A basement much warmer than upstairs
If the unfinished basement stays toasty in winter while bedrooms run cold, supply ducts are likely leaking heat below grade.
Duct repair and sealing in Kalamazoo
A warm basement and cold bedrooms, dust streaks at duct joints, or a register that barely blows at all usually mean conditioned air is escaping before it ever reaches the room.
- Answered 24/7
- Kalamazoo and Coloma offices
- Price before work
Seal furnace plenums, return drop and filter slot$187 to $428Answered 24/7
Quick answer
Duct repair and sealing closes leaks in your supply and return ductwork. Technicians reconnect separated sections, replace crushed or rusted pieces, brush mastic over seams and joints and wrap ducts in unconditioned spaces with insulation. Many homes are done in one day. Accessible basement ducts are the most straightforward, while sealing inside walls is limited to what can be reached.
Duct systems leak at their joints. Over years of heating and cooling cycles, cloth tape dries and peels, screws back out, and sections get bumped loose during plumbing or electrical work. Leaks on the supply side dump heated or cooled air into the basement, attic or wall cavity. Leaks on the return side pull dusty, unconditioned air from those same spaces into your system.
Our technicians find the leaks, reconnect loose sections, repair damaged duct and seal accessible joints with fiber-reinforced mastic. Where ducts run through attics, garages or crawlspaces, we add or replace insulation so the air holds its temperature. The result is more air reaching the rooms that need it and less of your furnace's output warming spaces nobody uses. It also means less dust drawn in from unfinished areas of the house.
Signs you need duct repair & sealing
Dark dust lines at duct seams
Streaks of dirt along joints show air moving through the gap, which pulls dust in or pushes it out.
A register with weak airflow
A disconnected or crushed branch can drop the air at one register to almost nothing.
Higher bills with no new equipment
Rising heating costs when nothing else has changed can point to leaks that make the furnace run longer.
Musty or attic smells from vents
Return leaks pull air from crawlspaces, attics and garages, bringing their odors into the house.
Condensation on summer ducts
Uninsulated or leaky ducts in humid spaces sweat during cooling season and can drip onto ceilings and floors.
Where ducts leak most in Michigan homes
The worst leaks are usually right at the furnace. The joint where the supply plenum meets the cabinet, the return drop and the filter slot often have gaps you can feel with your hand when the blower runs. Branch takeoffs, where smaller ducts leave the main trunk, are next. In basements with panned joist returns, the edges of the sheet metal against the wood often leak all along their length.
Attic ducts in ranch homes and finished upper floors are another trouble spot. Flex duct can pull away from its collar, and older ducts may have lost their insulation wrap to pests or age. Garages and crawlspaces round out the list. In each case, sealing the accessible joints and reinsulating the runs makes a noticeable difference in how well the system performs.
- Supply plenum and return drop at the furnace
- Filter slot and cabinet panels
- Branch takeoffs on main trunks
- Panned joist return edges
- Attic and crawlspace flex collars
How the repair and sealing work is done
Before sealing, our technicians reconnect anything that has come apart, reattach flex ducts with clamps and replace sections that are crushed, rusted through or torn. Joints are mechanically fastened with sheet metal screws first, so they will not separate again, and then brushed with water-based mastic reinforced with fiberglass mesh on larger gaps. Seams are wiped clean first so the mastic bonds to bare metal.
Mastic stays flexible and holds up to the temperature swings inside ductwork far better than cloth duct tape. Where foil tape is used, it is a rated product applied to clean metal. Ducts in unconditioned spaces get new insulation with a vapor barrier facing out, which keeps winter heat in and stops summer cooling from causing condensation on the duct surface.
Return leaks and why they matter
Supply leaks waste conditioned air, but return leaks can cause a different set of problems. When the return side pulls air from a damp crawlspace, a dusty unfinished basement or a hot attic, that air goes straight into the blower and out to every room. It adds dust, humidity and odors, and it makes the equipment work harder to heat or cool air that was never inside the house.
