from Todd in Muskego, WI:
#250
I am looking to build a new home. I am looking for cost comparisons and r-values for SIPS, ICF'S and spray foam and what is the best value for the money?
The best way is to compare costs is to get quotes.
The only reliable way to provide cost comparisons for different insulation systems is to get quotes from contractors who install those systems.
With regards to SIPS (Structural Insulated Panel Systems): These systems are prefabricated building panels consisting of plastic foam cores sandwiched between two skins (typically oriented strand board (OSB) or plywood). We normally see these using expanded polystyrene (EPS) as the core with an R-value of 22 or 24 depending upon the density of the EPS being used. These R-values are based on a 5½” thick core. R-values for 3½” core are in the 13 – 14 range.
ICF (Insulating Concrete Forms) are hollow building elements made of plastic foam that are assembled, often like building blocks, into the shape of a building’s exterior walls. The ICF’s are filled with reinforced concrete to create structural walls and are left in place to provide insulation and a surface for finishes. Insulation values of ICF walls vary depending on the material and its thickness. Typical insulation values range from R-17 to R-26, compared to between R-13 and R-19 for most wood-framed walls.
Your question regarding the use of spray foam has many implications because of the varying types of spray foams that are available. Spray foam insulation is usually defined by its density and its ability to be a vapor retarder. Denser foam has a greater R-value (5.5 to 6.5 per inch) compared to R-values ranging from R-3.6 to R-4.0 per inch for half-pound foam.
Besides using spray foam, other premium insulation systems are worthy of consideration in exterior wall cavities. Damp sprayed or dry packed cellulose and fiberglass (Blown in Blanket System) have been used in northern climates with much success in reducing air leakage and providing good thermal performance. Consider also, the use of rigid foam boards on the exterior to reduce thermal bridging at studs and other framing members.
One last thought, give consideration to engaging the services of a consultant partnering with the Focus on Energy New Homes Program who can provide up front computer modeling of your home to help you determine the best course of action based on your requirements, desires, and budget. This computer modeling can help determine operating costs of your home and can compare different insulating scenarios (and HVAC equipment) to help you make informed choices.
Published Wednesday, December 02, 2009