DUCTWORK REPAIR & SEALING IN SALT LAKE CITY

The most efficient 96% AFUE furnace in the valley is still wasteful if a quarter of the heated air leaks out of the ducts on the way to your registers. Leaky ductwork is the single most-overlooked efficiency problem in Utah homes, and it's the reason some rooms never reach setpoint while others get blasted with hot or cold air. It's also the reason dust accumulates faster in certain homes, humidity control suffers, and HVAC equipment runs longer than it should.

We see the same pattern on homes across the Wasatch Front. Stucco homes in Kearns and Sandy built in the 1990s with flex duct run through unconditioned attics — joints disconnected at plenum, insulation missing, connections not sealed. Tri-level and split-level homes in Taylorsville and West Jordan where the furnace feeds both floors through undersized trunks. Older Avenues homes where forced air was retrofitted into plaster walls and the returns are too small for the system. Basement remodels in Sugar House and Holladay where the original builder's ducts now serve 40% more conditioned space than they were sized for.

What duct problems cost in real dollars

A typical Utah home with moderately leaky ductwork (15-25% loss) is paying an extra $300 to $600 per year on heating and cooling. Over a decade, that's $3,000 to $6,000 in wasted gas and electric. A proper seal-and-repair job — usually $1,800 to $4,500 depending on access and scope — pays back in 4 to 8 years on utility savings alone, and the comfort improvement is immediate.

Common ductwork problems

• Disconnected flex duct at plenum — most common single issue in Utah homes, tape and strap failure
• Crushed or kinked flex duct — tight turns, something dropped on it during construction or a home inspection
• Undersized trunk lines — original builder cheap-out, especially in split-level and tri-level homes
• Missing or wrong return air — not enough return capacity, furnace chokes on airflow
• Leaky sheet metal joints — older rigid ductwork with mastic that's dried and cracked over 20+ years
• No insulation in unconditioned spaces — attic and crawlspace ducts need R-8 minimum, most older systems have R-4 or nothing
• Unbalanced airflow between rooms — specific rooms too hot or too cold, damper adjustment and sometimes resizing needed

How we diagnose ductwork issues

Two tools do most of the work. A pressure-based blower door and duct blaster test measures total leakage in cubic feet per minute at 25 pascals — this is the standard energy-code metric and it tells us objectively how much your system leaks. Then we visually inspect with a lighted probe and camera, pulling insulation to look at joints, checking flex duct runs, measuring trunk sizes against load calculations. The combination tells us where the leaks are and how big.

Sealing options

Manual sealing with mastic and foil tape — tried and true, works where we can access the joints. Mastic adhesive brushed onto every seam, foil-backed butyl tape on the major connections, strap-and-screw on flex-to-rigid transitions. $1,500 to $3,500 for a typical home depending on accessibility.

Aeroseal interior sealing — breakthrough tech for hard-to-reach duct leaks. A polymer aerosol is pushed through the duct system under pressure; as it hits leaks, it accumulates and seals from the inside without needing to access the exterior. Works on attic flex, inside wall chases, anywhere traditional sealing can't reach. $2,500 to $4,500 for most homes. Best single-biggest-impact intervention on leaky systems.

Replacement of bad sections — if flex duct is collapsed, crushed, or just too old to seal, we replace the run with new insulated flex or rigid sheet metal. Priced by linear foot of duct plus register boxes and connections. $15 to $35 per foot of replacement flex installed, more for rigid sheet metal.

New construction and full duct design

For major remodels, additions, or complete duct replacement, we do Manual D duct design calculations alongside the Manual J load calculation. That means the entire system is sized correctly: right trunk sizes, proper branch runs, balanced register sizing per room, and enough return capacity for the actual equipment. Most existing residential ductwork in Salt Lake homes was not designed this way — it was rules-of-thumb and builder convenience. Doing it right on a remodel pays for itself in every category we care about.

Registers, grilles, and balancing

The final step on most ductwork projects is room-by-room airflow balancing. Registers have dampers; we adjust them to deliver the right volume to each room based on the heat load. Bigger south-facing rooms get more air in summer; colder north-facing rooms get more in winter. On systems with zone dampers, we calibrate the damper positions and confirm the bypass is working correctly. A well-balanced system feels even across the house and the equipment cycles appropriately.