When we moved some furniture in a bedroom, we noticed black mold on an outside wall. We susect that there is no insulation between the sheet rock and the exterior walls. We live in the Richmond Va. area which is subject to temperture changes. Anyone know what we can do before we open all walls?

You may not have any option other than to open the suspected moldy walls. If you are showing mold on the living side, then odds are that there is even more mold inside the wall cavity.

Still, I would first inspect the exterior of the area. Look for roofing damage or questionable flashing, damaged siding, window flashing - basically anything from the outside that would be the cause of water leaking inside.

It's also possible to have an extreme case of mold caused by an always shaded side of the house.

Amscott6:

I wouldn't do a thing unless and until I have more evidence than just mildew growing on the wall that there's a problem with the insulation in the wall.

I've seen this situation in closets where there was no source of heat and no air circulation. The problem is that you have heat loss through the exterior wall, but no source of heat (such as air circulation) behind the furniture. The result is that the wall gets cold, condensation forms on it, and mildew grows on that moisture.

Do this: Clean the mildew off with some bleach diluted with 10 parts water and them just move the furniture a few inches away from the wall, and that should solve the problem. Check occasionally with a flashlight, but chances are that the source of the cold (and hence condensation and hence mildew) was the lack of warm air circulation behind the furniture.

If push comes to shove, you can always paint that area with a paint meant for bathrooms like Zinsser's PermaWhite Bathroom paint (available at Home Depot and other fine retail stores) to prevent mildew growth on that area of the wall. Bathroom paint will have a mildewcide in it that kills mildew spores before they have a chance to grow into mildew fungii, thereby keeping your wall mildew free. But my guess is that you just need to provide for better air circulation, and the problem will disappear.

This message has been edited. Last edited by: Nestor,

Check some cheap things first.

Lack of air flow in a room, reasons for it, no gap under the door for return air flow. Furniture up tight againt a wall.

Air leaks around a window causing condinsation.

Plugged up gutters causing water to get up under the shingles and soffits.

Lack of insulation or poor insulation.

Lack of soffit venting or it's covered up with insulation in the attic. Also no ridge vents.
Lack of vaper barrier on the ground if there's a crawl space.

Standing water under the house.

Mold is only form in wet place or thing. Outside wall wets more than inner walls. So make sure that your wall is well plastered, So that it will not sink water and your wall remain dry and hence mold will not form. If mold have formed previously then spray vinegar on it let it sit for 1-2 hours then wash it with clean water and scrub it with sponge. It will definitely help in removing mold.



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Has anyone else tried marvin_smith's suggestion to use vinegar to remove mold? That's the first time I've ever heard vinegar suggested as being effective on mold.

He's suggested vinegar for everything.
It is a mild acid, give it a try. It's not going to hurt anything but any living plants or grass below where you use it.
I use bleach, it's fast and cheap if you pick it up at the dollar store.

This message has been edited. Last edited by: joecaption,

IMHO, marv is just trolling to push his links.

This message has been edited. Last edited by: Jaybee,

Jaybee is right; MarvinSmith doesn't really address specific issues but rather pushes a generally standard "solution", with a link (on which I would never click) to what I suspect is some product or services he's hawking.

That having been said,

SturdyNail, I've used baking soda and salt in a water base to remove mold from bathroom tile, and it was very effective (somewhat to my surprise). I have used white vinegar for mold removal on kitchen utensils and toothbrushes.

White vinegar has a lot of uses in cleaning, and it may be that it is effective on mold.

And a comment on mold on exterior walls...
I've had this problem in my house, and although I know there are more serious issues, which unfortunately I can't afford to address, I just scrubbed the walls down at the end of high humidity seasons. It wasn't black mold, just the yellowish type stuff that seems in my house to develop where there's excess moisture and no ventilation (such as the basement areas when the dehumidifier is on the other side of the basement) and the summer humidity is very high.

I think I've written before that a now deceased neighbor, who was one of the first residents in this sub, said that the area on which my house was built was a swamp when he moved in. Apparently it was never properly filled in and the houses in this area suffer from high levels of moisture.

Amscott, how much mold is there and how bad is it? Is it solid, growing up the walls for a few inches, several inches, or several feet? Is it on a north wall? Is there any mold growing on the back of the furniture which was close to the wall?

I use white vinegar, 3% (regular pharmacy) hydrogen peroxide, for mold removing.

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This message has been edited. Last edited by: kristoffersava,

Nestor is right on. That is the perfect solution. I don't think you will have any issues. Now if you start to have mushrooms growing out of your walls...then that's a horse of another color.