Re: Black dust deposition

[Guest guest]

My

question is: Has anyone ever found an apparent " soot

deposition " condition (classic pattern, showing black accumulation

on ceiling at joists and nails, etc.) to be caused by dust from dried-out

closed-cell foam carpet backing?

I'm going to offer another possible reason for the soot in the carpet

other than the foam. I had one case where the carpet in the middle

of the floor has a soot pattern corresponding to the outline of an OSB

panel used for flooring. This location was on the second

floor. In this case, the builder had used a first-floor floor joist

cavity as a horizontal return duct. Usually, floor stud cavities

are used for return ducts. However, just like in those cases where

using the stud cavity a return puts the whole wall under negative

pressure, this horizontal return duct put parts of the floor under

negative pressure. Whereas negative pressure in the wall tends to

pull air under the floor edge of the wall, in this case, air was being

pulled around floor panels. I could actually release a smoke tracer

along the soot mark and watch it being pulled into the carpet.

In your case, some foams are used as filter materials and I would not

doubt that the carpet in this case would be able to filter soot out of

air being pulled through the carpet. Over years, the accumulations

could be enough to puff up when someone walked across the carpet.

The material could also be regular household dust (whatever that is)

combined with soot or other atmospheric carbon with dust to give it a

black appearance. Given the size of most carbon particles, I can

see where it would get into building material surfaces and be a pain to

clean--sounds like a sealing coating job to me.

Granted, you might not have a negative pressure situation; but I got the

chance to tell a little experience story anyway. Who knows, it

might be somebody's " aha " moment.

******************************************************

If what is written looks too stupid to be written by me, I disclaim

it. On

the other hand, if it is brilliant, then I have no one to blame but

myself.

Otherwise, whether you choose to accept my opinion is up to you.

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K. Klein, PE ME, MBA

Indoor Air Quality Solutions, Inc.

2523 SR 133

Bethel, OH 45106-0007

VOICE:

FAX: (with notice)

E-mail: mkklein68@...

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Wouldn't it be nice if common sense were really common?