Theroretical Drywall Question?

[Guest guest]

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.