On some interior walls in my house, I'm noticing dark patches that
seem to be appearing between studs. The walls are sheetrock that have
been painted a light color, and in several places, darkish, smokelike
color is emerging through the paint. Most of them appear high up, near
where the wall meets the ceiling. In the largest spot (about 3'
high), I can clearly make out where two studs straddle the dark area,
as if whatever is causing the darkening is trapped between the two
studs. What could be causing this discoloration?
I have to go with priming - over a lousy insulation job. As air moves
back and forth through the wall, bigger dirt particles get trapped on
the wall's surface. Only you will know if you can/should get more
insulation and a proper vapor barrier into that wall. In the interim,
I would scrub the wall and then prime the entire wall with one of the
commercial products like KILZ which advertizes it will cover anything.
Years ago (maybe still do) Glidden sold a vapor barrier paint for such
problems. Other mfgrs may.
You could get what you use tinted to match the current color if you
are enamored of it.
It makes sense it would be in this particular room. This room did
have a leak in the ceiling which has been fixed. But do I have a
bigger problem now? Will the mold go away now that the roof is fixed,
or do I have to tear apart some walls? Is mold like this typically
toxic? I have a new baby in the house and want to be sure to do
whatever I need to do quickly.
By the way, the ceiling in this room is a vaulted ceiling, so there's
not much space above it in the attic, but some.
So how would I determine whether it is indeed mold or not? Will it
actually be fuzzy black mold on the wall surface? (It's up very high
on a wall in a high-valuted room so I haven't been able to examine it
closely yet.) If it is mold, must the walls be torn out, or is there a
surface treatment I can use?
It is not all that easy to say. Based on my limited experience it has
turned out to be mold about half the time. So far I have not had any of the
deadly mold. I have had it professionally tested. Note, professional
testers associated with mold recovery companies may not offer totally
unbiased advice. A simple air test will almost always come up positive, the
stuff is in the air. One test showed "positive" but the air outside showed
about five times higher.
Usually a spray with bleach will kill it. If it is in the building
materials I suggest that they should generally be replaced.
You may want to check with your local authorities, but be aware that
doing that could, in some areas cause a lot more problems tan it solves.
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