Stop Paying to Heat and Cool the Attic, Crawlspace and Walls
Leakage measured with a duct pressurization test, sealed at the joints that matter and retested so you see the improvement in numbers.
Leaky ducts waste conditioned air where you never feel it and pull dusty, humid air in where you do not want it. We measure duct leakage in Acton, CA homes, seal it properly and prove the result.
- Serving Acton, CA since 2008
- NATE and EPA 608 certified
- 24/7 emergency dispatch
- Flat-rate pricing approved first
Where Duct Leaks Hide and What They Cost You
Duct systems are assembled from dozens of pieces: trunks, takeoffs, elbows, boots, plenums and flexible runs, all joined on site. Every joint is a potential leak. Over time, tape dries out and falls away, fasteners loosen, and connections separate when someone works in the attic or crawlspace. Leaks at the air handler cabinet and the plenums are especially costly because they sit where pressure is highest.
When supply ducts leak into an attic or crawlspace, the heating and cooling you pay for never reaches your rooms. When return ducts leak, the system pulls air from those same unconditioned spaces, bringing in dust, insulation fibers, humidity and in some cases combustion gases from nearby appliances. Either way, the equipment runs longer to satisfy the thermostat and rooms at the end of leaky runs suffer most.
Because most ductwork is hidden, leaks are easy to ignore. Testing makes them visible and gives a number to work against.
Dusty rooms, high bills or weak airflow? Call to schedule duct leakage testing and a flat-rate sealing price.
How We Test and Seal Duct Leakage
Sealing without testing is guesswork. This is the sequence that turns it into a measured improvement.
Prepare the system
Registers and grilles are temporarily covered, and a calibrated fan is connected to the duct system, usually at the return or air handler.
Pressurize and measure
The fan brings the ducts to a standard test pressure, and the airflow needed to hold that pressure equals the total leakage.
Locate the leaks
With the system pressurized, we find leaks using theatrical smoke, touch and visual inspection at joints, boots, plenums and the cabinet.
Seal the major leaks first
Plenum connections, cabinet seams, panned returns and trunk joints are sealed before smaller branch joints, since they carry the most air.
Apply the right materials
Water-based mastic is brushed over seams and joints, reinforced with fiberglass mesh on larger gaps, and listed foil tape is used where appropriate.
Retest and report
The leakage test is repeated, and you receive the before and after figures along with photos of the sealed areas.
Sealing Materials and Where They Belong
Not every product sold as duct tape belongs on ductwork. These are the materials we use and why.
| Material | Use | Why it matters |
|---|---|---|
| Water-based duct mastic | Seams, joints, takeoffs, boots and plenums | Remains flexible and adheres long term, the most durable seal for most joints |
| Fiberglass mesh with mastic | Gaps wider than a pencil lead | Bridges larger openings that mastic alone would not span |
| UL 181 listed foil tape | Duct board, flex duct cores and some metal joints | Listed tapes are tested for duct use, unlike cloth duct tape |
| Cloth duct tape | Not used for sealing | Adhesive dries out and fails, often within a few years |
| Aerosol duct sealing | Inaccessible ducts inside walls and ceilings | Pressurized sealant particles collect at leaks from the inside |
For ducts buried behind finished walls and ceilings, aerosol-based sealing reaches leaks that no one can access by hand. We discuss it when testing shows significant leakage in areas that cannot be opened.
Returns, Panned Joists and the Air Handler Cabinet
Some of the worst leaks in homes are not in the round ducts at all. Many older systems use building cavities as return ducts: a sheet of metal nailed across floor joists, a wall cavity or the space under a stairway. These panned returns are rarely sealed and can pull large amounts of air from basements, crawlspaces and wall cavities. Sealing the edges and seams of panned returns, or replacing them with real ductwork, often produces the largest single improvement.
The air handler or furnace cabinet itself leaks at its seams, filter slot and panel edges. A filter slot left open or covered by a loose cardboard flap can pull in unfiltered air right next to the blower. We seal cabinet seams where the manufacturer allows, install proper filter covers and seal the connections between the equipment, plenums and ducts.
Where returns are undersized and starving the system, sealing alone will not fix airflow, and our Ductwork Install And Replace work addresses the capacity problem.
Signs Your Ducts Are Leaking
Rooms that never reach temperature
Rooms at the end of long runs often receive a fraction of the air they should because of leaks upstream.
More dust than your household explains
Return leaks pull dust, insulation and debris from unconditioned spaces and spread it through the home.
Humid or musty air in summer
Return leaks in crawlspaces and basements can draw in damp air, overwhelming the air conditioner's ability to dehumidify.
High bills despite efficient equipment
Efficient equipment connected to leaky ducts delivers only part of its rated performance to the rooms.
Duct Sealing and Indoor Air Quality
Sealing is often discussed as an energy measure, but its air quality benefits can be just as significant. A home with leaky returns in an attached garage or near fuel-burning appliances can pull exhaust gases and fumes into the living space. Return leaks in basements and crawlspaces bring in moisture and particulates that no filter fully handles.
By sealing returns, the system draws air only from the rooms it is meant to serve, through the filter, which improves filtration effectiveness and reduces dust. If you have concerns about specific pollutants, pairing duct sealing with Indoor Air Quality Testing gives you readings before and after.
Insulation Comes After Sealing
Ducts in attics and crawlspaces should be sealed before they are insulated. Insulation wrapped over leaky joints hides the leaks without stopping them. When we seal accessible ducts, we check insulation and recommend adding or repairing it where needed.
Duct Sealing Questions
Newer energy codes set leakage limits for new construction, and many existing homes test well above them. We compare your results to current code targets and typical ranges so you know where your home stands.
Testing takes about an hour. Sealing accessible ductwork in an average home takes several hours to a full day depending on access, the number of joints and the condition of the system.
Hand sealing requires access. For concealed ducts, aerosol sealing works from inside the ductwork and can seal many leaks without opening walls or ceilings.
Sealing typically increases airflow at registers because air stops escaping along the way. In rare cases with undersized returns, sealing reveals a capacity problem we then address with ductwork changes.
Services that pair with Duct Sealing
Measure Your Duct Leakage and Fix It
We test the duct system under pressure, locate the leaks, give you a written flat-rate price to seal them and retest when the work is done so you can see the difference for yourself.