Duct sealing and repair
The least glamorous service on this site and, for most Arlington homes, the one that returns the most money. Almost nobody selling duct cleaning offers it.
The problem
The problem, in one sentence
Your ducts run through an attic that bakes on an Arlington August afternoon, and every unsealed joint in that ductwork is leaking air you have already paid to cool.
It works in both directions, which is what makes it expensive. Supply leaks dump cold air into the attic. Return leaks pull superheated attic air into the system, so the air handler is now cooling attic air instead of house air. The second one is worse and much less obvious.
The value case
Why this beats cleaning on value
Duct cleaning improves something difficult to measure. Duct sealing improves something you can put a number on: how much of the air your system moves actually reaches the rooms.
In a climate with a six-month cooling season, that difference compounds every month. A system losing a meaningful share of its output into an attic is running longer to hit the same thermostat setting, which costs electricity and wears the equipment.
We put this above cleaning on our own list of what is worth doing, and we are aware that is an odd position for a site with "air duct" in the name.
Where they leak
Where the leaks are
- Joints and seams in flexible duct at the connection collars: the most common failure by a wide margin.
- The plenum where ductwork meets the air handler. Often sealed with tape at build and long since failed.
- Register boots where the duct meets the ceiling or floor, frequently not sealed to the drywall at all.
- Crushed or kinked flex runs, sometimes squashed by insulation contractors or anyone who has been in the attic since.
- Disconnected runs. More common than you would think. A branch that has come off its collar is conditioning your attic full-time.
The method
How it is done
Manual sealing means mastic, a thick paste brushed onto every joint, often with mesh tape at larger seams, plus mechanical fastening where connections have loosened. Mastic is the correct material. Cloth duct tape, despite the name, dries out and fails in attic heat, and finding it on your ductwork tells you when it was last touched.
Aerosol sealing from inside the duct exists as an alternative and works, at higher cost. For most Arlington homes with accessible attic ductwork, manual mastic sealing is the sensible option.
Repair is the other half. Crushed sections get replaced rather than sealed, disconnected runs get reconnected properly, and badly undersized returns (a common original-build shortcut) get enlarged.
Permits
Permits apply here, unlike cleaning
This is the distinction worth knowing. Cleaning ducts requires no permit. Altering or replacing them does: Arlington requires a mechanical permit for ductwork changes, replacements and venting modifications, under the 2021 International Codes adopted by the city in late 2022, with applications through the Accela portal.
Sealing existing joints is maintenance. Replacing runs is not. If a contractor proposes replacing ductwork, ask whether they are pulling the permit. If the answer is that it does not need one, ask them to confirm that with the city rather than with you.
Straight answers
Sealing questions worth asking
How do I know if my ducts leak?
A duct blaster test measures it properly. Cheaper indicators: rooms that never reach temperature, a system that runs almost continuously in July, or visible dust streaking around register edges, which shows air moving where it should not.
Can I seal them myself?
Accessible joints, yes: mastic is inexpensive and the work is straightforward, if unpleasant in an attic. Just don’t use cloth duct tape. Anything requiring you to crawl over joists in an August attic is worth paying someone for.
Should I seal before or after cleaning?
Clean first if both are warranted, so you’re not sealing debris into the system. In practice many homes need sealing and not cleaning.
Is it worth insulating the ducts too?
In a Texas attic, yes. Sealing stops the air escaping; insulation stops what stays inside from gaining heat on the way to the room. They are usually quoted together and should be.
What about replacing everything?
Occasionally justified for old, crushed or badly undersized systems. Frequently proposed when sealing would do. Get the leakage measured before agreeing to replacement, and remember that replacement is permitted work.
Will this help with uneven room temperatures?
Often, yes. A disconnected or crushed run is one of the most common causes of a single room that never cools. It’s worth checking before anyone suggests a bigger system.
Start with a survey, not a sales visit
Ask about sealing
If a room never cools, or the bills climb with no change in habits, this is usually a better first call than cleaning. Tell us which rooms and we will start there.
Related work we arrange
What else we look at
Air duct cleaning
Whole-system source removal to the NADCA method: negative pressure on the trunk, agitation in every branch. Not a vacuum poked into a vent.
Dryer vent cleaning
The one job in this trade with a documented fire-safety case behind it. Long duct runs in Arlington two-story homes make it worse.
Coil and blower cleaning
Where the measurable efficiency loss lives. A fouled evaporator coil costs you more each August than dusty duct walls ever will.
Duct mold inspection
One of the three conditions the EPA says does warrant cleaning. Testing first, because "it looks like mold" is not a diagnosis.