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Air Sealing

Home Performance - Air Sealing

Air sealing is a very misunderstood subject with regard to building and home energy efficiency; it is also a very important, professional service that Shaping Energies provides to a large number of clients.  Air sealing stops the uncontrolled exchange of air from inside your conditioned living space to outdors, and it has a number of other side benefits as well.  We use a blower door test with an infrared camera for thermal imaging and zonal pressure testing techniques to determine what locations in your home are drafting.  Once we quantify how much your home is drafting, and where the air is coming in and leaving from, we can determine how to effectively help you by air sealing and improving the tightness of your home.  The idea of air sealing can seem like a moving target when you consider the abundant number of areas that are drafting in any given house, however, as a Home Performance with ENERGY STAR contractor, Shaping Energies uses a method for prioritizing air sealing opportunities in a manner set forth by BPI (The Building Performance Institute).  That method of prioritizing air sealing is the following:

Prioritized Air Sealing

  • Air seal communication between the attic and the living space first.  Areas to seal include: by-passes around chimneys, ducts, drop soffits, shower inserts or other large penetrations; interior and exterior wall top-plates; and plumbing and wiring penetrations.
  • Leakage paths identified between attached or tuck-under garages and the living space should always be sealed.
  • After establishing an effective air barrier between the attic and living space, basement air sealing may be completed.  Areas to be sealed in basements should be based on the use of the basement area.  Conditioned or tempered basements should be sealed at the rim joist and other connections to outside.
  • Reduce air leakage paths through building cavities by using manual air sealing, high density cavity insulation (like dense packed cellulose or spray foam insulation)
  • If the magnitude of the draft reading on the blower door is still above the Building Airflow Standard (or above the percent draft reduction that was quoted in your contract) after sealing the attic, garage, and basement, interior air sealing may be performed as needed including:  Sealing around plumbing penetrations, caulking around window and door casings, caulking around molding and baseboards, or other significant leakage areas identified using the blower door.

Many air leaks in homes are fairly obvious, such as around windows, doors, and electrical outlets. But others, like those in attics, around chimneys, and through recessed lighting fixtures, are often the more significant sources of energy loss in a home. Sealing air leaks is critical to improving the overall efficiency of your home and will make your heating and cooling system perform better.  Additionally, air sealing in your attic will help prevent snow from melting on your roof and turning to ice as it drips off.  Ice then backs up the roof and damages the roof over time; it also can leak into the attic and damage your home further.  Air sealing in the attic also helps to prevent mold from forming at the underside of the sheathing on the roof.  These are just some of the benefits of air sealing your attic, and these are in addition to the obvious benefit that is saving a bunch of money on your energy bills!