biased towards mold advocates Lisa Petrison from Paradigm Change, Greg Muske from Biotoxin Journey, Dr. Shoemaker and Cheryl Ciecko, an architect who specializes in mold prevention.

I have attempted to cross-check their information. However, going with information from the companies that do house inspections can be biased and contradictory. (All sources at end of post, which you can read for more detail).

Let’s Compare Them:

1. ERMI

Cons

Doesn’t work well in brand new houses.
You need dust that has settled for a while (wait 4-6 weeks to re-test an area).
Having very little dust or a high amount of dust can skew results.
Having a high amount of outside dirt inside can skew results. Having high or low outdoor spores counts can skew results.
May not be an even distribution of spores throughout the house if mold is only coming from one place and the house is large.
It is known to miss major mold problems when people are very sick in their house. Similarly, after a remediation, a CIRS patient can still be sick from the mycotoxins left behind despite a low score.
“Only the ERMI and HERTSMI have been associated with sequential activation of innate immune responses, not air testing.” Dr. Shoemaker. Meaning it is the only test that he found that is consistently in line with lab results for CIRS, despite its drawbacks.
The vacuum method can pick of heavy spores like Stachy and the Swiffer method can also be used to pick up places with accumulated dust that has been there for 4 months. John Banta always tries to use the vacuum method over the swipe method.
It’s pretty affordable at $300. You do it yourself. The lab recommended is Mycometrics.

HERTSMI-2

Similar to ERMI but tests for a handful of molds most commonly associated with water-damaged buildings. It is cheaper than ERMI. I would go for the full ERMI and you can still calculate your HERTSMI value from that. Shoemaker certified doctors will consider your HERTSMI score as well as ERMI score.

2. Tape Lifts

Cons

You need to have visible mold.
It assists you with what type of mold it is and not how widespread the problem is.

Pros

Tells you what kind of mold you have when you have a visible sample.
Allows you to know if this is a toxic mold.
You can do it yourself.
It’s a cheaper way to test for visible mold.

I used this DIY Tape Lift to test a few areas in a house I go into often. The results came back showing me what type of mold it was. It confirmed that the mold was one that is toxic that comes from water damage. Though you need to get a decent amount of mold on the tape otherwise your results will just show scattered pieces.

3. Spore Traps (Air Test)

Cons

Needs to be taken near the source, so you have to know where the source is.
Shoemaker says: “The industry standard of sampling the air for spores is not an acceptable substitute for many reasons. One of the main limitations is that over 99% of the particles that carry the inflammagens from water damaged buildings are smaller than 3 microns. Spore traps can only detect particles that are larger than 3 microns and therefore, miss over 99% of the inflammagens.”
Spore traps identify round, intact spores. So they will not catch evidence of past problem that have left mycotoxins.
Can miss/underreport certain heavy species like stachy.
Expensive.

Pros

The test is more standardized than tape lifts, swabs, cultures, and mold-dogs, they claim.
It is the most widely used mold test.
You can compare inside and outside air.

4. Dishes

Cons

Hard to know where to place the dish to get capture the mold if you don’t know where the mold is coming from.
Doesn’t get you an accurate relative reading since some mold is harder to catch and some proliferate faster in the dish than others.
Stachy is a slow grower compared to other molds in the dish.

Pros

Can be used in multiple places to compare and for general observation.
Can give you more details on the exact type of mold than other tests.
Inexpensive.
John Banta does a culture of the dust used for ERMI to compare and get more details

Here is one you can do yourself.

5. Mold Dogs

Cons

Can only detect a handful of molds.
Hard to know if they are well trained, look for good references for the company.
They can’t tell you if it’s high amount of mold or a trace from after remediation.
The dog can only sniff in areas where they can reach.

Pros

They are good at finding the source if it is within their reach.
The dog can smell both live and dead mold.
You can pinpoint the area where you need to do further testing.

6. Mycotoxin and mVOC testing

Cons

There is controversy around the accuracy of this testing.
Not widely used.

Pros

Test the levels of mycotoxins and other VOCs in the air.

Here is a company that does this kind of testing that is recommended. It goes to an AIHA accredited lab.

Since I first wrote this post, EMMA test by Real Time Lab has become more popular. This tests for 15 mycotoxins using the dust from your AC or heater filter.

Sources:

http://biotoxinjourney.com/mold-testing/
http://paradigmchange.me/testing/
https://www.nachi.org/tape-sampling-mold-inspection.htm
http://healthybuildingscience.com/2013/02/14/mold-testing-air-quality/
Public postings by Cheryl Ciecko (Architect)
John Banta interview
Dr Shoemaker Q&A

Corinne Segura is a Building Biologist with 8 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!

An All Metal Tiny Home

July 30, 2016 by Corinne 12 Comments

Here is the tiny house being built for my client right now by Tiny Green Cabins. The house is made with no wood whatsoever, including plywood and OSB! This is made for someone who cannot tolerate wood of any kind. She is extremely sensitive to offgassing and mold.

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

Here are the specs:

Size is 8’ x 20’ x 12’-5 1⁄2” tall, with an approximate weight of 9k GVW.

The trailer is a custom welded steel channel beam trailer.

There are options for the paint used on the trailer.

Steel Underbelly 2 x 4, 16 gauge joists.

The cold-formed steel joists are bolted to the trailer frame.

Walls are framed with 2 x 3 18 gauge cold-formed steel studs @ 19.2 on center, fabricated with screws and welded connections.

Rain screen (furring) is made of metal (Rain screen in important in case moisture does get into the walls).

Roof structure is 18 gauge cold-formed stacking above joists, fabricated with screws and welded connections. No wood used!

The loft has metal floor sheathing. The kitchen has a stainless steel sink with metal cabinets and countertops. Other countertops options can be considered.

