What to know
It depends what the duct is made of
Sheet metal is a hard, non-porous surface. Growth sits on it and can be cleaned off.
Fibreglass duct liner and duct board are porous. The EPA's position is that insulation which has become wet or mouldy cannot be effectively cleaned and should be removed and replaced. That is a different job from duct cleaning, and it is worth knowing which one you are being quoted for.
The moisture decides everything
Both the EPA and the CDC frame mould control as moisture control. Remove growth without addressing why the surface was damp and you have bought yourself an interval, not a solution.
- A condensate drain that is blocked, or a pan that has shifted out of level.
- Uninsulated duct running through humid unconditioned space, where the surface sits below the dew point.
- Return-side leaks pulling humid air in from a crawl space.
- Water arriving from somewhere unrelated — a roof, a plumbing run, or grading around the house.
What to be careful of
Anybody offering a coating, a fogging treatment or a sanitiser as the answer, without first identifying where the water came from, is selling the easy half of the job.
Also be careful of confident identification without testing. Knowing something is growing is not the same as knowing what it is, and the second one requires a laboratory rather than an opinion.
What the EPA says about cleaning generally
The EPA's own guidance is worth knowing here, because it is more cautious than most advertising: duct cleaning has never been shown to prevent health problems, and studies have not conclusively shown that particle levels in homes rise because of dirty ducts. What the EPA does list as reasons to consider cleaning are substantial visible mould growth inside the ducts, vermin infestation, and ducts so clogged that debris is actually being released into the room.
Where we fit
We clean duct systems and we can show you the condition of the accessible ductwork, including where moisture has clearly been present. We do not test, and we do not remediate.
If what you have is a moisture problem or porous material that needs replacing, you should hear that plainly from us rather than receive a quote for cleaning.
Where to start
What is actually in your system is a question about your house, and it takes a look rather than a guess.
Our inspection is free, we will show you what we find, and if the honest answer is that nothing needs doing yet, that is what you will get told.