What’s in Your Ducts? Visible Mold!

Air Duct Mold Remediation in Houston

June 9, 2020

Are you concerned about the possibility of dirt or mold build-up in your air ducts, but aren’t sure how to identify the problem? Don’t worry—we can help! In this post, we’ll discuss the visible signs of contaminated air ducts, and then we’ll walk you through the process of getting those ducts spic and span, and spotless once again.

Although this post only discusses visible symptoms of dirt or mold accumulation in the air vents, there are two other fairly common symptoms of contaminated airways: musty odors, and an increase in indoor allergies.


One of the hazards of living in Houston, or anywhere along the Gulf Coast, is that along with all that moisture that we get in the air, we’re also getting a lot of mold spores. For the most part, this isn’t a big deal, it’s just a fact of life—there will be mold spores in the air. But, if those mold spores end up settling in your air ducts, and the conditions are right for them to become comfortable there, then you’ve got problems.

An obvious sign that moldy locks is on the loose in your home or office is that you’ll find little specks of black stuff growing around the air vents. Or maybe you’ll see little specks of black stuff on your desk when you get into the office in the morning.

In the photo above, mold has begun to grow on the tiles surrounding the ceiling register. And while those ceiling tiles might look bad from the outside, that type of growth is a good indication that the inside is much worse. Over time, the dust that settled in to this ductwork becomes contaminated with bacteria and fungal matter, which then becomes a food source for the mold. If untreated, the bacteria and fungi will continue to grow until it forms an almost solid layer of mold like the one that you see below.

Moldy supply air duct

Moldy Supply Air Duct

Here is what’s hiding behind that ceiling register. To the untrained eye, this looks like a strange hallway of red white and gray. But, to the dirty duct professional, that is a mold paradise. All of the gray and white that you see is mold (the red is just insulation peeking through).

Cleaned and treated supply air duct

Cleaned and Treated Supply Air Duct

So what did we do to that horror hallway of mold? First we vacuumed out the dust, then we sprayed the insulated ductwork with a sealant, which does more than just seal the insulation, it also creates an inhospitable environment for any future mold or bacteria growth. And voila! All clean!


When your building engineer or technician is changing out the air filter on your A/C unit, this is a great time to take a look into the ductwork to see if you have a mold problem beginning.  You can also monitor this yourself by watching out for any black stuff accumulating on the air vents around your building.

If your workplace exhibits any of these symptoms, The Houston Chronicle has some tips on how to report mold-related concerns to your employer. For more information regarding the impact of having mold in your office, see OSHA’s Safety and Health Information Bulletin on Mold in the Workplace.

Give us a call using the number above if you have any questions about the blog post, or need to schedule residential, commercial, or industrial work. We are happy to answer any questions you have!

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