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camdunning 05-11-2013 08:00 PM

Leaking furnace exhaust creates musty smell in walls?
Hi - new to this forum but I was hoping someone might be able to help me out. I bought my first house a year or so ago, and one room has always smelled a little musty. The smell kept getting worse, so I got overly ambitious today and opened up two of the walls to see whats going on. I don't see any mold really, but the smell is pretty strong inside the walls.

To jump forward a few steps, I figured out that the exhaust pipe from my furnace was rusted out underneath the house, and had been dumping the exhaust directly underneath the house right around where one of the the walls is for this room. The insulation above the vent was soaking wet when I went underneath to check and there are a few holes in the subflooring for pipes and such, so I'm guessing that's how the moisture came through into the walls.

My question is, if I can't see any obvious mold on the studs or subflooring, can I just let everything air out and dry and then re-sheetrock the room? Or do I need to take more serious steps to track down any mold that would be hiding in the studs or subflooring? I'm not very handy so I'd like to avoid that if possible Either way I've turned off the furnace and will be fixing the exhaust asap.

Thanks for the help!

user1007 05-11-2013 08:37 PM

I would first be worried about carbon monoxide getting into that room if the system had a busted exhaust system. You might think about adding carbon monoxide detectors because you may have dodged a bullet on this one.

The moisture may be from condensation and may go away. However, if the integrity of the plaster or drywall has been compromised you really should replace it. You should abate any mold or mildew.

camdunning 05-11-2013 10:06 PM

Thanks sdsester. I do think I dodged a bullet on this one with carbon monoxide. I pulled out most of the old drywall and didn't see much or any signs of mold, but the room still smells very musty so I'm worried that mold may be in the studs or the subflooring and I just can't see it. I was thinking about giving it a few days to dry out (now that the furnace is off) to see what happens with the smell, but I don't want to put up new drywall and then have the mold come right back and have to pull everything off again.

REP 05-12-2013 12:23 AM

Mold can only exhist in warm damp places.Fix the vent first ,replace the insulation and you should be good to go.

wkearney99 05-12-2013 01:23 AM

Given the downside of mold growing and ruining anything new you put in there, I'd certainly consider having an air test done to see what's present, then decide.

Seattle2k 05-12-2013 01:47 AM

One of the products of natural gas combustion is water vapor.

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