Photo credit: erik-mclean
MATERIALS THERMAL & MOISTURE BUILDING INSULATION
In building construction, various forms of insulation are included as a means of reducing the transmission of thermal energy through walls, ceilings, and floors. In simple terms, this helps keep heated interior space warmer in the winter, and air-conditioned spaces cooler in the summer. Reducing the transmission of thermal energy not only makes spaces more comfortable, but it is also essential to controlling energy costs. All building materials have an inherent insulating property, usually measured on a scale known as R-value, but additional materials are integrated into the building construction specifically to add insulating value to the walls, floors, and ceilings. Historically, many different materials have been used as insulation, and many of these have now been abandoned in favor of more modern and efficient materials. The type of insulation you select when designing and constructing a space will depend on your climate and the R-value you seek.
Blanket and Batt Insulation By far the most common type of insulation consists of a “blanket” of rolls or batts of insulation used to fill the cavities between framing members in walls, ceilings, and floors. Batts can also be laid in a blanket across attic floors in to insulate the spaces below. Batts and rolls consist of flexible fibers woven together in strips of varying widths and thicknesses for different applications. Most commonly, batt 17
insulation uses fiberglass fibers, but it can also be made using mineral fibers, plastic fibers, or natural fibers such as wool or cotton. Blanket insulation can offer R-values ranging from R-11 (for 3.5-inchthick batts) to 38 (for 12-inch-thick batts). Batt insulation is one of the most inexpensive forms of insulation, and one of the easiest to install.
Foam Board Insulation Polystyrene or polyurethane foam boards provide superior insulating R-values for relatively little thickness. They can be used for nearly any part of a building and are especially effective for insulating exterior wall sheathing, interior sheathing for basement walls, and in special applications such as attic hatches or air gaps where floor joists meet foundations. They offer a good way to insulate the spaces between roof rafters in unvented attics. When used on interior wall applications, foam panels must be covered with half-inch-thick gypsum board panels or another approved building material. Foam board provides excellent thermal resistance, as much as twice that for other materials of the same thickness. They can easily be trimmed to size for various applications.
