Duct Sealing

Why Duct Leaks Matter

Ducts that run through attics, crawlspaces, garages and unfinished basements lose heated or cooled air through loose joints, open seams and disconnected sections. Leaky return ducts can also pull in dusty, humid or contaminated air from those spaces. The result is higher energy bills, rooms that never get comfortable, a system that runs longer than it should, and sometimes poorer indoor air quality.

Signs of leaky ducts include rooms that are hard to heat or cool, weak airflow at some registers, dust around supply grilles, and high bills compared with similar homes.

How We Seal Ducts

We start by finding the leaks. A duct leakage test pressurizes the duct system and measures how much air escapes, and a blower door test helps show whether that leakage is to the outside. We inspect accessible ductwork, then seal joints, seams, boots and plenum connections with mastic and approved tapes, reconnect loose sections, and insulate ducts in unconditioned spaces where it makes sense.

After sealing we test again, so you get a before-and-after number rather than a guess. Duct sealing is often paired with insulation and air sealing as part of a whole-house plan from a home energy audit.

New Construction & Energy Code

Many energy codes require ducts to be tested for leakage when forced-air systems are installed or replaced. Builders and HVAC contractors can work with us to test and, where needed, seal ducts to meet the requirement. See our contractor testing page for details.

Rebates

Duct sealing may qualify for incentives through Efficiency Maine or NHSaves, depending on the home and program rules at the time. See our rebates page, or ask us when you call.

Frequently Asked Questions

How do I know if my ducts are leaking?

Uneven temperatures, weak airflow, dusty registers and high bills are common signs. The only way to know for sure is a duct leakage test, which measures the leakage directly.

Is duct sealing worth it?

When ducts run through unconditioned spaces, sealing them is often one of the more cost-effective upgrades for a forced-air system. Testing first tells us how much leakage there is to fix.

What areas do you serve?

We are based in Berwick, Maine and serve Southern Maine and Seacoast New Hampshire, including York County towns and Portsmouth, Dover and Rochester. See our Portsmouth and York County pages.