Wednesday, May 12, 2010

ZEH, SIS, and other energy-friendly acronyms to know

The envelope of the house is rapidly developing, so its time to highlight a few key products. The house will have an exterior sheathing of a new product from Dow, Styrofoam SIS (Structural Insulated Sheathing). Winner of the 2009 Green Product Awards from Building Products Magazine, STYROFOAM SIS™ Structural Insulated Sheathing from Dow combines a structural layer, a moisture barrier, and foam insulation, providing R-values of 3.0 at ½ inch or 5.5 at 1 inch. Made of up to 80 percent post-consumer recycled content by weight, STYROFOAM SIS™ Brand Structural Insulated Sheathing is ENERGY STAR-qualified. And, at one-third the weight of OSB†, it is easier to handle and quicker to install. One judge summed up the products benefits as, "This appears to be an excellent product, providing wall bracing, energy performance, and the potential for weatherization all in one. The labor savings alone is huge." Our builder chose to use the 1/2 inch product, after an analysis revealed relatively little energy gain for the thicker product in our build (rule of diminishing returns). The panels are nailed or stapled in place to the outside of the studs and the seams are taped with WEATHERMATE™ Construction Tape (2-7/8" wide) .

WEATHERMATE Construction
Tape is pliable, ensuring a tight
seal, even at extremely low
temperatures. The oriented
polypropylene backing is
formulated with a UV-treated
film to help resist degradation
from exposure to sunlight.

The garage is not insulated, but covered with WEATHERMATE™ Plus – Housewrap to serve as an air and moisture barrier. It is significantly superior in water resistance, air porosity, vapor permeability and tear resistance than the more commonly used Tyvek. It also possesses prolonged UV ray resistance, allowing it to be exposed up to 120 days before significantly degrading (hopefully our garage will not test that limit).

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