Proper insulation is key to energy-efficient and cost-effective homes. It makes buildings resistant to drafts and reduces the size of the mechanical systems needed for heating and cooling. By reducing moisture infiltration (which can create condensation within the walls), insulation also preserves building materials. Today’s diverse marketplace offers many outstanding insulation products. Prefabricated, insulated wall sections are another option.
Batts and rolls
For decades, the most common insulation has been fiberglass, made from partially recycled glass, sand and manmade binders. Typically available in uncut rolls and batts (precut strips), it’s widely available, requires little skill to install, has a very low upfront cost and is often the most practical choice for small remodeling and DIY projects.
Fiberglass is energy-intensive to produce, and it’s easy to inadvertently leave gaps when installing it. It can also be a skin and respiratory irritant, although the International Agency for Research on Cancer recently cleared fiberglass of its status as a possible human carcinogen.
Knauf Insulation recently introduced petroleum-free EcoBatt fiberglass that contains no phenols, formaldehyde, acrylics or artificial colors. Johns Manville makes a complete line of fiberglass insulation products with a formaldehyde-free binder.
Building codes may require a vapor barrier over fiberglass insulation. However, when outside temperatures are warm and humid and conditioned indoor air is cool, moisture can become trapped inside exterior walls on the surface of impenetrable vapor barriers. An alternative is "unfaced" fiberglass insulation (without a vapor barrier) or products that use facing such as coated kraft paper or foil. CertainTeed’s MemBrain vapor barrier changes its permeability depending on the ambient humidity, so moisture can dissipate easily.
Dow’s fiberglass alternative, Safetouch, is made from polyester and has no borates, acrylics or formaldehyde. Bonded Logic’s UltraTouch batt insulation is a formaldehyde-free alternative to fiberglass and polyester made from recycled, post-industrial denim and cotton. Good Shepherd Wool’s all-wool batts are naturally flame-resistant and effectively absorb sounds and odors.
Spray- and blown-in insulation
Cellulose, foam and fiberglass insulation can be blown or sprayed into wall cavities, a process usually done by professionals.
Cellulose, typically comprised of recycled newsprint, is efficient, innocuous and has low embodied energy. It can be blown into existing walls in a dry form or dampened and sprayed into stud and other cavities. Cellulose can fill cavities more completely than fiberglass, creating the tightest building envelope. It also creates a more effective air barrier, eliminating the need for a moisture barrier.
Some spray foams use ozone-depleting propellants (HCFCs), although this is changing rapidly. Some can produce toxic gases during a fire. On the upside, they also typically have the highest R-value of any insulation. Air Krete, made from air, water and cement, does not burn, uses no harmful propellants and is nontoxic. Icynene’s new LD-R-50 insulation is free from harmful propellants and flame retardants.
During remodeling projects, you can add insulation to a wall’s interior or exterior. Dow’s Styrofoam brand insulation, available in 4-by-8-foot sheets in thicknesses as thin as 1⁄2 and 1 inch, can be applied over exterior sheathing. SayrCo’s new lightweight WEKA panels—which use lamb’s wool with calcium oxide and a nontoxic binder to replace the gypsum in traditional wallboard—comes in 2-by-8-foot and 4-by-8-foot sheets that can be installed inside the home.
DON’T choose insulation based solely on the installed price.
DO ensure that your home’s insulation meets or exceeds local codes.
Michael Fallarino is a building contractor and journalist.