Black and white areas on old floor joists?

[matt wicson]

Hi all,

My house was built about 1950 and has these areas of white and black splotches on several of the joists. Is this expected or something harmful? Thanks so much.

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[Matt Bezanson]

Hi all,

My house was built about 1950 and has these areas of white and black splotches on several of the joists. Is this expected or something harmful? Thanks so much.



Likely to be some type of mold. How harmful is a very open question. Try shining a bright light almost parallel to the surface. Mold will stand out from the surface, discoloration that's native to the lumber won't.

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Hi all,

My house was built about 1950 and has these areas of white and black splotches on several of the joists. Is this expected or something harmful? Thanks so much.



Likely to be some type of mold. How harmful is a very open question. Try shining a bright light almost parallel to the surface. Mold will stand out from the surface, discoloration that's native to the lumber won't.

[John Kogel]

Hi all,

My house was built about 1950 and has these areas of white and black splotches on several of the joists. Is this expected or something harmful? Thanks so much.

Is it expected in a 65 years old house? Yes, a bit of dirt, soot, mould or all three.
Is it harmful? It is not hurting the wood. Dampness could be harmful so make sure the basement stays dry. If you do laundry down there it needs some ventilation, or heat or both.
Harmful to occupants? Not likely. I don't see anything I'd worry about in those pics. If you spend a lot of time in the basement, why not paint the wood?

[Mike Larmon]

Looks like dried up mud and condensation stains. no big deal.

[Lon Henderson]

Looks like dried up mud and condensation stains. no big deal.
Looks more like stains than mold to me, too. If lumber lies around for a while out in the weather before being used, it can look beat up. But having samples evaluated is the only way to know.

[Mike Larmon]

Testing has little value as mold is everywhere, most samples test positive and there are no standards for acceptable levels. Of course theres mold there, but If you see it or smell it, get to getting rid of it. Otherwise if it's not posing a problem, then don't worry about it. Don't confuse yourself with ambiguous test results. further, in some states such as illinois you have to disclose if the house has been tested for a real estate transaction. This puts you in a very costly jackpot for a house you are leaving, all much ado over nothing.

[Raymond Wand]

Was a moisture meter used? That would indicate if the wood has elevated moisture to support mould growth.

[matt wicson]

Thanks for all the replies. The black marks appear to be in the wood, not growing above the surface. Ill likely have an home sellers inspection in a few weeks and will post again if it turns out otherwise.

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Thanks for all the replies. The black marks appear to be in the wood, not growing above the surface. Ill likely have an home sellers inspection in a few weeks and will post again if it turns out otherwise.