What Is It and How Does It Work?
Insulation provides resistance to heat flow in your home – preventing warm indoor air from leaving your home during the winter, and preventing hot outside air from entering your home during the summer. A well-insulated home will have lower heating and cooling bills. Because heat always flows from a warmer space into a cooler space, warm air flows into your house in the summer and flows out of your house in the winter. Insulation provides resistance to this heat flow all year round. The thermal resistance that insulation provides is measured by its R-value—the higher the R-value, the more effective the insulation will be, if properly installed.
What Are the Options?
Blanket Insulation
Blanket insulation consists of fiberglass, mineral (rock) wool, cellulose, or cotton fibers formed into batts or rolls of different lengths and widths. It is available unfaced (no covering) or sandwiched between paper, foil, or vinyl facings that act as an air or moisture barrier, or a fire retardant. It comes in widths to match standard distances between wall studs or ceiling and floor joists. It’s best in areas of regular, even size, rather than in small or irregularly shaped areas. It is usually pink, yellow, or white.
Learn More
Loose-fill Insulation
Loose-fill insulation consists of loose cellulose, fiberglass, or mineral (rock) wool fibers or pellets that is blown into a space with specialized pneumatic equipment. Fiberglass is typically yellow, pink, or white; cellulose and rock wool are typically gray or grayish white. In new construction, loose-fill insulation is used to fill small, irreguarly shaped, or hard to reach areas, or places where obstructions prevent blanket insulation from being used. In existing homes, it is used in unfinished attics and to fill wall cavities that contain little or no insulation.When blown-in cellulose is made sufficiently dense (a technique known as dense pack), it prevents settling and provides additional resistance to air infiltration and therefore has a higher R-value. Loose-fill insulation is sometimes mixed with a water-based adhesive and spray applied (sprayed in place) by specialized equipment. This “wet” application increases its density and allows it to stick in place, preventing settling. It must be allowed to dry before the wall cavity is closed up.
Learn More
Reflective Insulation
Reflective insulation is like other insulating materials that stop heat transfer through convection and conduction, but the radiant barrier layer also stops heat transfer via radiation. It is designed to block radiant transfer across open spaces, such as between a heat-radiating surface (like the roof) and a heat-absorbing surface (like fiberglass insulation).
A radiant barrier is a metallic foil, usually reflective aluminum, which is attached to some kind of backing—such as kraft paper, foam board, or plywood—and installed in an enclosed air space, such as on exterior wall sheathing or in an unfinished attic. Reflective insulation is typically made from thin sheets of plastic cells (like bubble packing) or other materials that impede conduction, with a radiant barrier layer on one or both sides.
Learn More
Rigid Insulation
Rigid insulation is made from plastic foam, typically polystyrene or polyisocyanurate, that is expanded or extruded into boards. They are thin (most commonly 1/2 to 2 inches thick), lightweight, strong, and a good thermal barrier. (Mineral fibers are also pressed into rigid insulation that can withstand high temperatures. This is most commonly molded into pipe and ductwork coverings.)
Rigid foam insulation can be used to insulate almost any part of the house, from the foundation to the roof. It is used in places with narrow cavities, such as foundation or basement walls, exterior walls under finishing materials, under concrete slabs, and in unvented low-slope roofs or cathedral ceilings. Foam boards are often faced with a material to act as a vapor barrier.
Learn More
Spray Foam Insulation
Spray foam insulation can be sprayed, injected, or poured into exterior wall cavities and perimeter joist spaces. The foam is typically polyurethane or isocyanurate mixed with a foaming agent. It forms to the shape of the space and then hardens, sealing it tightly. Many newer products, such as soy-based polyurethane foam, are environmentally friendly. Slow-curing foams expand slowly so they can flow over any obstacles, such as pipes, before hardening.
Learn More