For the bathroom there are different options – you can have RV hook-ups or a composting toilet and greywater system. (Nature’s Head is the best composting toilet. Others like Sunmar have major issues.)

There are a few options for windows. I prefer aluminum, but they cannot be sourced everywhere. There are other options in my window post that people tolerate well. Typar zero-VOC window flashing is being used.

Fabral smooth painted steel to wrap the exterior walls, and Fabral “w” metal roofing for the roof. Metal at walls is riveted and steel roof and trims screwed. Fabral should be tested first to make sure the paint finish is tolerable. Other metal finishes are available with different brands.

Ceiling is corrugated steel

Interior walls are Fabral steel attached with screws. The interior comes in different colors, or can be painted later with metal primer and paint. Caulking is used to prevent water vapor from entering the wall cavity.
Metal flooring is 2 layers of 18 gauge steel layered. Foam is used as a thermal break and insulation.

Doors are metal and glass.

Insulation options are XPS foam or foil-backed polyiso. Foam is being used as exterior sheathing/thermal break as well. Other materials could be considered for insulation but rigid foam was our top pick here. Tyvek tape is used to seal the sheathing if tolerated.

They also used caulk on the inside side for an extra barrier to water vapor entering the walls. (This is a double vapor barrier – note the risk. Please consult with an architect if you can only tolerate metal and foam).

Heating and cooling a 12-15,000 BTU inverter heat pump, Daikin LV series or Mitsubishi hyper-heat models installed by an HVAC company is recommended. Other heating options such as wall mounted electric heaters or propane RV heater/AC combos (off-grid) could be used. Another propane option that is tolerable is a direct vent heater.

For a hot water heater, we are using propane on demand. This is the best way to go for water to keep the house to 50 amps or less.

Exhaust fans are very important in an all-metal house to keep the humidity as low as possible. In the bathroom, it should be exterior mounted as to not leak moist air into the ceiling. An ERV could be a good option if you have a composting toilet (this depends on your climate as well). In the kitchen, the exhaust fan needs to vent to the outside. A dehumidifier may also be needed if condensation forms on the walls or the mattress becomes damp (do not put a standard mattress straight on the ground).

For appliances, a propane fridge should be considered to reduce electricity needs (2-way or 3-way refrigerators can be good depending on your needs and if you are incorporating solar).

An apartment-sized stove can be used or else a small convection oven with a cooktop. If you can tolerate propane or alcohol stoves those can be considered for an off the grid house.

Flooring can be left as metal. Tiles can be considered although this would add considerable weight. Natural carpet or rugs can be considered as well to cover the metal.

Corinne Segura is a Building Biologist with 8 years of experience helping others create healthy homes.

Thanks to Luke Skaff, electrical engineer, for help on the technical aspects.

Always consult with an architect or engineer on moisture management in your building envelope.
SaveSave
SaveSave

How a Building Biologist Can Help you Create a Healthy Home

April 20, 2016 by Corinne 16 Comments

I am now certified as a Building Biologist Practitioner with the International Institute for Building-Biology and Ecology!

The Institute’s mission is “to help create healthy homes, schools, and workplaces, free of toxins in the indoor air and tap water, and electromagnetic pollutants.”

I hold a number of other certifications that can be found here.

My Main Areas of Expertise

1.

Digging deep into the toxins found in building materials to help even the extremely chemically sensitive with new builds and renos. I dig into testing, studies, and patents to find out what the companies aren’t telling us. I test out materials myself, and look to the experience of the most extremely sensitive for guidance.

2.

Attention to building science principles, to make sure your materials are compatible with your moisture management system. No compromises on performance that will lead to mold!

3.

Helping those extremely sensitive to mold and chemicals find safe housing. This may include analyzing photos of homes, choosing healthy locations, choosing healthy trailers or RVs, or help embarking on a mold sabbatical.

What is a Building Biologist?

Individual Building Biologists offer different services, but our aim is always to help you create a healthy home or work environment.

We look at how indoor environments can adversely affect health.

In order to create healthier indoor environments, we focus on building materials, building processes, indoor air quality, and EMFs.

Personally I have chosen not to consult or advise on EMF/EMR.

I do focus more intensely on digging deeper into toxins in materials as well as building science principles to help you prevent mold.

What does a Building Biologist do?

Some Building Biologists do in-home testing. They may come in with various instruments to measure mold, VOCs, and EMF/EMR.

My approach is different. I use an experiential approach. While we will certainly use scientific information that is available to choose safe products and prevent mold, the way that we go through the process includes your body’s reactions.

With the Mold Avoidance approach, pioneered by Erik Johnson and Lisa Petrison, your body will guide you through “unmasking’ and the ability to detect mold and other toxins. This will help you choose safer housing.

My Guiding Philosophy

I use hard science to investigate in detail what companies aren’t telling us about what’s in a product. But your body will ultimately be the lead in your healing.

I don’t believe in the bucket theory, but rather the master toxin theory.

I’ve been closely studying recovery stories for 10 years. The pattern I have seen and experienced is that when we avoid the master toxins (mold certainly being the biggest one but not the only one), that the body will tell you what to avoid in order to heal.

Building for the Extremely (Mold and Chemically) Sensitive

I have assisted with the following areas:

Choosing non-toxic materials for a new build or renovation
Building a safe a tiny house, trailer, or emergency structure
Remediating offgassing, fragrance, and other odors from buildings
Experience with which materials tend to work best for extremely sensitive individuals
Selecting non-toxic furniture and mattresses
Choosing the right water and portable air filter for your home
Choosing safe RVs and camping gear

My Credentials: To see a list of my continuing education courses & certifications, check out the full list here or on my Linkedin Page. Below is my certificate for the Building Biology course.