There are many paths to reach a high performance home, and I want to take a look at two wall systems that are gaining in popularity.
Double Stud Wall
As the name implies, this wall system consists of an inner wall that provides framing for attaching gypsum board and an outer wall that does the same for sheathing, rigid foam insulation, and siding. Two 2x4 framed walls spaced five inches apart provide a wall cavity more than 11 inches deep. The goal is to eliminate thermal bridging, and the spacing and blown-in insulation keeps the studs in one wall from touching the studs in the other wall.
Insulated Concrete Form Wall
Insulated concrete form (ICF) construction combines concrete and rigid foam for walls that are thick, sturdy, and continuously insulated. Studies comparing ICFs with stick-frame construction have shown that in otherwise identical homes, the ICF houses had a 9% better whole-wall R-value and were 10% more airtight. ICF walls have almost no thermal bridging in the wall itself and, with proper design details, thermal bridging can be almost eliminated at the rim joist as well.
Foam blocks are typically comprised of two 2-inch-thick, 16 by 48-inch rectangles of foam that are connected by plastic, metal, or foam ties. The ties hold the foam panels 6 or 8 inches apart during the pour and remain in place afterward. The blocks are stacked like bricks to create the wall forms for the concrete. Steel rebar is added to the cavities for additional strength.
When properly constructed and all the details are in place, double-stud walls provide a high level of air sealing and insulation value, as well as a comfortable, quiet home. But keep in mind the level of detail from two framed walls, insulation, air sealing, multiple exterior layers for vapor and air control, and door and window flashing must all be done well to deliver the expected performance.
By contrast, ICFs deliver the wall system, continuous insulation and air sealing all in one operation.
When you consider the total cost of labor and materials, ICF walls are very price competitive for installation, and will usually deliver a lower total cost of ownership over the life of the building.
This blog was developed by Fox Blocks. All posts, sponsored and un-sponsored have been reviewed and approved by the Sustainable Community Media Editorial Team to ensure quality, relevance/usefulness and objectivity.
/ A Detroit native, David T. Morris, LEED® Green Associate, used his drive for entrepreneurship, innovation & new product development to develop a patented product and later took a new building product to market. In 2012, he became U.S. East Regional Manager with Fox Blocks, a division of Airlite Plastics Company, managing ICF sales in seven states. Since 2006, David has delivered more than 140 IFA/ICF training seminars to contractors, plus another 120 presentations to architects and engineers. He is a featured speaker and SME on High-Performance Buildings, and his efforts have resulted in environmentally friendly construction being specified for residential, commercial, and institutional buildings throughout the country.