Many types of insulation are available to insulate homes. To choose the best type of insulation, should first determine where the insulation needs to be installed and the recommended R-values for areas to be insulated. The maximum thermal performance or R-value of insulation is very dependent on proper installation.
Blanket insulation is the most common and widely available type of insulation. It comes in the form of batts or rolls. It consists of flexible fibers, most commonly fiberglass. Batts and rolls are also made from mineral (rock and slag) wool, plastic fibers, and natural fibers, such as cotton and sheep’s wool.
Fiberglass Batt Insulation
Batts and rolls are available in widths suited to standard spacing of wall studs, attic trusses or rafters, and floor joists. Continuous rolls can be hand-cut and trimmed to fit. They are available with or without facings. Manufacturers often attach a facing (such as kraft paper, foil-kraft paper, or vinyl) to act as a vapor barrier and/or air barrier. Batts with a special flame-resistant facing are available in various widths for basement walls and other places where the insulation will be left exposed. A facing also helps facilitate fastening during installation. However, unfaced batts are a better choice when adding insulation over existing insulation.
Unlike most common insulation systems, which resist conductive and sometimes convective heat flow, radiant barriers and reflective insulation work by reflecting radiant heat away from the living space. Radiant barriers are installed in homes — usually in attics — primarily to reduce summer heat gain, which helps lower cooling costs. Reflective insulation incorporates radiant barriers — typically highly reflective aluminum foils — into insulation systems that can include a variety of backings, such as kraft paper, plastic film, polyethylene bubbles, or cardboard, as well as thermal insulation materials.
Radiant barriers are more effective in hot climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can lower cooling costs 5% to 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it’s usually more cost-effective to install more thermal insulation.
Liquid Foam Insulation
Liquid foam insulation materials can be sprayed, foamed-in-place, injected, or poured. Some installations can have twice the R-value per inch of traditional batt insulation, and can fill even the smallest cavities, creating an effective air barrier. Today, most foam materials use foaming agents that don’t use chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful to the earth’s ozone layer. Available liquid foam insulation materials include cementitious, phenolic, polyisocyanurate (polyiso), and polyurethane.
Installation of most types of liquid foam insulation requires special equipment and certification and should be done by experienced installers.