Sealing and insulating the “envelope” of your home (walls, ceiling, windows, doors, floors) is typically the most cost effective way to improve energy efficiency and comfort. The Department of Energy’s ENERGY STAR estimates that a home owner or skilled contractor can save up to 20% on heating and cooling cost (or up to 10% of their energy cost) by air sealing and insulating.

  • Seal air leaks throughout the home or building to stop drafts,
  • Add insulation to prevent heat loss in winter and heat gain in summer,
  • Select ENERGY STAR qualified windows when replacing windows.

You can Do-It-Yourself with help from Energy Star’s DIY Guide. This guide offers step-by-step instructions for sealing air leaks and  insulation to the attic.

You can also hire a contractor who will use diagnostic tools to pinpoint and seal any hidden air leaks. Look through the phone book yellow pages to find contractors that offer air sealing services in your area. There are also qualified contractors that participate in local Home Performance with ENERGY STAR programs across the nation.


Most air leaks and drafts are easy to locate because they are quite easy to feel — like those around windows and doors. Holes hidden in attics, basements, and crawlspaces are typically bigger problems. Sealing up these leaks with one component polyurethane foam sealant like Great Stuff Pro, spray foam, or weather stripping will have a great impact on improving your comfort and reducing utility costs. See the house diagram below to see common air leak locations that you should aim to seal.

Some homeowners are concerned about sealing their house too tightly. It is a concern but  this is very unlikely in most older homes. A certain amount of fresh air is needed for good indoor air quality and there are specifications that set the minimum amount of fresh air needed for a house. If you are concerned about how tight your home is, hire a contractor, such as a Home Energy Rater, who can use specialize diagnostic tools to measure your home’s actual leakage. If your home is too tight, a fresh air ventilation system may be recommended.

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.


Common Air Leaks in a Home

Insulation keeps your home warm in the winter and cool in the summer. There are several common types of insulation — fiberglass (in both batt and blown forms), cellulose, rigid foam board, and spray foam. Reflective insulation (or radiant barrier) is another insulating product which can help save energy in hot, sunny climates.

When correctly installed with air sealing, each type of insulation can deliver comfort and lower energy bills during the hottest and coldest times of the year.

Insulation performance is measured by R-value — its ability to resist heat flow. Higher R-values mean more insulating power. Different R-values are recommended for walls, attics, basements and crawlspaces, depending on your area of the country. Insulation works best when air is not moving through or around it. So it is very important to seal air leaks before installing insulation to ensure that you get the best performance from the insulation.

To get the biggest savings, the easiest place to add insulation is usually in the attic. A quick way to see if you need more insulation is to look across your uncovered attic floor. If your insulation is level with or below the attic floor joists, you probably need to add more insulation. The recommended insulation level for most attics is R-38 (or about 12–15 inches, depending on the insulation type). In the coldest climates, insulating up to R-49 is recommended.


Foam sealant is perfect for sealing gaps around HVAC ducts

In houses with forced-air heating and cooling systems, ducts are used to distribute conditioned air throughout the house. In a typical house, however, about 20 percent of the air that moves through the duct system is lost due to leaks and poorly sealed connections. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set.

Because some ducts are concealed in walls and between floors, repairing them can be difficult. However, exposed ducts in attics, basements, crawlspaces, and garages can be repaired by sealing the leaks with duct sealant (also called duct mastic). In addition, insulating ducts that run through spaces that get hot in summer or cold in winter (like attics, garages, or crawlspaces) can save significant energy.

Gaps around HVAC duct vents are common air leakage points and should be sealed up with polyurethane foam sealants like Great Stuff Gaps & Cracks. The foam sealant expands to fill up the gaps around the HVAC vent as well as adding extra insulation. To seal up additional gaps and cracks around the house, it is much easier and less messier to use a professional foam sealant that dispenses foam via a foam dispensing gun like the Foam N’ Seal FNS500.

Additionally, if you are replacing your forced-air heating and cooling equipment, make sure your contractor installs the new system according to ENERGY STAR quality installation guidelines. A quality installation will include a thorough inspection of your duct system, including proper sealing and balancing of ductwork, to help ensure that your new system delivers the most comfort and efficiency.


Helpful Tip: A foam dispensing gun is helpful for bigger projects as it is less messy and the foam sealant can be reused for up to 30 days. Manufacturers offering foam dispensing applicators or tools include: Foam N’ Seal, Great Stuff Pro 13, 14, 14 XL, 15 Pageris, Fomo Handi-Tools, Convenience Products Touch ‘n Foam and Touch ‘n Seal Sharpshooter pro foam guns.


(Source credit: US Department of Energy)

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