A Tiny MCS Home in British Columbia
One woman with MCS had a tiny house built of safe materials and then transported it to a place near the coast of British Columbia, Canada.
Keywords: tiny house, tiny home, MCS, multiple chemical sensitivity, portable housing, composting toilet
The floor plan
The house itself is 20 x 8 ft (6.5 x 2.5 meters), which is 160 square feet (16.6 m2) of living space.
With such a small space, it is essential to use an efficient layout. The floor plan is one large room, with a kitchen in one end and a tiny bathroom (2½ x 8 ft, 75 x 250 cm) in the other end.
Above the kitchen is a sleeping platform (loft) with room for a queen-sized mattress. Access to the loft is through a series of steps: the first two steps are on the side of the kitchen cabinets, the third step is a landing on top of the cabinets. The rest of the steps are a vertical ladder.
The owner bought a set of plans from one of the tiny-home vendors and then modified them. In such a tight space, even minor changes can have a big effect on other parts of the plans, and any changes mean the list of materials has to be recalculated. Non-toxic materials were substituted for the standard materials, such as plywood and drywall.
The builder specialized in natural home construction, such as cob and earthships, but this was his first tiny house.
The house was built on a 10,000 lb (5 ton) flatbed trailer. Natural materials weigh more than conventional materials, and well into the construction phase they realized they had to save some weight to avoid overloading the trailer.
The structure is wood-framed, using four-inch (10 cm) poplar studs in the walls. The studs have embedded steel straps to keep the walls stable during transport and in high winds.
The outside siding is cedar, which does not need to be painted and is naturally resistant to rot. It was the plan to mount the siding over magnesium oxide (MgO) boards, but they were omitted to save weight.
The insulation in the walls is cotton, with an insulation value of about R-14.
The inside walls are covered with magnesium oxide sheets with joint tape and Murco M-100 joint compound over the seams. The wall boards are covered with a clay plaster over a wheat paste primer. A sealer (AFM Penetrating Waterstop) was used to protect the plaster in the kitchen area.
The walls include a vapor barrier, which should be placed on the warm side of the insulation. In this case it was installed on the wrong side of the insulation, and it will have to be corrected to prevent condensation and mold growth inside the walls.
The floor and ceiling are poplar boards (tongue & grove). Behind that is a vapor barrier, cotton insulation and then house wrap (air barrier). The roof is aluminum. The floor and ceiling are better insulated than the walls, though the owner is not sure by how much.
The floors were stained with a natural milk paint, which was difficult to work with.
The kitchen cabinets, dining table, sleeping platform and stairs were all custom built of poplar.
The windows have aluminum frames, which were covered with poplar and stained with hemp oil to make them look nicer. The window sill was waterproofed with beeswax.
The doors to the bathroom and to the outdoors are both custom built of wood. The moist side of the doors (i.e. bathroom side and exterior side) are made of cedar, which is mold/rot resistant, while the rest is made of poplar. The doors were glued together with a less-toxic glue.
The shower was custom built of aluminum and stainless steel with a less-toxic adhesive (AFM Almighty Adhesive). This was the most difficult part of the project and took five months and lots of work to design, so it became costly. The reason she didnÕt choose the common types was to be sure it could withstand the flexing when the house was moved (i.e. no tiles), the need to save space and she wanted to avoid fiberglass.
The builder did not complete the interior work before the house was delivered. The bathroom, countertops and surface finish were done after the house was installed and with the owner living in the house. The windows were kept open and they used materials the owner tolerated well, even when wet. (Many people with MCS are not able to live inside while construction goes on.)
The appliances were purchased ahead of time and offgassed outside.
Choosing the materials
The purchased house plans specified the typical toxic building materials, so the owner had to research and test the materials herself. She tested every material used, which is especially critical here, since it is easy to stink up such a tiny airspace.
It was also a requirement that the materials could hold up to the vibrations and flexing of the whole structure when it is moved. It was also important to keep an eye on the weight of the materials, since there was a limit to how heavy the house could be.
