Fibrous Insulations
Fiberglass
Manufacturers are now producing higher density fiberglass batt insulation in addition to traditional low-density batts. These new products do a better job insulating buildings with limited insulating space, as with cathedral ceilings. Medium density batts have twice the fiberglass while the high density batts have three times as much as standard insulation. Increasing density typically equates to a higher initial investment, but with greater energy savings over the long term.
Cotton Fiber
Cotton insulation is available in batts or as loose fill. It usually consists of a mélange of recycled cotton, polyester and nylon fibers. This mix is then treated with a flame retardant and insect and rodent repellent. It meets the same Class I standards for fire resistance as fiberglass insulation while matching R-values and durability. The batts are standardized much the same as traditional fiberglass insulation, but unlike fiberglass, do not irritate the skin.
Plastic Fiber
A newer type of insulation on the marketplace is plastic fiber insulation. Plastic fiber batts are made from recycled milk cartons and other PET plastics. The thick fibers make soft, non-irritating batt insulation that resembles very dense fiberglass. The recycled content and clean manufacturing processes help make this a good addition to the green market. While it does not irritate the skin or burn when exposed to an open flame, it will melt at a high enough temperature and can be difficult to cut with standard jobsite tools.
Natural Fibers
Many other materials are used for insulation around the world: most notably wool and hemp. Wool and hemp insulations are commercially available in the United States. These types of alternative products offer R-values similar to other fibrous products, though at a significantly higher cost. Their primary advantages are their sustainability and low impact on the environment.
Insulating Foams
Urethane Foam
There are a number of types of insulating urethane foams currently in use in construction. New closed-cell polyurethane foam insulation uses a non-chlorine blowing agent, which has not been shown to deplete atmospheric ozone. This increases the cost to around three times as much as traditional polyurethanes, however.
Low-Density Foam
Low density open-cell polyurethane foams are semi-flexible, cellular plastics. While most polyurethane insulations use ozone-depleting fluorocarbon blowing agents, low density varieties use water or carbon dioxide (CO2). Low-density urethanes may be sprayed into exposed cavities, as in new construction, or less commonly poured or pumped into a smaller opening. The foam is water vapor permeable, while remaining flexible, water repellent, and resistant to wicking.
Cementitious Foam
Magnesium silicate, cement-based insulation is pumped into closed cavities, and is made from material extracted from seawater. Its non-toxic attributes make it very popular with chemically sensitive individuals. Installation is done before applying any finish materials. It is not temperature sensitive, so can be installed indoors at any time of year, and is non-flammable. The consistency of the foam is similar to meringue, and when cured: to stiff pudding. It is very susceptible to water damage.
Rigid Panels
Composite Panels
Composite insulating panels include structural insulating panels (SIPs) and insulated roof panels. This type of insulating material consists of an insulating core panel that is sheathed on both sides. The insulation is usually a foam-based plastic such as polystyrene or isocyanurate. Sheathing materials vary, but usually include plywood, oriented strand board (OSB), or waferboard. Interior panels are also available with gypsum board sheathing.
Because of their inherent rigidity, composite panel systems reduce the need for structural lumber, eliminate many opportunities for air leaks, and shorten assembly times. Comparisons of traditional and composite panel test houses show a slight energy savings with structural panel construction. Their ability to deaden sound makes them excellent for use in interior walls.
Insulated roof panels are constructed similarly to SIPs, but with a nailable surface for applying roofing material on one side. These panels are very effective at increasing the insulating value of a roof and can help prevent condensation in attics. They are also available with built-in air channels for ventilated roof designs.
Straw Panels
Compressed-straw panels have been utilized in the construction of hundreds of thousands of buildings around the world since their development in the 1930s. Panels are usually 2 to 4 inches thick, use no adhesives, and are sheathed with heavy Kraft paper. These panels are effective at absorbing sound. A modified compressed-straw product is available as a structural insulated panel, as well.
Insulating Masonry Products
A variety of permanent, insulated concrete form systems are available. These systems typically involve pouring cement into a pre-built, insulated and reinforced form. These rigid foam board and/or stackable hollow-core foam blocks are left in place after the concrete has cured. The rigid board type consists of panels of foam separated by structural plastic. Building codes also require additional sheathing with an appropriate fire-resistant material.
Solid, pre-cast, autoclaved concrete masonry units have recently become available in the United States, and have been used in Europe since WWII. Air makes up 80% of the volume of the material, giving it ten times the insulating value of standard concrete. Blocks are large, light, and flat. This material is easily cut, fastened, and shaped with ordinary tools, but since the material readily absorbs water, it requires protection from moisture.