Where are the most common air leaks in a New Brunswick home? | Insulation IQ?

Air leakage is the silent energy thief in most New Brunswick homes. Unlike insulation quality, which you can assess by looking at R-values on a spec sheet, air infiltration is invisible — until you book a blower door test and watch the smoke pencil drift toward a gap you never knew existed. Understanding where these leaks typically occur is the first step toward a warmer, drier, and more energy-efficient home.

The attic hatch is consistently one of the worst offenders in older NB homes. A standard pull-down attic ladder or plywood hatch has almost no insulation value and typically no weatherstripping, meaning conditioned air flows freely in and out of your attic every time the pressure differential shifts. In a two-storey home in Fredericton, a poorly sealed attic hatch can account for a surprisingly large fraction of total infiltration. The fix is inexpensive — an insulated box cover, foam weatherstripping, or a commercially available attic hatch cover — but it's overlooked more often than not.

Electrical outlets and switches on exterior walls are notorious leakage points. The standard single-gang box has gaps around the wire penetrations and an open back cavity that communicates directly with the wall stud bay. In balloon-frame homes built before the 1960s — common in Moncton's older neighbourhoods and the historic areas of Saint John — those stud bays run from the basement to the attic with no fireblocking, meaning a single outlet can connect to a column of air spanning the full building height. Foam gaskets behind the cover plates cost almost nothing and make a real difference.

Plumbing stack and drain penetrations through the top plates of framing, ceiling drywall, and basement rim joists are major leak sites. Where a 3-inch ABS drain punches through the ceiling of a first-floor bathroom into the floor cavity above, there is almost always a gap between the pipe and the rough hole. Spray foam or pre-formed collar seals close these quickly. The same applies to supply and return duct penetrations if you have forced-air heating.

The rim joist — the band of framing that sits on top of your foundation wall and supports the floor system — is consistently rated one of the top three leakage zones in NB homes. It's exposed to exterior temperatures, rarely well-insulated in homes built before 1990, and sits right where the building pressure differential is highest. Spray foam applied directly to the rim joist boards from inside the basement (typically 2 to 3 inches of closed-cell spray foam, bringing it to approximately R-12 to R-20) simultaneously air-seals and insulates in a single operation.

Top plates of interior partition walls that intersect the attic floor are another major pathway. Where a bedroom wall meets the ceiling below the attic, there is typically an open cavity between the drywall and the top plate that connects to the attic air. Blown-in insulation doesn't seal this gap — it requires a deliberate bead of acoustic sealant, caulk, or spray foam along the top plate before insulation is applied.

Recessed pot lights (IC or non-IC rated) penetrate the air barrier at every fixture location. Older non-airtight lights dump conditioned air directly into the attic cavity. Replacing them with airtight, IC-rated fixtures or installing insulated covers from the attic side is a standard part of any professional air sealing package in Climate Zone 6.

Chimneys and fireplace chases create significant stack-effect infiltration in two-storey and split-level homes across New Brunswick. The air gap between the framing and the masonry or metal chimney chase is a direct highway for cold attic air to pour into the home in winter. Fire-rated caulk and sheet metal flashing are used to properly seal these penetrations.

From a numbers perspective, New Brunswick homes built before 1980 commonly test at 8 to 12 air changes per hour at 50 Pascals (ACH50) on a blower door. NB's current building requirements target closer to 3.5 ACH50 for new construction. Comprehensive air sealing — often paired with attic insulation — can cut that number roughly in half in a retrofit context, translating into hundreds of dollars per year in heating savings and potential eligibility for NB Power rebates and the Canada Greener Homes Grant.

A registered energy advisor can identify exactly where your home leaks most and prioritize the repairs. New Brunswick Insulation contractors listed on the New Brunswick Construction Network regularly work alongside energy auditors to tackle air sealing as part of a whole-home upgrade.

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Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• Gionetterenovations
• Brunswick insulation & roofing
• 3Tone Construction Ltd
• moose luxury painting
• Thirty Four Renovations