Mold and Moisture in Air Ducts: Lewisville Homes
Black specks on a ceiling register are often condensation and dust. Sometimes they are mold. Telling the two apart is the first job, and it should come before anyone sells you a treatment.
Where the moisture comes from
Mold in a duct system needs water, and in a North Texas attic system the water usually has an obvious source once someone looks for it. A supply register that sweats because cold air meets humid room air around a gap in the boot seal. A flex run with a torn outer jacket, sweating in a hot attic and soaking its own insulation. A condensate pan that overflows or drains slowly. An air conditioner too large for the house that cools the air quickly but never runs long enough to dry it.
Confirming it is mold
The EPA's guidance is that you cannot tell whether a substance is mold just by looking, and that a laboratory may be needed to confirm it. A tape or swab sample sent to a lab is inexpensive; the EPA's figure was around $50. It also warns that "settling plate" tests, where a dish is left out to see what grows, are not appropriate, because some mold growth shows up in any house. A company that diagnoses mold from a petri dish left on your counter has told you nothing.
When Texas requires a licence
Texas regulates mold work through the Texas Department of Licensing and Regulation. Remediating mold that covers a total of 25 contiguous square feet or more requires a licensed mold remediation contractor, and the work comes with an assessment by a separately licensed assessor, a written protocol and a notice to the state. Below that size, the law does not require a licence. Most mold found in a single register or the first foot of a run is well below the threshold. Growth through a whole trunk, or across an air handler and its insulation, may not be. If the area is anywhere near that size, ask TDLR or a licensed assessor before work starts.
What fixing it actually involves
The EPA is clear that wet or moldy insulation cannot be cleaned effectively and should be replaced, and that mold returns if the moisture source is not fixed. So a real fix has three parts: stop the water, remove or replace what is contaminated, then clean the hard surfaces that can be cleaned. A biocide spray is at most a small last step, and only on surfaces where the product label allows it. The EPA notes no biocide is registered for fibreglass duct board or fibreglass-lined duct. A quote that is mostly a fogging treatment, with no mention of the moisture or the wet insulation, will look good for a few weeks.
Call for a free quote and describe what you are seeing and where. A local company can tell you whether a lab sample, a cleaning or a licensed remediator is the right next step.
Common questions
Is black dust on a register always mold?
No. Often it is household dust darkened by condensation, or soot from candles. A lab sample answers the question for little money.
Can mold in the ducts make us sick?
Mold can affect people with allergies, asthma or weakened immune systems, and that is a question for a doctor. What the EPA says about ducts is that cleaning makes sense when there is substantial visible mold growth, and that cleaning without fixing the moisture will not keep it away.
Will a UV light fix it?
A UV lamp at the coil can limit growth on the coil surface. It does nothing for a duct that is wet because its jacket is torn. Fix the water first.
Who pays if it is from a roof leak?
That is a homeowners insurance question and depends on the policy. Photograph what you find and keep the lab result before anything is removed.
Also in Lewisville
- Duct Cleaning in Lewisville, TX
- Dryer Vent Cleaning in Lewisville
- HVAC Duct and Air Handler Cleaning
- Duct Cleaning After a Remodel or New Build
Also serving
Mold & Moisture in Ducts is available beyond Lewisville, across Frisco , Denton , Carrollton , Flower Mound and The Colony .
Get a quote for mold & moisture in ducts
Tell us about the house and a local duct cleaning company will get back to you, usually within a day or two. Answered Mon–Sat, 8am–6pm · after hours we call back the same day Or call (945) 313-5984 — most people get an answer faster that way.