Bleach, vinegar, mold, help.
January 11, 2015 7:13 AM   Subscribe

I recently discovered mold in my apartment. It's a new building (a backyard cottage) and very airtight, and recent cool/rainy weather caused excessive condensation on windows...which led to black mold on windowsills. I'm about to move out, for other reasons. But I'm trying to get the mold out of one of the windowsills before I go. A few more details inside.

I think the apartment was sort of badly designed, because the windowsills are beautiful slabs of wood that look almost untreated/unsealed, and the condensation problem is ongoing (and so bad that sometimes I'm wiping up water as it rolls down the frames). But six windowsills in the apartment cleaned up with no problems. On the last one, the mold seems to be in the wood. I tried cleaning with borax and then a little bleach (I don't think bleach works well on wood). I'd like to try vinegar, but is that safe if I used bleach previously? It's been a couple of days since I tried the bleach, and I think I cleaned it all up, but there might be traces left. Any other ideas for fixing this?
posted by three_red_balloons to Home & Garden (12 answers total) 6 users marked this as a favorite
I'd call the landlord and him/her know, this is a maintenance issue. There was nothing you did to cause this, nor should it be your problem to remediate it if routine cleaning is not working. Send an email and ask the landlord how he/she would like it handled. Do this in email to document the exchange, in case the landlord tries to withhold a part of your deposit.

You can go to Home Depot, they have mold removers that are used on decking. They're pretty stinky and strong so you'd want to use on a day when you can open the window for fresh air.

But get advice and permission from the landlord first.
posted by Ruthless Bunny at 7:21 AM on January 11, 2015 [1 favorite]

I think vinegar should be safe by now. Bleach breaks down pretty quickly, IIRC. Having said that, in my experience vinegar doesn't actually work that well. If bleach doesn't do the trick, there are stronger mould killers on the market that contain disodium octaborate, but you must be very careful when using them (ventilation, eye protection, masks).

There was nothing you did to cause this

Unfortunately, the landlord may disagree. Mould from condensation is a common problem here in the UK, and the standard line among landlords and letting agents is that it is caused by tenants' "way of living" -- i.e., taking showers, boiling pots, drying laundry, even breathing. Obviously it would be ridiculous to expect tenants not to do these things, but it is frequently used as a way for landlords to pass the buck. Tenants here are often advised to leave windows open in all weather, or to wipe down walls and windows daily, and if they do not do so they may be held at least partly responsible for mould.

The OP should still tell their landlord, though, so that they will at least not be accused of concealing the problem.
posted by Perodicticus potto at 7:30 AM on January 11, 2015 [1 favorite]

Response by poster: Thanks for the answers so far- just to clarify, I did tell the landlord as soon as I noticed the problem. They asked me to try to get rid of it. I agree that it's probably technically their responsibility, and I may not try to do anything more, but I was hoping to take care of it (both to avoid any attempts to take something out of my damage deposit and because I feel bad to leave a brand-new apartment in worse condition, even if it was more a design flaw that anything I did). I'm in the Bay Area and I know in SF mold is a "legal nuisance" but I think it may be a little more of a gray area here in Oakland...
posted by three_red_balloons at 7:49 AM on January 11, 2015

Best answer: Concrobium Mold Control (Home Depot has it) works fairly well on wood (certainly better than bleach or vinegar). If the window sills are really untreated (which would be ridiculous), the mold may have penetrated quite deeply.
posted by ssg at 8:03 AM on January 11, 2015 [1 favorite]

I've had this problem as well, mainly in a bedroom where our overnight breathing condenses on the windows, and have used regular bathroom mildew removal products with reasonable success. Any black stains that go below the surface are not easy to remedy. I would try oxalic acid, which is stronger than bleach but won't lighten the wood's natural color the way an A/B wood bleach mixture will.

As a corollary question I wonder if anyone has figured out a good way to refinish such wood to resist future mold staining. I used a couple of coats of polyurethane, thinking that any future mold would just grow on its surface and be wipeable-off (wipe-offable?). But that doesn't seem to be the case. I'm wondering about oil-based sealers, instead.
posted by beagle at 8:21 AM on January 11, 2015

Best answer: I have seen this problem before. The wood needed to be sanded and treated.

Beyond that, there is something wrong with your apartment. You would do better by the the next tenant to make the landlord take care of it. Take pictures. Write a summary of your remediation attempts acting on landlord's previous request. Email to landlord. If your landlord is reasonable, that should prevent any attempts at taking money out of your deposit for this issue.
posted by zennie at 9:12 AM on January 11, 2015 [1 favorite]

I'd try Tilex bathroom cleaner, it really does very well against mold and I used to clean a poorly designed/executed in-shower windowsill with it. It soaks into nooks and crannies and obliterates mold.
posted by quince at 11:01 AM on January 11, 2015

I'm an Oakland landlord. I'd email just what you said here. ("I tried X, Y, and Z; that worked on 7 windowsills but not #8; what should I try next?") If it's truly untreated wood, you could try a fine-grit sandpaper (one with a very high number, like 300 or higher). But they might be somewhat legitimately upset about you damaging the finish or sanding down below the stain (the color treatment applied to the wood).
posted by slidell at 11:30 AM on January 11, 2015 [4 favorites]

I see a couple of options here:

1) Written correspondence of some sort documenting what you have already tried and that it worked on the other windows but not this one (and that you asked around and are being advised by some people that sanding is the next logical step) so as to try to cya and put the ball in their court as to what to do next.

2) If you are any good with things like sanding and then making it look right afterwards, you could try to fix it yourself in hopes you can fix it on the cheap without them calling in a professional and/or replacing the window.
posted by Michele in California at 1:33 PM on January 11, 2015

We used sugar soap to clean up old mold spots on a wooden painted beam in our ceiling and it worked well.
posted by dil.emma at 4:23 PM on January 11, 2015

Beagle: have you tried spar varnish? It's for very harsh environments; it's used on boats. Very good for repelling water, salt, and light. Surely mold too?
posted by kestrel251 at 8:05 PM on January 11, 2015 [1 favorite]

Depending on your state (washington for example) you might actually be responsible for preventing mold and/or the damaged caused by condensation issues. If it's still a problem, getting a dehumidifier will help but if you feel you won't be there long enough to get one, then you need to, at minimum, wipe off any water or condensation as in occurs.
Being too well sealed can actually be part of the problem! Water use in the house and your own breathing creates moisture and if it's too well sealed that moisture has no where to go but to cling to windows and walls.
Mildew and mold can stain. Depending on how deep the stain is, you might be able to sand it off?

Follow guidelines for cleaning found here: Or here Mold cleaning can release lots of spores even from dead mold and make you sick so you'll want to at least pick up a face mask.
posted by HMSSM at 9:20 PM on January 11, 2015 [2 favorites]

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