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Insulate the attic for maximum efficiency
- Gary Parsons
As America gears up for Halloween, the "spooky" places in our homes, like the attic, become areas that children fear because of scary stories that they hear and see on TV. For adults, the scary story lies in the fact that half of the air leakage in their home may be coming from the attic and that the energy (and money) they are using to regulate their indoor environment is not being used as efficiently as possible.
Like most spaces used for storage and other non-living areas, the attic often has overlooked 
spaces in which poor air sealing and insulation can lead to a decrease in whole-home energy efficiency and indoor comfort. To address energy loss stemming from the attic homeowners should add insulation where appropriate, and more importantly seal any gaps and cracks.
In recent retrofit test homes part of the U.S. Department of Energy's (DOE) Building America program, supervised by The Dow Chemical Company ("Dow") led Cost Effective Energy Retrofit Team, air sealing the attic reduced air leaks in the home by almost half. Remarkably, one component spray polyurethane foams like GREAT STUFF™ Insulating Foam Sealant from Dow, readily available at local hardware stores, were shown to work as effectively as professionally installed spray foams. If you're a DIY homeowner in need of a Saturday home improvement project, you can air seal like a pro without being one.
Now let's take a look at some easy ways that a DIYer or contractor can shore up the average attic to create a more energy efficient home.
Where walls join the attic
Air sealing the points at which exterior and interior walls meet the floor of the attic should be a high priority for homeowners looking to make energy efficient upgrades to the attic. For this application contractors can apply a quick cure polyurethane foam sealant such as FROTH-PAK™ Foam Sealant to fill any cavities that exist between the walls and the attic floor.
HVAC gaps
Check your attic for HVAC system and pipe penetrations, and gaps and cracks around these structures, because they can be paths through which unregulated air and moisture can pass through the building envelope. For these types of penetrations use quick-curing spray foam sealant or insulation to air seal around all of the HVAC boots where they penetrate the drywall into the living space below. Additionally, it's a good idea to seal where the flexible insulated ducts connect to the penetrating boot. Sealing these HVAC areas with air sealing products like FROTH-PAK™ Foam Sealant (pictured) or GREAT STUFF™ Insulating Foam Sealant helps to ensure that energy the homeowner is using to heat or cool their home is used efficiently.
Attic hatch door
The attic hatch door can be a large poorly air sealed and insulated opening in an otherwise tight building envelope. There are generally two types of attic hatch doors, those with pull-down stairs and those with a simple moveable piece of wood covering the opening.
Regardless of which type of hatch door the project features, air sealing around the opening is paramount because it is generally the weakest link in attic insulation. To help keep the conditioned air in the living space from escaping through the attic, homeowners can seal the gap between the attic hatch doorframe and ceiling joists with a sealing gasket much like the ones found on ordinary refrigerators. Or sealing between the attic hatch door and the wood trim around it also works well to ensure maximum efficiency.
There are two approaches to insulating the attic hatch door, creating an insulated cover box and attaching rigid foam insulation to attic facing side of the hatch door. To insulate an attic hatch door with pull down stairs, you'll need a few pieces of rigid foam insulation, such as STYROFOAM™ Brand Residential Sheathing Insulation, and a strong adhesive. Measure, cut, and adhere the rigid foam insulation to form a rectangular box structure that fully covers the hatch opening. Make sure that box is tall enough to cover the stairs attached to the back of the hatch!
Insulating a removable wooden panel hatch door is even easier; it's like making an insulation sandwich! Simply remove the panel, add an adhesive to the attic facing side and lay correctly sized rigid foam insulation onto the adhesive.
Recessed can lights
A few spots that may go overlooked on your attic checklist are the recessed can lighting fixtures. Completing a quick seal around the perimeter of the can lights with a one-component polyurethane foam sealant like GREAT-STUFF™ Gaps & Cracks or a two-component spray foam like FROTH-PAK™ Foam Sealant will ensure you covered all your bases.
When laying insulation over or air sealing around recessed can lights, the applicator should be informed on whether the fixtures are IC (insulation contact) rated or non-IC rated. Wrongly applying insulation to non-IC rated fixtures can create a flammable situation, though most new can lights have a self-resetting thermal switch for safety. In any case, it's a good idea to consult your local code official before starting work.
Important considerations
After any home sealing project, have a heating and cooling technician check to make sure that your combustion appliances (gas- or oil-fired furnace, water heater, and dryer) are venting properly. For additional information on Indoor Air Quality (IAQ) issues related to homes, such as combustion safety, visit the EPA's Indoor Air Quality website.
As with any home building project, and particularly when using foam sealants like GREAT STUFF™ Insulating Foam Sealant or FROTH-PAK™ Foam Sealant, consult the label and Material Safety Data Sheet carefully before use.
My two cents
I'm a member of the Building America Cost Effective Energy Retrofit Team, and we recently confirmed through testing that air sealing and insulating the attic offers the best return on investment, second to the basement.
The EPA agrees, noting that many air leaks and drafts are easy to find because they are easy to feel — like those around windows and doors. But holes hidden in attics, basements, and crawlspaces are usually bigger problems. Sealing these leaks with caulk, spray foam, or weather stripping will have a great impact on improving your comfort and reducing utility bills.
Bottom line: If a large scale energy efficiency renovation doesn't fit within your budget, one of the most important and cost effective things a homeowner can do (even by themselves) is thoroughly air seal and insulate the attic.
For information about proper air sealing and insulation for improved energy efficiency visit the Energy Star website.
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