The Best Way to Insulate an Attic

Attics are one place where you can realize significant savings on energy costs by installing spray foam insulation. Infrared photos of most homes and buildings highlight the substantial amount of air leakage that takes place between the conditioned spaces and the unconditioned attic spaces.
If the existing insulation, whether it is blown-in or batt, has been in place for more than ten to fifteen years, it is most likely not delivering the R-value it did when it was installed. Both these types of insulation sag, compress and lose their insulating values over time.
If you want a permanent solution to a warm and cozy, or cool and comfortable, home, then you will want the gold standard in insulation which is spray foam. It will last as long as your home will last and provide structural strength at the same time.
Depending on where your building is located and whether you have duct work or air handlers in the attic will determine where spray foam will be applied. If there is no duct work or air handler units located in the attic, then spray foam between the rafters on the floor of the attic is usually done. In that case, closed cell spray foam is used which also effectively bars moisture from leaching from the attic as closed-cell foam also provides a moisture barrier. The rest of the attic can breathe through soffit or gable vents which is helpful for controlling mold and mildew growth. Another benefit, although it is not discussed that often, is that you can walk on closed cell foam after it cures completely which is a major plus if you are used to walking on roof joists or trusses across your attic.
If, however, you have an air handler or duct-work in your attic, a different pattern of spray foam insulation is typically prescribed. For best results and most efficiency, you will want to spray the floors, under the roof and the gable ends of the attic creating a completely sealed and conditioned envelope. Your air handler will intake and discharge air directly to the outside through proper venting for this method. The air handler, and all the duct work are now completely enclosed in conditioned space. In some parts of the country where there are no crawl spaces or basements and all the HVAC equipment is installed in attics, this can save substantial energy dollars in the hottest months – up to 50%. Further, the equipment doesn’t need to work as hard to deliver the correct temperature air through the duct work since both start out in conditioned air that is neither as hot as it is outside nor as cold as it gets in the winter months.
A proper installation of attic spray foam will include insulated electrical boxes for any recessed lights. Also, make sure that there is proper clearance around any gas vents.
Per inch of depth, spray foam delivers a higher R-value than any other type of insulation. It is a permanent upgrade for your home or business building and will last just as long without needing replacement. A great deal of air leakage comes from attics so this is one place you want to make sure is sealed up as tight as possible with spray foam.

Spray Foam for Unvented Attics