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This is the second in a series of articles on the most important steps to take when assessing and improving your home’s energy efficiency. In the first post, we discussed the blower door test, which can highlight where leaks are occurring in your home. In this article, we’ll review the next step: air sealing.

As someone who’s worked in the energy-efficiency industry for years, on sites across North America, I’ve explored a wide range of home types. From 200-year-old Victorians on Boston’s Tremont Street to low-income condominiums in Toronto, there’s one thing that unites the vast majority of them: they leak. New, old, high-quality construction, or something less than — it doesn’t matter. Somewhere in the walls, the floors, or the ceilings, gaps are letting in air that doesn’t belong, and it’s driving down your quality of life.

Identifying the Gaps

In my last post, I discussed the importance of getting an energy audit, beginning with a blower door test run by a qualified professional, to assess the air tightness of your home. As a reminder, the blower door test works by dropping the air pressure in your home so specialists can use smoke or incense to visually spot leaks where air is being sucked into or out of your home.

Leaks commonly occur where features of your home meet or intersect. Think gaps around water pipes or duct work, window panes, can lights in your ceiling, your attic floor or “plane,” and the floorboards above your crawl space. Quality air sealing by an experienced professional can mitigate the problems caused by leaks: inconsistent or uncomfortable temperature, poor indoor air quality, and sky-high energy bills.

Sealing Your Home

What can you expect as part of the air sealing process? Once a contractor identifies the leaks in your home, they’ll typically discuss the scope of the sealing work, and you’ll agree on just how much you want to seal.

Your attic or roof plane — in other words, the membrane between conditioned and non-conditioned air in your home — is a good place to start because it can account for much of your lost air. Your contractor will look for leaks under your insulation, between the ceiling joists and the sheetrock, around can light fixtures, and in corners where the sheetrock meets the wall.

If your insulation is old, they may recommend replacement, which we’ll talk about in our third installment of this series, but for homes with newer insulation, spray foaming the gaps may be enough to seal the plane. Once they’re confident they’ve found and sealed all gaps in the attic plane, top contractors will run the blower door test again to see just how much leakage you’re now saving.

On lower levels, contractors will typically caulk leaky windows and door frames, examine and use spray foam on gaps around water pipes under sinks or behind appliances and remove the face plates off outlets to caulk up any gaps around the boxes housing electrical wires. This kind of sealing is especially important on exterior walls.

If your first floor rests on a crawl space, your contractor may recommend more spray foam for gaps in the construction of your floor, or full weatherization, which means running heavy-duty sheeting on the inner perimeter of the crawl space, effectively creating a protective barrier between your floors and the air in the crawl space, including the appropriate level of insulation.

Measuring Your Success

Regardless, at the end of the sealing process, your contractor will run a final blower door test and inspection to ensure that all identified and scoped leaks have been sealed. And you’ll be well on your way to a more comfortable, healthier, and efficient home. Next up, the third step to a high-performing home: Insulation.

Interested in starting your journey to a healthier, more comfortable, and more efficient home? Log in to Green Door, Pearl’s award-winning home management app, to get customized home improvement recommendations, connect with top professionals in your area, and certify your upgraded assets.


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