The question people ask on the phone is “how old is too old?” The answer is that age is close to irrelevant. Sixty-year-old galvanised trunk in a dry basement can be in better condition than fifteen-year-old flex in an attic that has been used for storage.
What decides it is condition, material and whether the run was ever the right size.
Repair territory
Sound rigid metal with unsealed seams. This is the most common finding and the best outcome. The metal is fine; the joints were never sealed, or were sealed with tape that has since let go. Mastic and mechanical fasteners fix it permanently.
A disconnected boot or branch. A run that has come apart is reconnected, fastened, sealed and supported. Dramatic symptom, straightforward repair.
Sagging or unsupported runs. Re-hung at proper intervals, with flex pulled taut rather than draped. This alone can restore a surprising amount of airflow.
Localised damage. A crushed section here, a torn piece there. Cut it out, replace that piece, seal both new joints.
Replacement territory
Flex that has been compressed for years. Flexible duct has no memory. A box left on a run for a decade leaves a permanent restriction, and sealing the ends of a crushed run does nothing about the middle.
Corrosion through the seam. Metal that has rusted through, usually in a damp crawlspace or where a condensate line has been leaking onto it. Sealing a corroded joint moves the failure a few feet along.
Insulated flex that has been wet. The insulation holds whatever got into it. In flood-corridor areas such as Manville, Bound Brook or the Passaic River towns, this is a regular finding after a wet basement, and cleaning it is not the answer.
Branches that were undersized from the start. If a room has never held temperature since the house was built, the branch is probably too small for it. No amount of sealing changes cross-section. This is a resize, which is installation work.
Ducts in a space they should never have been in. Occasionally we find a supply run through a space with an obvious moisture or contamination source. Moving it beats maintaining it.
The middle case, which is most houses
Real systems are rarely all one thing. The common outcome is that most of a system is repairable and one or two sections are not: a sound trunk with unsealed seams, plus one crushed flex branch to the back bedroom.
The right answer there is to seal what is sound and replace the section that is not. Anyone proposing a whole-system replacement should be able to point at the specific runs that justify it, in photographs.
Questions worth asking before you agree to anything
- Which specific runs are you proposing to replace, and can I see the photos?
- What is wrong with them: material condition, sizing, or route?
- What are you sealing rather than replacing, and with what?
- If we repair rather than replace, what is the realistic expectation?
- Does this change how the rest of the system behaves?
That last one matters and gets skipped. Ductwork is a network. Enlarging one branch changes the balance of everything else on that trunk, so a change to one room can quietly make another worse.
Where cleaning fits
Cleaning and repair are different services and they answer different symptoms. Cleaning removes what is inside the duct. Repair addresses the duct itself.
If a system is coming apart, cleaning it first is usually the wrong order: repair it, then clean it, then the photographs at the end mean something. If it is sound but dirty, cleaning is the whole job.
We inspect for both on the first visit because the two are hard to separate from outside, and the honest recommendation depends on which one your house actually has. The repair page describes what the inspection covers; if it turns out to be a cleaning question, that page is here.
