Moldy, Musty smell in the drywall?

AZBaobab

Hey all! After a couple years google-searching answers to all sorts of fun project questions, and getting sent here time and again, I've decided to bite the bullet and sign up.

Well, that and I have a question I haven't been able to find an answer to yet...

Re-doing a bathroom.
There's been a musty, moldy smell coming from the vanity for quite a while. I had my wife sniff around, and it was definately from the vanity, not the toilet or shower.

So, I ripped it out (along with the shower, toilet, tile, etc).



The problem is that the smell is still there, and coming from the wall/drywall behind where the vanity was.

The underside of the vanity floorboard did have some nice, fuzzy green mold growing in it (I'll get some pics up as soon as photobucket begins behaving), so that went en-mass.



There's also some water "damage" to the drywall in the form of streaking where water must have dribbled down in the past, but paper separation from the plaster itself is relatively localized.




But the smell is still there. With the wife fully assuring me that the smell is worse than ever, I cut out a chunk of drywall under the drain, and there is what appears to be water-spotting on the paper, but I've got the same spotting on drywall elsewhere in the house.



Water Spotting (?)



Same spotting elsewhere...

There's no moisture down there, the wood is nice and dry, no leaking in the pipes...

So the question is: can that moldy, musty smell embed itself in the drywall and give the impression (smell) that there's still mold, even though it's all been removed?
And if so, would just giving the B-room a nice coat of Kilz be enough to block it out?
Or, since I'm still smelling it (even with the original(?) source removed), should I keep ripping into the wall to look further?

Thanks!

Maintenance 6

It certainly doesn't look like the drywall was affected to any degree. Have you ruled out any moisture issue at the floor level? Could moisture have wicked back under the finish floor and is now causing the odor? It looks like you have the comode laying on it's side. You have the flange covered, so you don't have any sewer odor coming into the space, right? Finally, you've ruled out any issue from the shower/bath tub walls? If so, then, I'd coat it with a stain blocker and see what happens.............. or smell what happens.

AZBaobab

Thanks for the reply! I was starting to get worried...

On moisture wicking back under the floor: we're on a concrete slab (and a VERY thick one at that: ~1 foot) I've checked out the base-plate all the way around, and the wood is nice and dry: no rot there that I could see.

Yup, I pulled the porcelain throne, and fully ducktaped over the flange there (as well as cleaning the old wax off the base of the commode itself: NASTY!), sealing it off, as well as the pipe coming up from the shower trap. No, we've ruled those out as sources of the smell: it's definitely a mold/must smell, rather than a sewage smell and by getting down on hands-and-knees, we can definitely say it's coming from the wall, rather than any of the more obvious sources.

As to the shower: it was a fiberglass shell/drop in unit. It's been fully hacked up/thrown out. The pic I took of the other spotting issue was behind where the cabin was. No odor back there, and everything is dry and tight as it should be.
It's weird: the smell is most definitely coming from the wall behind the vanity and the only thing on the other side of the wall is a clean-smelling clothes closet.

I don't mind just throwing a coat of sealer on the wall and calling it good, but the wife is sort of paranoid about the mold idea, so as I don't have that much experience with mold myself (moved here to northern VA from Phoenix) I just want to try to rule out any possible more serious issues, rather than covering up something that may come back to bite me later on.

Thanks!
I'm guessing we'll call in some abatement people to do some air testing before I just start throwing air-freshener at it.

Maintenance 6

Drywall is pretty porous and can absorb odors pretty readily. If you have no evidence of moisture, then you likely don't have a mold problem. You have to have moisture to have mold. I have smelled the same musty odor in old drywall in areas that had no problems. Don't call in abatement people to do air testing. Call in an environmental testing company if you must and be sure they have the proper equipment for mold sampling and have an association with a lab that can process mold tests. Since you've already begun demo work, a simple airborne spore test may not work. You have a lot of debris in the air that could skew the test results. My opinion from what you've shown and said is that you don't have a problem since the vanity was removed. It may be cheaper to remove the bottom 4 feet of drywall and replace it, rather than incurr the expense of a full fledged airborne mold sampling test.

Maintenance 6

P.S. There is a lot of media hype out there about "Toxic Mold". Don't beleive what you read on Chicken Little web sites. Do some real research and then tell me how many people you find that died from exposure to common molds.

joecaption

Been on the roof and checked the condition of the seal around the sewer vent pipe?

Dean CRCNA

Odds are ... you have mold ... you just haven't found it yet (or the right spot).

I confirm mold problem by doing an air test and by looking at spore count. Then I use borescope camera. Not sure I trust the nose as a locating device

Zippo2

You can resolve the problem by painting the bathroom and adding the paint additive air-renu. Permanent solution for odors.