Re: Theroretical Drywall Question?

[Guest guest]

Todd,

You ask some very good questions and make an astute

observation about all this seeming " just...well... goofy. "

As for paper on drywall, one expert in our industry puts it this way.

" Even the three little pigs never built a house out of paper. "

The fact you don't see mold growth on the paper-backed drywall

in you humid attic is because the wetting rates are lower than the

drying rates, keeping the materials dry enough overall to not grow

mold. Building science, the materials, and the science of airborne

moisture (humidity and dew point) are complex disciplines

involving dynamic and complex situations.

Sometimes mold grows and sometimes it doesn't. It depends on

both the overall and the specific conditions actually present,

whether they can be measured or not. The mold and bacteria

don't read lab reports to decide if they are going to have an orgy

and create lots of babies. If the conditions are right for long

enough and enough times, just like iresponsible teenagers, they

will.

You question about the 1/8 inch of discoloration at the seams is

one that is appropriate for answering by -- hold on to your hats all

you long timers that know me views on mold sampling -- mold

sampling.

A tape lift of the discolored material (it may be dust) AND a tape

lift a couple of inches away from it could be sent to an accredited

lab. You will probably find some mold on each. So the

comparison is important. If air moves through the crack and the

material is otherwise dry, it is likely dust. If it is ELEVATED mold,

however, you have a moisture problem to address that is just as

important as the mold growth.

Carl Grimes

Healthy Habitats LLC

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> Our house has a drywall ceiling with blown-in insulation above it.

> The attic space is " exposed " through sophet vents and a ridge vent,

> to all the vissitudes of humidity and temperature of the great

> outdoors

> of humid East Tennessee. For that matter, so is the drywall in our

> unheated garage.

>

> At any rate, I often sit here and look at the ceiling sometimes,

> wondering,

> " Paperbacked drywall, why doesn't it mold? How STUPID would you

> have to be to build a house design like this? " I have pulled back

> the

> blown in fiberglass insulation in the attic to examine the drywall

> underneath, and it appears to be in fine shape. I am puzzled by

> this.

>

> And yet, I noticed particularly at some of the joining edges, where

> the

> ceiling meets a wall. The ceiling drywall can be a bit discolored

> for about

> 1/8th of an inch out all along the joint. I do not know what this

> represents?

>

> So, generally speaking, how prone is drywall in a ceiling with blown

> in insulation,

> sophet vents and ridge vent, to mold intrusion? Doesn't just plain

> humidity and heat

> over the years penetrate the drywall and foster mold? The topside

> looks fine.

> Most everything looks fine in the living space side. But the whole

> system seems

> just...well... goofy. Should I be worried? (:-/

>

> Todd in Tenn.

>

>

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