Recent advancements in insulation technology provide architects, engineers and contractors with options formerly unavailable. Besides controlling heat loss, factors gaining importance as insulations become specialized include impact resistance, fire resistance, acoustical control, dimensional stability and resistance to settling. Also important are the insulation's component compatibility, attachment capabilities, installation speed and the maintenance required. An assortment of insulation types is available to fit every construction need, and care must be taken when choosing the best one for the job.
By far, the most common forms are rigid boards and batts, made of a variety of materials: mineral fiber, which uses a glass mat facer and has a relatively high R-value; perlite, formed by combining volcanic minerals with indigenous organic fibers; polyisocyanurate, a closed-cell insulation manufactured through a chemical reaction for a high R-value; glass fiber such as Schuller's Thermal-Shield - highly stable and compatible with bitumens and other adhesives, but less resistant to moisture than cellular glass - wood fiberboard, formed of wood or cane fibers combined with a variety of binders; and expanded and extruded polystyrene, both made of closed-cell foam. The latter, such as T. Clear's Lightguard or Dow Chemical's Deckmate-Plus, is the only insulation type usable with protected membrane roofs (PMRs), which diminish the susceptibility of the membrane to the sun, weather and thermal cycling.
Composites of two insulation types take advantage of the properties of each, such as Thermasote, a product made by laminating homasote and polyisocyanurate. Polyurethane foam (PUF) or spray-applied cellulose are high-R-value alternatives that can be tube-sprayed in new construction or added to existing insulations. Aluma Shield's insulated metal paneling is a durable and easily installed roofing system-and-insulator in one.
Solar reflectance is an important property of every insulation. According to Paul Berdahl, a materials specialist at Lawrence Berkeley National Laboratory in California, roofs with a high reflectance can save 40 percent on HVAC costs. 'Anywhere air-conditioning bills are significant, I would look at a light-colored roof,' says Berdahl. Increased awareness about the role of radiation in heat loss may be behind the current trend toward radiant barrier systems, which combine high reflectance with installation versatility. Radiant barrier products are also good choices for insulating ductwork and pipes. For other specialized insulating needs, Homasote's prefinished fabricboard and panels provide a solution for interior offices and walls.
Environmentalism is another big factor in specifying insulation. All Homasote products are produced from post-consumer wastepaper. Utilizing recycled content diverts materials from the waste stream and reduces materials mined from natural sources. Cellulose is the standout here, with recycled newsprint accounting for three-fourths of its content. A number of potential insulators are being tested by the Department of Energy, with the expectation that their use can promote sustainable development.
Insulation accounts for a small percentage of building cost versus the return in comfort and energy savings that can be realized. New technologies may be loading up the shelf with choices, but they are also increasing the size and speed of those returns.