We poured the foundation for the Passive House we are working on. Work on this house is much different than other homes we have worked on. As you may have seen in the earlier posts, the house sits on 8″ of extruded foam. To accomplish this we used layers of foam, layers of sand, etc so that we ended up with a basement floor that has integral perimeter footings. In this photo you can see the workers have placed concrete in about half the basement floor and are setting level lines for the interior of the floor. The perimeter of the floor is 15″ thick concrete, thinning down to 5″ thick floor area. Once the floor was cured we started in on the perimeter foundation walls. As with the majority of our homes, the foundation walls are being constructed using Reward Insulated Concrete forms. I really like these forms as they are easy to work with, have good carrying spots for horizontal reinforcing, and have very solid fastening systems for interior finishes. The workers start off by setting up lines and getting the walls excactly where they are supposed to be, then slowly building them up higher. Concrete is pumped into the forms and allowed to cure. McGhie & Betts in Northfield is doing our materials testing on the job.
Once the foundation wall was poured we moved on to applying 7″ of extruded foam insulation to the exterior of the foundation forms. This is where the Passive House work starts. We folded the plastic membrane from under the concrete floor up the wall and adhered it to the foundation wall. Once that was done the workers troweled adhesive onto the foundation forms and placed 7″ thick sheets of insulation into the adhesive, bonding the 7″ of foam to the foundation wall. Then, once the 7″ foam layer is in place workers apply a special “brown coat” of stucco material to protect and waterproof the foam. Lots of work, but the end result should be a house that is the easiest to heat for hundreds of miles….using almost no fuel.