Sheet Metal & Ventilation · Property Services

Duct Sealing & Leak Testing

Leaky ducts waste a surprising amount of heating and cooling by pushing conditioned air into attics and crawlspaces. Sealing and testing can lower energy bills and improve comfort. NorTech connects you with vetted HVAC contractors who set their own price and show you the numbers before and after.

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How leaks happen and why they matter

Ducts are connected with joints that loosen over time, and old tape dries and fails. Leaks in return ducts can pull dusty attic air into the house, while supply leaks waste conditioned air. In many homes, a significant share of the air never reaches the rooms. Leakage can cause hot and cold spots, high bills and poor indoor air quality. A test measures how bad the problem is. Make a list of the rooms that are too hot or cold and share it, so the technician knows which duct runs to check first.

Testing and sealing methods

A duct blaster pressurizes the system and measures air leaking out. The technician then seals joints with mastic paste or approved foil tape, not cloth duct tape. Disconnected runs are reattached, crushed sections repaired and supports added. After sealing, a second test shows the improvement. Many energy programs and building codes require testing to a leakage standard. Ask to see the before-and-after leakage numbers and where the major leaks were found, and request photos of the repairs.

Insulation, access and what to expect

Ducts in unconditioned spaces should be insulated, and torn insulation repaired. Crawlspaces and tight attics make access hard, so costs vary. Expect to see before-and-after numbers. Combine sealing with filter upgrades and balanced airflow for best comfort. Keep the report for rebates and for resale. Keep the test report with your HVAC records, since rebate programs, inspectors and future buyers may ask to see it. Ask the technician to show you the worst leaks while the system is pressurized, since seeing them makes the value of the work clear.

When to book duct sealing & leak testing

Some rooms are hot or cold.

Your energy bills are high.

Dust and attic air enter your home.

You are replacing HVAC equipment.

Code or a rebate requires duct testing.

You have old or damaged ducts.

90-Day Warranty

Backed by your provider’s warranty. If covered work fails, your provider makes it right — free.

Frequently asked

Duct Sealing & Leak Testing — common questions

It measures how much air leaks from the duct system when pressurized. The result is compared with code or rebate standards. A short walkthrough at the end lets you confirm that everything was finished as agreed.

Standard cloth duct tape dries out and lets go within a few years. Technicians seal joints with mastic paste or listed foil tape, which stay flexible and tight for decades.

Savings depend on how leaky the ducts are. Many homes see noticeable improvements. A clear scope of work protects both you and the provider. Mention any special conditions at your property so the plan fits them.

Often half a day to a day. Photos and written notes make it easier to document and compare options. Tell the provider about pets, children or neighbors who may be affected by the work.

New HVAC installations often require testing. Retrofit sealing may not, but rebates might. Ask for the answer in writing so you can compare it with other quotes. Photos and written notes make it easier to document and compare options.

The contractor guarantees sealing workmanship for 90 days. Test results describe conditions on the test day. Compare what each quote includes rather than just the bottom-line number.

Didn’t find your answer? Nova, our AI assistant, is in the chat bubble in the bottom-right corner and can help anytime.

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