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Serving Portsmouth, NH and surrounding areas. (603) 956-1359
Hidden gaps in your attic, basement, and walls are draining your heating budget every winter - we find them all and seal them tight.
Air sealing services in Portsmouth, NH find and close the hidden gaps, cracks, and openings where outside air sneaks in and heated air escapes, most jobs on a single-family home are completed in one to two days without disrupting your living space.
Most homeowners think of air leaks as a window or door problem, but the biggest culprits are usually the attic floor, basement rim joists, and anywhere pipes, wires, or ducts pass through walls and ceilings. These gaps are invisible from your living room, but they are working against you every day your heat runs. Air sealing is different from adding insulation - it stops the air movement that makes insulation work less effectively. For best results, air sealing and basement insulation are often done together since the basement rim joist is one of the biggest sources of heat loss in older Portsmouth homes.
Portsmouth has a large share of pre-1940 housing - colonial, cape, and Victorian-era homes built long before energy efficiency was a consideration. These homes leak enormous amounts of heated air, and the improvement after proper sealing is dramatic. Combining air sealing with attic air sealing addresses the two largest heat-loss pathways in most Portsmouth homes at the same time.
Portsmouth winters run from October through April, and a home with significant air leakage works your heating system far harder than it needs to. If your bills feel out of proportion to your home's size - or have crept up year over year without a change in your habits - air leakage is one of the most common explanations.
If you notice a chill near the floor, along baseboards, or around electrical outlets on exterior walls during a Portsmouth winter, that is outside air moving through gaps in your building envelope. This is especially common in Portsmouth's older colonial and cape-style homes, where framing gaps and decades of settling have opened up pathways.
Uneven temperatures from room to room - one bedroom always cold, a top floor that bakes in summer - often point to air leakage rather than an undersized heating system. When air escapes freely from one part of the house, the system struggles to maintain consistent temperatures throughout.
During Portsmouth's cold winters, warm moist air from your living space travels upward through gaps in the attic floor and condenses on cold surfaces - sometimes forming frost on the underside of the roof deck. If you have seen moisture stains or frost in your attic, air leakage from below is often the cause.
We start every job with a blower door diagnostic test - not a walk-around with a flashlight. The test depressurizes your home and tells us exactly where air is moving and how much your home is currently leaking. Then we work systematically through the attic floor, basement rim joists, and all the penetrations where pipes, wires, and ducts pass through framing. We use the right material for each location: spray foam for larger holes, caulk for smaller gaps, and weatherstripping for moving parts. Combining this work with basement insulation in the same visit often makes the most sense since we are already working in that space.
After the work is done, we run a second blower door test so you have before-and-after numbers confirming the improvement. We also handle the documentation for any NHSaves rebate application. For homes with significant attic heat loss, pairing this work with attic air sealing addresses the single biggest pathway where heated air escapes in most Portsmouth homes.
Measures exactly how much air your home is losing before and after work - so you have proof the job was done, not just a promise.
Closes the gaps around top plates, light fixtures, and penetrations where most of a home's heated air escapes.
Seals the framing where your floor meets the foundation wall - one of the most common and most overlooked sources of heat loss.
Closes every opening where pipes, wires, and ducts pass through walls, floors, and ceilings throughout the home.
Portsmouth sits in one of the colder climate designations in the country, meaning your heating system runs hard from October through April - and sometimes into May. That extended heating season means every gap in your home's envelope is costing you money for six or more months of the year. Portsmouth also has a large share of pre-1940 housing built long before energy efficiency was a design consideration. Decades of settling, renovation, and wear have opened up gaps that were never there originally. These homes often have significant air leakage around chimneys, in the attic floor, and along rim joists - all of which are very fixable. Homeowners in Dover, NH and Hampton, NH face the same challenges with their older housing stock.
Portsmouth's coastal location adds a specific challenge: salt air and higher humidity off the harbor mean caulk and foam seals face more degradation over time than in inland areas. A contractor familiar with coastal New Hampshire conditions chooses materials that hold up in this environment. The NHSaves program - funded by utilities including Eversource - offers rebates and subsidized energy audits to Portsmouth homeowners, making this an accessible investment. The U.S. Department of Energy explains the full air sealing process here.
Call or fill out the form and we reply within one business day. We ask a few basic questions about your home's age and what prompted you to call so we arrive prepared with the right equipment.
We perform a blower door test to measure your home's current air leakage rate, then walk through the attic and basement to pinpoint where air is escaping. You receive a written estimate before any work is scheduled.
The crew works through the attic floor, rim joists, and all penetrations using the right material for each location. Most of the work happens in spaces you do not use daily - your living space stays undisturbed.
We run a second blower door test after the work is done so you can see the before-and-after improvement in numbers. We provide documentation for NHSaves rebate applications before we leave.
Free estimate, no obligation. We reply within one business day and include a diagnostic assessment so you know exactly what needs to be done before committing to anything.
(603) 956-1359A contractor who skips the diagnostic test and just caulks around windows is not doing a thorough job. We measure your home's air leakage rate before we start and again when we finish - so you have concrete numbers showing the improvement, not just a receipt.
Pre-1940 colonial and cape homes have irregular framing, older construction techniques, and more penetrations than newer builds. We have worked on dozens of these homes across Portsmouth and know where the leaks hide in houses of that era.
Salt air and coastal humidity degrade standard caulk and foam faster than in inland areas. We choose sealing materials suited to Portsmouth's environment so the work holds up season after season - not just the first winter.
We work with the NHSaves program regularly and provide the documentation you need to claim your rebate. Portsmouth homeowners who qualify can recover a meaningful portion of the project cost, and we make sure you apply correctly. ENERGY STAR seal-and-insulate guidance
Every air sealing job we do is measured, documented, and backed by a contractor who understands the specific conditions Portsmouth homes face. That combination of diagnostic rigor and local knowledge is what separates a thorough job from a surface-level patch.
Insulate and seal the basement rim joist together in one visit - the most efficient way to address heat loss at the foundation level.
Learn MoreFocused sealing of the attic floor where the largest share of a Portsmouth home's conditioned air typically escapes.
Learn MoreSpots fill up fast before heating season - get a free estimate now and have your home sealed before the first hard freeze.