As my title states, I have a house that is on a slab and the exterior and most interior walls are block and covered with plaster. Since we bought the house we have noticed a musty smell that we originally thought was the washing machine.

It wasn't.

My concern now is that is may just be the HVAC system built in the slab, but that costs thousands to clean, and to reseal with spray. The smell isn't just in the hvac system though, it seems to be seeping out of the walls. I am just looking for suggestions, ideas, or even concerns that informative people may have on this issue. Anything helps!

  • Hello, and welcome to Home Improvement. Unfortunately, tracking down odors isn't something we can do from here, and is explicitly off-topic. And, you should probably take our tour so you'll know how best to participate here. – Daniel Griscom Aug 6 '19 at 15:15
  • 1
    I'm voting to close this question as off-topic because tracking down odors isn't part of our domain. – Daniel Griscom Aug 6 '19 at 15:15

My sister had a condo and had very similar problems with the odor. It was the a.c. ducts actually installed in the ground with the foundation poured over then. They rusted out and that's where the musty smell came from. We ended up filling in the ducts and sealing them and running some new ducts on the ceiling and framing around them with drywall. If you have registers in the wall that might be why you think the odor is seeping in from them. Good luck.

  • 1
    I agree replacing the duct work inside is an option but the homes I have worked on that had this issue also had copper plumbing that was failing flat roof & slab it was cheaper and looked better to cut but I will never do that again it was a really tough job. – Ed Beal Aug 6 '19 at 19:15

I am not sure that it is off topic. Have you had the trunk lines inspected with a bore scope? A plumber can probably do this, I would be looking for standing water in the trunk lines. With enough moisture in the lines the moisture can get into your plaster and other porous surfaces. A dehumidifier or several may be needed to remove the moisture in the air and may help but if the duct work is filling with even a small amount of water cleaning and sealing or cutting and replacing is the only path forward I know of.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.