Air sealing is one of the most critical features of an energy efficient home. To prevent air leakage, it is best to seal the building envelope during construction prior to installation of the drywall. A “blower door” test is a good way to identify air leakage paths so that they can be sealed using an appropriate material.
Why Do You Need To Air Seal?
Lower Energy Bills Air leakage accounts for 25 percent to 40 percent of the energy used for heating and cooling and also reduces the effectiveness of other energy efficiency measures such as increased insulation and high-performance windows. Thus air sealing results in lower energy bills.
The Stack Effect This is the main reason to air seal your home. A house works a lot like a smoke stack. Hot air rises through the house until it exits in the attic. 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.
Fewer Condensation Problems Condensation can lead to mold and mildew problems. In hot, humid climates, moisture can enter into wall cavities through exterior cracks and result in costly damage to framing and insulation. In cold climates, gaps in the interior walls allow moisture from warm indoor air to enter wall cavities and attics. This moisture can condense on cold surfaces and lead to structural damage. By significantly reducing air leakage, you can reduce or eliminate these problems
What Is Air Sealing?
Air sealing is the systematic finding and sealing of air leakage points throughout your home, from the attic to the walls to the basement and/or crawlspace. Here is a brief breakdown of the process for the various parts of your home .
Attic Air Sealing:
Lights, Fans, Plumbing Stacks, Chimneys, etc. - Any hole in your ceiling is called a thermal bypass, or air leak. We spray foam around most of these, including around light fixtures, bathroom fans, open wall cavities, and plumbing stacks. Other items like chimneys and recessed lights require special methods. There are a large number of items that require a professional to find and correct properly.
Wall Air Sealing:
Insulation and/or Outlet Sealing – The simplest item on walls is to put foam backers behind the outlet covers and child proof plugs to stop air coming out the outlet holes. The harder part is insulating walls. If you have a newish home, about 1970 or later, your walls are probably insulated. If you have an older home, especially before 1965, your walls are probably empty. Empty walls generally account for 20-40% of air leakage, and are the best area to reduce leakage. We can insulate most walls and drastically reduce both the air leakage and energy bills of your older home.
Basement/Crawlspace Air Sealing:
There is a lot of leakage in the basement, and since it is accessible in most homes, it is a priority for us.