However, like any insulation, it’s essential to understand the potential problems that may arise. Not flammable, but it must be protected with wallboard.Radiant barrier insulation is a fantastic way to improve your home’s thermal insulation and keep your attic space comfortable. Not recommended for exterior, below-grade applications. Its closed-cell structure stops water vapor, and the foil-covered face acts as a radiant barrier. Good for: New construction, or retrofit in attics or crawl spaces R-value per inch: 4 No vapor barrier needed Foil-faced polyisocyanurate Although not flammable, must be protected from fire with drywall or plaster. Good for: New construction, attics R-value per inch: 4 Vapor barrier needed Low-density polyurethane spray foamīlocks the movement of air (eliminating the need for a vapor barrier), absorbs sound like a sponge, and flexes with the seasonal movement of the framing. Blown into place wet, it’s trimmed flush with the studs after it dries the trimmings are recycled. Spun from blast-furnace slag, this inorganic insulation does not burn or support the growth of mold or mildew. Good for: Masonry basement walls R-value per inch: 7 No Vapor barrier needed Mineral wool While not flammable, it must be protected with drywall or plaster to stop off-gassing during a fire. The rigid, closed-cell structure makes it impermeable to water. Good for: New construction, attics R-value per inch: 3-4 Vapor barrier needed: High-density polyurethane spray foam The sample shown is held together with a nontoxic acrylic binder instead of the typical formaldehyde-based binder. Lightweight batts of spun glass offer a predictable R-value if not compressed, but the fibers offer little resistance to air movement and convective heat loss. R-value per inch: 3.8 No vapor barrier needed if packed to a density of at least 2.6 lb./cu. Good for: Retrofit work, attic insulation. An adhesive reduces its tendency to settle. Made from pulverized newspapers and treated with boron to resist fire and pests. Good for: In-ground foundation insulation, masonry structures R-value per inch: 5 No vapor barrier needed Cellulose Flammable and must be protected from fire with drywall or plaster. Must be protected from solvents and sunlight. Its closed-cell structure stops water and water vapor, resists compression, and holds its R-value over time. Good for: Attic insulation, new construction, or retrofit work R-value per inch: 4 Vapor barrier needed: Yes Extruded polystyrene (XPS) R-value declines by as much as 50 percent at temps below 0 degrees F. Good for: New construction, attics R-value per inch: 3.7 Vapor barrier needed Loose-fill fiberglassįluffy bits of spun glass that are noncombustible and can’t decay. No-itch batts of recycled denim from jeans factories are treated with borates to resist fire and insects. Weigh your choices based on all the factors, including the abilities of the installer and the long-term energy savings. There are all kinds of materials to stuff in, nail on, spray on, or blow into walls and ceilings to lower your heating and cooling bills. But if it does, the barrier should face inside in northern, heating climates, and outside in humid southern climates. Not every type of insulation needs a vapor barrier. Vapor barriers-sheets of plastic or kraft paper-keep water vapor out of the wall cavity, so the insulation stays dry.
“It will sit there like a sponge, leading to mold problems and rot,” says Tom. Once insulation gets wet, it’s hard to dry it out.
To see if it makes economic sense to put a radiant barrier in your house, visit the Department of Energy’s Website ( Vapor blockers While radiant barriers are a boon in warm climates, they’re less useful in cold-weather regions because they prevent beneficial solar heat gain in winter.
Tests show that a radiant barrier in an insulated attic can lower attic temperatures by as much as 30 degrees. To be effective, the barrier’s reflective surface must always face an air space at least an inch thick and be installed shiny side up if laid on the attic floor, shiny side down if attached to the rafters. These thin sheets of shiny aluminum bonded to foam board, bubble wrap, or sheathing are often installed in attics to block heat from the summer sun. Not technically insulation, radiant barriers keep houses cool by reflecting thermal radiation.
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