Here are some simple, small modular homes or shelters for the chemically sensitive.
The metal yurt from Clean Air Yurts is 18 inches in dimeter. The shell is made of glavanized steel coated in zine. 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 stucture. 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 inches in diameter and made of galvanized steel. There is room for a loft and it has louvers that can collect rain water 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 home around 10K but there is a big discount for non-profits who are purchasing them.
Did not hear back from them via email regarding the cost so not sure if these are available right now.
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 includes 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 floor plates, ribs, ridge beam, standard insulation R13, Super Span Roof Paneling (metal), trim and fasteners needed to assemble the cabin. This does not include the foundation, installation, interior, end caps, and delivery.
The 12×12 which has room for kitchen and bathroom is $2708 which includes the basic kit plus a fireplace thimble, Super Span Roof Panels color upgrade, and R25 insulation.
This is a simple, mostly metal kit that you could then customise to be chemical-free on the inside.
These cool domes are easy to transport and assemble and have a lifespan of 30 years.
They are made of fiberglass composite material which the company says does not emit an odour. Some sensitive people say fibreglass needs some time to offgas and others find it ok fairly soon after production.
The domes start at $7,500 for the 14′ model.