There is a lot of wood in this house (floor, ceiling, kitchen cabinets, doors) so poplar was chosen as it is less aromatic than most types of wood. If the owner had to do it over again, she might use maple instead, since it is more durable and still less aromatic, though it is typically more costly.
Cedar is mold/rot resistant, but also very aromatic, so it could only be used on the outside.
The owner chose not to use steel doors and cabinets for aesthetic reasons. The available steel cabinets were also more expensive. Non-toxic wooden doors were not available, so they had to be custom built, using a glue the owner tolerated.
Space is at a premium in such a tiny house, which required some compromises. The most obvious space-saving feature is the sleeping loft and the integrated stairs up to it. She also chose not to have a washer and dryer.
The tiny bathroom required the installation of the smallest composting toilet available, and a custom-built shower stall.
The refrigerator is a small 3.1 cubic foot (88 liter) model that fits inside a cabinet. The stove is a reduced-size model.
Other space-saving features include the fold-down dining table under the living room window.
The kitchen cabinets had to be custom built, both because of the healthier materials and to fit the tight spaces.
There is not much room for storage. The owner does not have a lot of stuff, though she keeps some things in plastic bins under the house and in her car.
The house has no storage tank for fresh water. Pressurized fresh water must be supplied through a hose from the outside.
The house was built with holding tanks for graywater and blackwater, but they have never been used.
The toilet is a composting model from SunMar, which does not generate any blackwater. It has a vent stack to evaporate liquids and remove odors, but it has had problems with odors and overflowing liquids. The toilet requires a lot of unpleasant maintenance and has not been a success — the owner does not recommend it.
Wastewater from the kitchen sink, bathroom sink and shower is directed to an outside graywater system. Wastewater from kitchen sinks is considered blackwater in some jurisdictions, because it may contain bacteria from meats.
Heating, cooling and dehumidifying
The house is more difficult to keep heated and cooled than a regular house, since it has:
á less insulation
á open space below the floor (extra heat loss)
á lightweight construction (low thermal mass)
The small inside airspace also means that humidity builds up easily from cooking, showering and breathing. High humidity may be uncomfortable and cause condensation.
The house is located in a coastal climate, where summer days can be hot and humid (30¼ C / 86¼ F) while the winters can be as cold as -10¼ C (14¼ F). A mini-split heat pump provides heating and cooling for the house. The unit is in use every day of the year, to keep the house warm and comfortable.
The outdoor part of the heat pump is located in a utility closet, where it receives outside air through large vents on three sides. The indoor unit hangs over the door to the bathroom, so the air is directed into the main room.
The heat pump is rated at 12,000 BTU, which is a larger model than recommended for such a small space. A smaller heat pump would not have been adequate as the owner sometimes has to supplement with portable electric heaters. One heater warms the bathroom, which otherwise gets very cold. The main room sometimes needs one or two electric heaters, when it gets really cold outside.
The house has two exhaust fans to ventilate humid air from their sources. One is above the stove, while the other is above the shower.
The utility closet
The utility closet is placed on the front wall of the house, over the tongue of the trailer (see picture on first page). It contains the electrical breaker boxes, water heater, water cut-off valves and the outdoor part of the heat pump.
The water heater has a 40 liter (10 gallon) water tank, which is adequate. An on-demand water heater may be smaller, but they freeze easily and cannot be used in an unheated space.
Avoiding electromagnetic radiation (EMR/EMF) was not a major priority, but the owner included several simple design features that reduce the radiation levels — especially for the sleeping area.
The utility closet is mounted on the front of the trailer — furthest away from the bed. The underground electrical line continues on from there and does not run under or along the house.
The utility closet has two breaker panels. One panel is for loads that need power all the time, such as the heat pump, water heater, refrigerator and composting toilet fan. The second panel is for loads that can be disconnected at night, such as stove, lights and outlets. This second panel can be turned off by a master switch.
The house is wired with Ethernet cables, so there is no need to use wireless. The Internet modem is located in the utility closet with the Wi-Fi feature turned off.
The electrical wiring in the walls is encased in flexible steel conduits (MC wiring), which reduces the electric and magnetic fields around the wires.
The indoor part of the heat pump is placed as far away from the bed as possible.
