Solar & Non-Toxic, "An Environmental Partnership"

The Detroit House: Construction Notes

The owner wants a house that is clear of toxic construction materials, and that uses solar power as much as possible. Together, we designed a compact eco-house that is affordable and yet viable well into the 21st century (and beyond).

The floorplan integrates the greenhouse with the living area. The kitchen is prominent, and faces the garden area outside. The stair leads to two additional bedrooms and a bath via an upper balcony.

From the road, you'll see this side. In addition there will be solar collectors in the yard. There are several innovations with this design. Stay tuned.

The footers are dug
Footers were dug in early December. We were scheduled to pour concrete on the 16th, but arrived at the job and found the trenches flooded from a faulty water meter. We drained them and struggled through weeks of bad weather. We finally caught a dry day and poured concrete on the 28th of December.

Foundation walls
Some lovely January weather helped to move the project along. The walls will be capped with a poured concrete bond beam. Then we will fill the floor area level with dirt, and prepare it for a slab floor with heat pipes imbedded in the concrete. Under slab insulation will be borax impregnated styrofoam.

Garden Terraces
The house and garden were designed together as a system. These garden bench cuts form a horseshoe in front of the house, where they can be seen from the kitchen. The greywater system will pump household wash water to the beds. The garden landscape is designed and constructed by Permaculturists Peter Bane and Keith Johnson.

The bond beam
A bond beam is a formed concrete top to a block wall. It serves to strengthen and tie together the blocks. It also pours down into the hollow block cores for more vertical strenth. In this detail, the bond beam was formed 4" wide. A strip of 2" insulation will be installed inside the beam, between the beam and the concrete floor slab. This allows the 6" wall above to cover the insulation edge.

Slab prep
At this point, the bond beam has been poured around the perimeter, the outer walls have been insulated, the interior has been filled to level, and slab prep is underway. Radon vents (the black snaking pipe) will draw gasses from under the slab and vent them away. Plumbing piping is separated into greywater from sinks/tubs/laundry, and blackwater from toilets. Water lines for heating the slab are installed alongside lines for domestic hot water.

Solar piping
Under the slab, the hot water pipes enter from an outbuilding that houses a solar heater with gas backup. The pipes get standard insulation plus the extra 2" styro channel. One set of pipes is for in-floor heating, the other is for domestic hot water.

Ready to pour concrete
Bring on the concrete. After the pipes and gravel, 2" insulation wraps the underside of the slab. Heat pipes were laid on a grid of #3 rebar on 2' centers. The bedroom, living areas, and greenhouse are on separate zones for better heat control.

Slab prep in the greenhouse
The greenhouse will be a heat source for much of the year. The slab is 6" thick here (4" elsewhere) for more thermal mass to avoid overheating. It's unlikely that the greenhouse will need much heat, but pipes are coiled through the floor for those coldest days in winter. Note the bond beam detail. The 4" wide bond beam will carry the weight of the house; a 6" wall will sits on top, covering the 4" bond beam and the 2" perimeter insulation.

Greywater Tank
3-way Bull Valve
Greywater enters this 30 gallon tank and is pumped to the gardens. A tie in with the regular sewer line makes this legal. The 4" line at the lower edge of the photo is the sewer line. The first tee in line connects to a drain/overflow. The next tee in the 4" line connects to a bypass line and a 3-way "bull run" diverter valve. The whole system can be bypassed for any reason by turning the valve. The valve itself is displayed by Jim, the chief plumber.

The slab is finished
Finally, the slab is finished. Next is brickwork, bringing the brick up to the level of the slab. A termite shield will span the gaps between the brick and the slab. Then framing will begin.

The framing went quickly. 2x6 stud walls and posts hold up the 2x12 rafters and beams. Floor and roof sheathing is 1x8 boards, the way roofs were built before plywood. The corners are braced with 1x4's let-in for structural rigidity. This photo was shot as we were about to sheathe the front roof sections.

Starting to look like a house
The wall sheathing is gypsum, a product more commonly used as a stucco base. We had some trouble getting ordinary gypsum sheathing due to an industrywide shortage, but this yellow fibreglass reinforced gypsum was in stock. It's very annoying to work with because of the fibreglass, but does a good job. The windows were installed the next day. They are made by Malta; casements and awnings, aluminum clad wood frame, double pane with low-E coating and argon.

Add the greenhouse
The greenhouse completes the framework, and the metal roof is on. The greenhouse rafters are 4x8 cedar. The overhead glass is double pane, tempered glass on the top layer for strength, laminated glass on the lower layer for safety, and low-e. The glazing system is by Pro-Seal. In the photo we have covered the top with plastic to keep out water until the glazing work is completed. Operable Malta windows are on the vertical face of the greenhouse.

Electromagnetic shielded wiring
Concerned about the negative effects of electromagnetic fields, we wired the house with some safeguards. The wire used is steel clad MC cable to ground the fields around wires. Also, most of the appliances are located in one corner of the house, the utility room and back wall of the kitchen. Other areas have been left clear and wired in a way that allows required circuits to be disconnected. And in bedrooms and kitchen, lights and plugs are double switched, so that both wires leading to the plugs and fixtures are disconnected when switched off.

Cellulose insulation in the ceiling
Insulation is a tricky job with Solar/Non-Toxic houses. It is essential for solar technologies to work, but most insulation available is toxic with formaldehyde. We chose to use cellulose for it's natural and renewable composition. We chose a brand that uses recycled newspaper for it's ecological contribution. It's dusty to work with, so it requires care and consideration for workers. As shown, in the ceiling cavities a fabric is stretched across the rafters. Then a pressure hose is inserted into a slit to pump in cellulose. To ensure venting, a cardboard baffle was inserted first against the underside of the roof decking.

Brickwork is complete
The brickwork was time and labor intensive, but will save maintenance in the long run. Very little painting will be needed outside, and the masonry gives a feeling of solidity and stability. In the children's morality play "The Three Little Pigs", brickwork is presented as a symbol of wisdom, maturity, and foresight. There will be no worries about wolves here, but brickwork is well known to protect against inside drafts in a strong wind.

Fibercement siding
The remaining areas are being covered in fiber-cement siding boards. The area above and around the greenhouse, as well as fascia boards and porch sides, are handsomely clad with this recycled wood fiber product. It looks like wood siding, but is more durable.

Finished exterior
The house is finished outside. The fiber-cement boards were colored with a natural stain made by Livos. The solar heat and photovoltaic panels are functioning. It's winter time and snowing, so the backup gas heater will kick in. The high today (December 30) is 21 degrees. The radiant floor heating keeps Steve warm. In fact, he turns the heat off for days at a time. (He just turned it on an hour ago)

Wheatgrass growing indoors
Steve is growing wheatgrass indoors for the winter. When the sun shines, he opens the french doors to the house, and heat floods in. At night and on cloudy days, he closes the doors. We installed a heating coil in the greenhouse slab, but Steve hasn't needed to use it.

Inverter and power control center
Photovoltaics panels supply direct current (DC) power to the battery bank. This inverter and power control center convert the DC power into alternating current (AC). The utility grid is AC, so the house has been designed to run on either the grid or on homemade AC from this equipment.

Hot water storage tanks
Sunshine heats a 300 gallon tank (behind an insulated partition) which supplies these auxiliary tanks. One tank keeps an ordinary hot water tank in the house warm, while the other supplies the in-floor heating coils imbedded in the slab.

More photos coming
Photos of the site will be posted as construction progresses.

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