One option for building a high-performance home in a cold-climate is to build with insulated concrete form blocks, known as ICF. Chris Anderson, of Anderson Custom Carpentry, is using Faswall blocks to build his own home south of Bozeman, Montana. These structural blocks are made from concrete and mineralized wood - essentially recycled wood shavings and a binder. The blocks are thermally efficient and fire-resistant, two critical factors for building in the Rocky Mountains. Because the texture is rough, there is a lot of friction between the stacked blocks, therefore helping to prevent a concrete blow-out during the pour.
Andrea Michael, Love | Schack’s project manager for this custom home, visited the building site during a tutorial and open house hosted by ION EcoBuilding in late August. Joseph Becker, ION Ecobuilding’s Western US representative, discussed window details, plaster prep, building science and air and vapor control. The group looked at the foundation and walls that are underway. One thing we love about this building system is the blocks form a perfect base for applying a finish of lime plaster, a great material to incorporate in an eco-friendly project. Like a really good frosting, the thicker the better, but even a thin layer of clay or lime plaster absorbs vapor and helps maintain a constant and comfortable humidity within a space. (Lime plaster is hygroscopic & anti-microbial!) Check out Limestrong to see one of our favorite plasters and Lindsey Love’s tutorial on plaster to learn more about how to make this paint alternative. Other substrates that work effectively in cold climates and are great for plaster are hemp + lime and strawbales.
In specifying sustainable building materials, Love | Schack works diligently to eliminate high carbon and toxic materials and finishes whenever and wherever possible. Faswall does include some concrete (which is very carbon-intensive) but allows us to avoid foam, which is also high in carbon and requires toxic blowing agents which can be harmful in production and installation. Plaster, layered over an inert substrate of mineralized wood and concrete, creates a non-toxic envelope with no off-gassing. Plaster over this type of substrate also creates an easy method of air sealing; unlike traditional framing where you have lots of gaps and holes to fill, this method of stacking blocks has very few seams, making it easier to create an airtight envelope.
We are excited to watch this home take shape!