Return leaks near gas appliances deserve particular attention. A return that pulls hard from a mechanical room can affect how a nearby water heater or furnace drafts. Sealing those leaks is part of what we check during a carbon monoxide safety check. In many homes, return sealing alone cuts down on dust and helps the filter catch more of what passes through.
When repair makes sense and when to replace
Most duct systems can be repaired and sealed for a fraction of what new ductwork costs. If the ducts are the right size and in reasonable shape, sealing and insulating them is usually the best value. Old ducts with heavy rust, undersized trunks or layouts that never delivered enough air to certain rooms are a different story, since sealing will not fix a sizing problem.
Our technician will tell you plainly which situation you are in, based on what the inspection actually shows. If replacement is the better long-term move, we explain why and quote new ductwork alongside the repair option so you can compare. For many homes, the best approach is sealing now and planning larger duct changes for the next time the furnace or air conditioner is replaced.
Typical duct repair & sealing costs in Kalamazoo
| Work | Typical range |
|---|---|
| Seal furnace plenums, return drop and filter slot | $187 to $428 |
| Seal accessible basement trunks and branches | $486 to $1,138 |
| Reconnect or replace a damaged duct section | $164 to $437 |
| Reinsulate attic or crawlspace duct runs | $612 to $1,486 |
| Seal panned joist returns | $238 to $596 |
Sealing jobs around Kalamazoo usually land within these ranges. Your final price is set after the technician sees how much ductwork is accessible and what condition it is in. Compare more jobs in the furnace and AC price guide.
How a duct repair & sealing visit works
- Call and describe what you noticeTell us about weak rooms, a warm basement or dust problems, and we set a time to inspect the ducts.
- Duct inspectionThe technician checks the furnace connections, trunks, branches and any attic or crawlspace runs for leaks and damage.
- Repair plan and priceYou get a clear list of what needs reconnecting, sealing or insulating, with a written price.
- Repairs and sealingLoose joints are fastened, damaged pieces replaced, seams sealed with mastic and exposed runs insulated.
- Airflow recheckWe run the system and check airflow at registers that were weak to confirm the repairs made a difference.
Keep reading
Services that often go with duct repair & sealing
Ductwork Installation & Replacement
New and replacement duct systems designed from room loads, with sealed sheet metal trunks, sized branches and added returns.
Learn moreAirflow & Room Balancing
Static pressure tests, register airflow readings and damper settings that send heat and cooling to rooms that come up short.
Learn moreAir Duct Cleaning
Negative-pressure duct cleaning with rotary brushes, plus blower and coil checks, for homes with debris built up in the ducts.
Learn moreWhere we handle duct repair & sealing
FAQ
Duct Repair & Sealing questions from Kalamazoo homeowners
Can ducts inside finished walls be sealed?
Only the parts we can reach, such as the ends near registers and the connections in the basement or attic. Ducts fully enclosed in walls or ceilings are not accessible for hand sealing without opening drywall. In most homes the largest leaks are at the furnace and in accessible basement runs, so that is where sealing pays off most.
Should duct sealing be done before a new furnace goes in?
It works well either way, but doing it during a replacement is efficient because the system is already shut down and the plenum connections are being remade. Sealing at that time lets the new equipment start out with tight ducts, and the technician can confirm static pressure with everything sealed before setting the blower speed.
Why does my basement get colder after the ducts are sealed?
The basement was being heated by leaks. Once they are sealed, that heat goes upstairs where it belongs, and the basement cools off. If you use the basement as living space, we can add a dedicated supply register or two so it gets heat on purpose instead of by accident.
What is the difference between duct tape and mastic?
Standard cloth duct tape loses its grip as it dries out and heats up, and it often falls off within a few years. Mastic is a paste brushed onto the joint that dries into a flexible seal. It lasts far longer and handles the temperature swings inside ductwork.
Does sealing ducts change how my rooms feel?
Usually, yes. Rooms at the end of long runs often get noticeably more air once the leaks between the furnace and those rooms are closed. Sealing is also a good time to rebalance dampers, since the airflow pattern in the system changes when the leaks are gone.
Need duct repair & sealing today?
Call any hour. Our office answers, sets the visit and tells you what to expect before a technician arrives.