Duct Repair & Sealing in Los Angeles

Most uneven cooling problems in Los Angeles homes are not AC problems — they are duct problems. The system is producing cold air at the manufacturer's specified rate. The air is simply not reaching every room because the ductwork has leaked, sagged, disconnected, or was never balanced correctly in the first place.

Why LA Duct Systems Fail

Los Angeles has a large stock of homes built between 1950 and 1980 with ductwork that is now 50–75 years old. Original installations frequently used cloth duct tape — which dries out and fails within a few years — rather than the metallic foil tape that holds for decades.

Flex duct in attics gets crushed by anyone walking across it, sags under its own weight over time, and can pull free from connections during seasonal temperature swings. Insulation on older ducts deteriorates, allowing conditioned air to lose temperature before reaching the registers. Critters — rodents, raccoons, possums in some neighborhoods — chew through duct insulation and create leaks.

The result, in homes throughout LA: 20–30% of conditioned air never reaches the intended room. You pay to cool the attic.

Common Duct Issues We Find

• Disconnected flex duct — typically at the trunk line connection or at the register boot
• Crushed flex duct from foot traffic in the attic
• Cloth duct tape failure at every joint
• Sagging duct runs creating low spots that restrict airflow
• Holes from rodent activity, often at corners and joints
• Inadequate return air sizing causing the system to operate at high static pressure
• Unbalanced duct design — too much air to one room, not enough to another

Duct Repair Service Costs in Los Angeles

| Service | Typical Cost | |---|---| | Spot repair (single accessible joint) | $150–$300 | | Multiple spot repairs / minor sealing | $300–$700 | | Full system seal (mastic + foil tape) | $500–$1,500 | | Aeroseal automated sealing | $1,500–$3,500 | | Adding a duct run to an underserved room | $500–$2,000 | | Full duct replacement (single-story home) | $3,500–$6,500 | | Full duct replacement (two-story home) | $5,500–$8,500 |

When Sealing Beats Replacement

If your existing ductwork is structurally sound — properly sized, properly routed, intact insulation — but has developed leakage at joints over time, sealing is the right answer. Mastic sealing on accessible joints, supplemented by foil tape, returns the system to near-new performance for a fraction of replacement cost.

If the original system was badly designed — undersized trunks, no proper returns, flex duct routed through attic temperatures without insulation — sealing improves it but cannot fix the underlying problems. Replacement with a properly designed system is the better investment.

A duct pressure test (Manual D + leak measurement) determines which situation applies. We perform pressure testing before recommending replacement so the decision is based on data, not guesses.

Duct Cleaning vs Duct Sealing — Different Services

Duct cleaning removes accumulated dust, debris, and biological contaminants from the interior surfaces of the ducts. It does not address airflow problems or energy losses.

Duct sealing addresses leaks at joints, connections, and damaged sections. It improves system efficiency and room-by-room comfort.

These are different services. If your concern is "one room is always hot" or "my energy bills are high," you need sealing, not cleaning.