Air Sealing in Existing Homes

A massive amount of energy is wasted due to cracks, holes, and gaps in your house. Air leakage occurs when outside air enters and conditioned air leaves your house uncontrollably through cracks and openings. Reducing the amount of air that leaks in and out of your home through the sealing of cracks and openings is a cost-effective way to cut heating and cooling costs, improve durability, increase comfort, and create a healthier indoor environment.

Professional air sealing in an existing home is a different process than air sealing homes during the construction phase, but the result is the same — stop air from going in and out of your living space! You may already know where some air leakage occurs in your home, such as an under-the-door draft, but you’ll need to find the less obvious gaps to properly air seal it.

How and Where to Air Seal Existing Homes

The process for air sealing a new construction or extensive home retrofit project and the process for air sealing an existing home differ in that AeroBarrier can be used for the former. For existing homes, we utilize our extensive experience in practical building science, in tandem with diagnostic tools, to locate and permanently seal air leaks. Northeast Air Sealing uses a blower door test which depressurizes a home to provide a reading of total leakage, then using an infrared camera we pinpoint areas of leakage and permanently seal them using an expanding spray foam material or caulking. Areas of focus when it comes to air sealing include: 

  • Attics: Lights, fans, plumbing stacks, chimneys, etc – any hole in the ceiling is called a thermal bypass, or air leak. We spray foam around most of these, including light fixtures, bathroom fans, open wall cavities, and plumbing stacks.
  • Walls: Insulation and/or outlet sealing – put foam backers behind the outlet covers and child-proof plugs to stop air coming out of the outlet holes.
  • Basements/Crawlspaces: There is a lot of leakage in the basement, and since it is accessible in most homes, it is a priority for all home air sealing projects. 

Other ways to stop problematic air leakage include: 

  • Caulk and weatherstrip doors and windows that leak air
  • Cover single-pane windows with storm windows or replace them with more efficient double-pane low-emissivity windows
  • Use foam sealant on larger gaps around windows, baseboards, and other places where air may leak out
  • Cover your kitchen exhaust fan to stop air leaks when not in use
  • Check your dryer vent to be sure it is not blocked, which saves energy and may prevent a fire
  • Replace door bottoms and thresholds with ones that have pliable sealing gaskets
  • Repair damaged siding or roofing, and seal small gaps
  • Keep the fireplace flue damper tightly closed when not in use

Is Air Sealing Necessary?

Air sealing a house increases your comfort by reducing the drafts. It also reduces the amount of time that your heating and cooling systems need to run to keep your home at a stable temperature. A drafty house is more than just a waste of resources — it also means higher energy bills.

Air sealing is crucial for maximizing the performance of insulation, the other major component of the home’s building envelope. The R-value of insulation is determined under the assumption that there will be adequate air sealing around the insulation. Once the insulation is left exposed to air movement (air moving up through your attic floor, for example), the R-value decreases. By employing professional air sealing work, you should expect to start seeing energy savings almost immediately.

Save Energy And Money

Air that leaks through your home’s envelope − the outer walls, windows, doors, and other openings − wastes energy and increases your utility costs. A well-sealed envelope, coupled with the right amount of insulation, can make a real difference in your utility bills.

Increase Comfort

Sealing leaks and adding insulation can improve the overall comfort of your home and help to fix many of these common problems:

  • Outdoor noise pollution
  • Pollen, dust, and insects (or pests) entering your home
  • Humidity issues
  • Ice dams on the roof/eaves

Sealing air leaks from the attic and crawl space reduces the quantity of air leakage while improving the quality of air inside in most cases. And by far, the most logical and convenient time to perform air draft sealing is at the same time that new insulation is installed. The new insulation won’t work like it’s supposed to without doing the air draft sealing. Installing insulation without taking steps to reduce unwanted air infiltration is similar to painting a car without addressing rust spots – it saves a little money in the short term, but the result is disappointing from day one.

Stack Effect

A house works a lot like a smoke stack. In winter, hot air rises through the house until it exits in the attic. In summer, it reverses, causing heat from the attic to push into your home. If the second floor of your home is hotter than the first in the summer, this is a big part of why. There should be no more than a 2-3 degree difference between floors. If you seal off a smoke stack at the top, the bottom, or both, you don’t have a smoke stack. In air sealing a house we are trying to stop the stack effect as much as we can.

Wind Breaker On A Pier Principle

Think about standing on a pier in a stiff winter wind wearing nothing but a t-shirt and jeans. Your teeth are chattering from the cold. You get the option of either a windbreaker or a loose-knit sweater. Which one do you want? The windbreaker, of course. It at least stops the wind, where the wind blows right through a sweater. Ideally, you want both, a windbreaker (air sealing) over a sweater (insulation). That is what you want with your home, wrapping an air seal around your insulation.

*Analogy courtesy of Energy Smart Home Performance

We’re ready to assist you in making your home tighter, and more comfortable! Call Northeast Air Sealing at 603-415-1115 or contact us today.

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