Every appliance in this house is electric, so it is not realistic to make the house truly low-EMF, but a lot has been accomplished with simple design.
Transporting the house
The house was built at a shop and then transported to the present site. It took two hours on the road, which went without any cracking or other damage to the house.
The house is built so it can be moved again, if the owner needs to relocate later on. It just takes a truck suitable to pull a five-ton trailer.
The house site had no services available, so electricity, telephone/network, water and waste disposal had to be installed before the house arrived.
The electricity comes from an existing house on the property. They simply added an extra breaker and installed a 100 meter (300 ft) underground cable out to the new house, which has its own submeter.
The electrical company was not involved in the installation and was not notified. They simply continue to read their own meter and bill the owner of the property for all the electricity. The owner of the tiny house then pays the property owner based on what her submeter shows.
Internet service is provided by a cable company. They extended their coaxial cable from the house for free, though they did not dig the trench, which the owner had to organize and pay for.
The water comes through a long garden hose, which is not buried. The hose is protected from freezing with electrical heat tape and insulation. This has worked even at -10¼ C (14¼ F).
A small graywater disposal pit was dug next to the house to receive water from the two sinks and the shower. The pit is 1 ft x 4 ft (30 x 130 cm) and quickly became overgrown with lush vegetation. The owner has to remove sludge from the pit a few times a year, but it otherwise works well.
Most jurisdictions do not allow such a system. Some outlaw graywater systems entirely, some require a below-ground rock bin and some require wastewater from a kitchen sink to be disposed of as blackwater. It may be possible to bend the rules in some rural areas, where code enforcement may be very relaxed, as long as the neighbors do not complain.
The entire house cost CAN$ 75,000 (US$ 60,000 or 53,000 euros), which is about twice the cost of a conventionally built tiny house. Using healthy materials increased the cost greatly.
It is unlikely that this house can be built much cheaper, unless the owner does all the work. For cost comparison, a house of the same size and built with less-toxic materials is offered by Tiny Green Cabins in the United States for US$ 65,000.
This is less than the cost of a regular house, but the cost is high relative to the space:
US$ 375 per sq ft
CAN$ 469 per sq ft
CAN$ 4518 per m2
A regular house is better value for the money, but that doesnÕt help if the owner canÕt afford it, or needs the ability to move the house later.
The house is legally registered as a self-built travel trailer (self-built caravan). The Canadian Province had a checklist of requirements and the house had to be inspected before the papers and a license plate were issued. The registration was necessary to transport the house and to get it insured.
Many ordinances do not allow people to live permanently in a travel trailer, so a mobile home registration may be better. Registering the house as a mobile home was not possible as the requirements were too steep. One of the requirements was that the trailer had to be built in a certified mobile home facility, and such a certification is difficult to obtain.
The owner and the builder spent about a month sourcing the materials before construction started. Construction in the shop took five months before the house was towed to the house site.
A lot of interior work was still needed, though the owner moved into the house as soon as it arrived. She kept the windows open while the rest of the work was completed over a few months.
Some people with MCS would not be able to live inside until the house was finished, and might also need the wood terpenes to offgas for many months (perhaps even years).
The owner moved into her new house in October 2013, and has lived there for nearly 1½ years as of this writing.
She reports that she initially got more sensitive to various chemicals, but after awhile she started feeling much better than she had in years. In her own words:
I went from bedbound and in constant suffering to able to cook, clean, do errands, exercise and attend social events.
She is generally very satisfied with the house. There have been a few problems, such as cracking of the joint compound the first winter and she really misses having a washing machine. The composting toilet is the only major complaint.
She is happy with the size and layout of her living space. In the early days, when she still had to stay in bed a lot, she really liked having a window next to her bed.
If she could do it over again, she would design the bathroom for standard shower enclosures, leave out the graywater and blackwater tanks and make room for a washer/dryer.
The owner of this house has a blog, which provides more pictures and details of the project. It is available at: http://mychemicalfreehouse.blogspot.ca
Other articles about temporary and portable MCS/EHS housing are available at: www.eiwellspring.org/temporaryhousing.html