Updated in 2019
Simple, Small Modular and Custom Homes for the Chemical and Mould Sensitive
For individual help choosing the best tiny home or structure of your needs or a review of a tiny house company, you can contact me here for a consult.
Passive Home Tiny Homes
Besonwood is a high-quality passive home prefab company. This home pictured is 150 sq ft. The owner chose the stone facade but that would not be typical with their houses.
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 quality work and indoor factory conditions.
The metal yurt from Clean Air Yurts is 18 ft in diameter. The shell is made of galvanized steel coated in zinc. The door is metal as well.
You would need to build a foundation and choose materials for the exterior and interior, provide insulation and wiring and plumbing (if desired).
Though you could just leave it as a steel structure. The yurt can be assembled in one day and can be taken down and moved if needed.
The cost of the metal yurt is 10K
Grain Bin Home
These Grain Bin Homes are also 18 ft in diameter and made of galvanized steel. There is room for a loft and it has louvers that can collect rainwater if desired. Other options include solar panels.
It does not come with options for interior/exterior or foundation, so those would be up to you.
The homes are around 10K but there is a big discount for non-profits who are purchasing them.
Eco Built Systems makes little domes. They used to be MgO based and now it looks like they are focused on glass domes and pyramids. This company has been a bit of a moving target for the last few years.
They are being manufactured for distributors last I checked.
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 are $450 and that includes a 3-hour consultation. The metal parts are $2000-2500 and the wood would come to around 5-10k, not including materials for wiring and plumbing.
The basic kit for Arched Cabins includes kits include 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 are no leaks. In this design, you can use spray foam insulation without worrying about exterior leaks getting in behind.
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.
These cool Intershelter domes are easy to transport and assemble and have a lifespan of 30 years.
They 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 domes start at $7,500 for the 14′ model in 2017.
I’ve looked into these in detail so contact me for a consultation if you are interested in how to make these non-toxic and for more details and tips.
Simple Wooden Cabins
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.
It is $6500 CAD for a 14 x 14 foot cabin. They are produced in Canada.
A SIPS House
The Nomad Micro is a 10×10 metal SIPs house. It can be made to be very non-toxic. They are 28K CAD (which is actually quite pricey). You need to add: shipping (From Vancouver BC, platform or slab, installation, wiring, heat, plumbing, hot water heater. There is an option to complete the inside in a non-toxic way. My most sensitive friend tested the SIPs and thought they were good.
Nomad has stopped production of the 10 x 10 and only produces the 13×13 now. They have also changed the basic design of the units since I first posted on this.
Amish Built Wooden Home
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. They can be moved though they are not on wheels. This one is 400 sq ft and was only 14K!
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 proof in certain climates. The cost does not include plumbing, electrical or the deck.
The houses are 15K and they say they go up in a week.
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 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
- 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 as maintained.
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Corinne Segura is a Building Biologist with 6 years of experience helping others create healthy homes.
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