leangreen.org recycled renovation on a low-budget ration

Between the silicone caulk, soy-based spray foam, and recycled denim insulation, we’re insulating at about $1 per square foot. Here’s how we approach each wall cavity:

1. Use GreatStuff’s fire-blocking foam (and all its chemical warfare) to fill and surround all penetrations between floors, as required by code.
2. Use SoySeal’s Greenguard-certified spray foam along cavity perimeter and 1/2-inch to 1/4-inch gaps where it’d be difficult to work the cotton insulation.
3. Use Silicone II clear caulk along the seam between the concrete perimeter foundation wall and the sill plate and any gaps less than 1/4-inch.
4. Use a sharp blade pocket-knife and 2×4 straight edge to cut the R21 UltraTouch Cotton batt insulation to fill the 6-inch cavity. Use the knife and some arm wrestling to tear apart the batts to fit around obstacles. Although not as physically easy as fiberglass, the batts are workable with bare hands. They do release a borate dust as your tear, so we wear masks.

We ordered the SoySeal from Home Depot’s online service, 6-pack for $30. They’re only 16-ounce cans and you go through them quickly, about one per 100 square feet of wall space, so the packaging generates a lot of waste. We ran out so we used the regular GreatStuff (available at the actual Home Depot for about $4/can) and unlike the SoySeal, we immediately could smell the off-gas of chemicals that seemed not-so-friendly to the respiratory system and brain function.

So we’re trying to combine the best of both worlds at a compromise price: spray foam airtight seal and removable, high R-value, sound-dampening batts. Costs are running about half of open-cell spray foam ($2/sf) and double the fiberglass batt cost (50 cents/sf). As for time, we’re running over an hour per 100 square feet just for the caulk and foam. We’re just at the test-run stage, so critique of our technique is welcome.