The attic was originally insulated with a double layer of straw bales sitting uncovered on the attic floor. This worked OK the first winter, but during the second winter mice, as well as wind from under the eaves (we have a “cold” roof), began to disassemble the bales. By the third winter, some of the straw had broken down so much that it ceased to function as a good insulator; in addition, we discovered that David had developed a straw dust allergy.
In the summer of 1999 we converted part of the attic into office space for the business that we run from home and replaced the straw with blown-in cellulose insulation. We’ve been quite happy with the results. Our attic office is surprisingly comfortable even on hot summer days and in the winter we are always warm.
The basement ceiling was insulated with recycled cotton batts stuffed between the floor joists of the first floor. However, we had trouble insulating the space between the stone foundation and the straw bale walls, since we could not perfectly fit the rectangular cotton bats into the irregularly shaped space between the stones and the straw bale wall. We later added a layer of blown-in cellulose, which has solved the problem of the air infiltration around the perimeter.
Cellulose insulation also surrounds the cold water pipes that come up from the unheated basement, and the area around the windows is insulated with spray-in polyurethane foam (see Windows).
In the new building, we have used pink foam board below grade and straw bales for the walls. We used blown in cellulose for the ceiling, the basement ceiling and walls, and anywhere else that straw was not ideal. The ability of blown in cellulose to fill odd shaped cavities makes it great and while it does need to be installed by a professional installer, it is a fast and relatively easy process. And, of course, the cellulose is made from recycled paper!