What’s the difference between air sealing and insulation?
Let’s explore the idea of air sealing… 99% of homeowners think that all they need is insulation on the other side of the ceiling to keep their home comfortable. Yes, insulation is important- it helps to keep your home warm in the winter and cool in the summer by controlling heat that is transferred by way of conduction.
However, insulation does not actually stop air movement. In fact, most insulation will allow air to flow right through it. When that happens, the benefits of the insulation are eliminated.
Try thinking about the relationship between insulation and air sealing as a “sweater and windbreaker” partnership. Pretend that you’re going outside on a winter day. The temperature is about 25 degrees with a 15 to 20 mph breeze blowing. A knit sweater may seem warm for a few minutes, but then the cold air finds its way through all of those holes and you begin to realize you need a nylon shell to block the wind. That’s exactly what air sealing does for insulation! The two work together to make your home comfortable and energy efficient.
Why you should I air seal my home?
In addition to making insulation more effective, there are other reasons why air sealing a home is critical:
Reduces the “stack effect” in a home
Prevents moisture from getting into the attic and creating problems with condensation, mold, etc.
Keeps nasty attic air from coming down into the living space
Decreases some of the general drafts in a home
Where are the air leaks?
“Wait a minute,” you say. “I don’t see any holes in my ceiling. What exactly are you talking about?” Great question! Very few of the bypasses in your ceiling are noticeable, especially from the interior of the home. Most of the holes drilled for light fixtures, particularly recessed lights, are hidden behind trim pieces. Nevertheless, those openings still leak air. A majority of the areas of leakage are only seen from the attic, which is why it is essential for an energy efficiency auditor, home inspector or contractor to actually go into the attic to look for the following:
Wiring holes in top plates
Gaps and cracks where the ceiling meets the top plates
Interior attic hatches
Chase cavities for the furnace flue, chimneys, HVAC ductwork, plumbing, etc.
Unsealed interior soffits or dropped ceilings
Pull-down attic stairs (the absolute worst if they are inside the home!)
It is estimated that the average home has combined air leakage in the ceiling that’s the equivalent of having a 3-by-4 foot window open at all times. If you found an open window, we bet that you would shut it in a heartbeat. Why wouldn’t you also want to “shut the openings” in your ceiling?
