Leaky ductwork can waste as much as 20 to 30 percent of the air moving through a forced-air system before it ever reaches a single room. In many Exeter homes, that lost air escapes into attics, crawl spaces, and wall cavities where it does nothing but drive up energy bills and leave certain rooms uncomfortable. Duct sealing addresses this problem directly, and at Paul the Plumber we treat it as one of the most cost-effective improvements a homeowner can make to an existing heating and cooling system.
How Air Loss Happens Inside a Duct System
Ductwork is assembled from sections of sheet metal, flexible tubing, and fittings that are joined at seams, elbows, boots, and takeoffs. Over the years, the tape and mastic used at those joints dries out, cracks, and separates. Temperature swings between summer cooling and winter heating cause the metal to expand and contract, which loosens connections that were once tight. Vibration from the blower motor slowly works fasteners free, and rodents or careless prior work can pull sections apart entirely.
Once those gaps open, conditioned air pushes out under pressure while unconditioned air gets pulled in on the return side. The result is a system that runs longer to reach the thermostat setting, cycles more frequently, and delivers uneven temperatures from room to room. In an Exeter home with ducts routed through an unheated basement or a vented attic, the losses can be severe enough that entire rooms never feel comfortable no matter how the thermostat is adjusted.
Our Duct Sealing Method Step by Step
When our technicians arrive, we begin with a thorough inspection rather than assumptions. We trace the supply and return runs, identify accessible joints, and look for the telltale signs of leakage such as dust streaking around seams, disconnected sections, and crushed flexible duct. Where the system allows, we perform pressure testing to measure how much air escapes before any work begins, which gives us a baseline to compare against after the repair.
The sealing itself uses materials chosen for the specific joint being treated. Our process typically follows this sequence:
- Cleaning the surface: We wipe down each joint so sealant bonds to bare metal instead of accumulated dust.
- Applying mastic: We brush a water-based mastic over seams and connections, which stays flexible and does not crack the way old cloth tape does.
- Reinforcing with mesh: On wider gaps we embed fiberglass mesh into the mastic to bridge the opening and hold the seal.
- Securing mechanical joints: We add sheet-metal screws where connections have worked loose so the seal is not carrying structural load.
After the mastic cures, we retest where possible to confirm the improvement. Every step is documented so you understand exactly what was found and what was corrected. Because we are family owned and operated, we approach each home the way we would want our own treated.
Technical Details That Affect Performance
Not all duct sealing produces the same result, and the difference comes down to detail. The static pressure inside a residential duct system is measured in inches of water column, and even small leaks at high-pressure points near the air handler cost far more than larger gaps at the far end of a run. For that reason we prioritize the sections closest to the blower, the plenum connections, and the return-air boxes, since these carry the greatest pressure and the largest potential savings.
Material selection matters as much as location. Foil-backed tape rated to UL 181 standards performs well on clean metal, but mastic remains the more durable choice for irregular surfaces and long-term flexibility. We also pay attention to the balance between supply and return airflow, because sealing only the supply side can create pressure imbalances that pull outside air through other paths. Proper duct sealing considers the system as a whole, not just the visible cracks.
The Comfort and Efficiency You Can Expect
Homeowners who have their ducts sealed often notice results the same day. Rooms that once stayed too warm in summer or too cold in winter begin to hold their temperature. The heating and cooling equipment cycles less often, which reduces wear on the compressor and blower and can extend the working life of the whole system. Because less air is escaping into attics and crawl spaces, indoor humidity becomes easier to control and dust drawn in through return leaks is reduced.
These benefits build on one another. A tighter duct system lets a properly sized furnace or air conditioner do its job without straining, which improves both comfort and energy consumption. For families dealing with allergies, sealing return-side leaks means less unfiltered air carrying pollen and dust into living spaces. The improvement is measurable on utility bills and noticeable in day-to-day living.
Why Homeowners Choose Paul the Plumber
We have built our reputation on doing careful, honest work, and duct sealing is a service where that care truly shows. We have been in business for 22 years, and in that time we have refined our methods around what actually delivers lasting results rather than quick fixes. We are BBB accredited with an A+ rating, and we carry thousands of verified five-star reviews across multiple review platforms.
Every technician who enters your home is licensed and background checked, so you can feel secure with our team on the property. We offer up-front pricing before any work begins, and we back all of our work with a two-year parts and labor warranty. Homeowners who join our club membership receive an extended three-year parts and labor warranty. A few reasons customers keep calling us back include:
- Straightforward pricing: You know the cost before we start, with no surprises added later.
- Reliability and integrity: We show up when we say we will and stand behind the work we do.
- A family mindset: We treat customers like family and treat our employees the same way, because we genuinely care.
Alongside duct sealing, we provide complete plumbing, HVAC, and electrical services including AC installation, AC repair, and HVAC repair. Whether you are searching for a plumber near you here in Exeter or across our wider service area in Derry, we are happy to help and always offer service with a smile. Reach out to Paul the Plumber to schedule your duct sealing evaluation.
