# Drywall: How much humidity can it take?



## SeniorSitizen (Sep 10, 2012)

KarenRei said:


> Hey - so I'm new here and have a bit of an odd question. I grow tropical fruit plants in my apartment in Iceland (I've got ~5 meter ceilings in my plant room, it's converted industrial space). One persistent problem to indoor growers is spider mites - almost-invisible plant-eating spider relatives so small that they eat a single plant cell at a time. They're virtually impossible to eradicate by conventional means without turning your plants into a toxic mess, and they'll always come back. But they have one easy natural enemy: humidity.
> 
> The problem is, I know from past experience, high long-term humidity and drywall are a recipe for mildew. I don't have to worry about the floor (concrete) or the ceiling (some sort of synthetic plasticy panels), but I believe the walls are drywall (hmm, should probably make sure - is there an easy way to test? The building's structural material is concrete but I was at least able to drill into the interior walls to attach screws... whatever it is, it's painted)
> 
> ...



Just off the top of my head, or what remains of it, mildew resistant paint or mildew resistant drywall ( not green board ) over your ??? drywall ( sealed from your drywall ) may be a couple of options.

As for moisture content, 13 percent + by weight is considered where organic material begins to become questionable. To monitor that a moisture meter may be of benefit. As to length of time to satisfy both spider mite and mildew deterrent, I suspect that would need to be tested by you. If you discover the formula maybe you could get published.:thumbup:


----------



## ToolSeeker (Sep 19, 2012)

I live in fla. the humidity here in the summer is high and they use a lot of drywall outside in like fla. rooms. This will probably not help you since your drywall is already installed but maybe. The mold on drywall is feeding on the paper, they now have a paperless drywall. Mold will also feed on joint compound, the answer there is to use Dura bond. If you paint with a good quality paint applied heavy and 2 coats it should protect the drywall as the moisture will be on top and can't soak in, and ask the paint store to put a mildeside in the paint.


----------



## KarenRei (Sep 7, 2013)

Hmm, is there maybe a clear spray-on coat one could apply to resist moisture? I'd hate to ruin the professionally-done paint job with my amateur mucking-about


----------



## Gary in WA (Mar 11, 2009)

Welcome to the forum!

http://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers

http://www.google.com/url?sa=t&rct=...h4HQAg&usg=AFQjCNEevGULCZz10RNeemu4HHePjOl5pw

http://www.mde.com/publications/Jan07News.pdf

http://www.fpl.fs.fed.us/documnts/fplrp/fplrp319.pdf

Just "Google" the spray v.b.; http://ths.gardenweb.com//forums/load/build/msg112224319360.html?8

Gary


----------



## jburchill (Oct 3, 2010)

Fairview said:


> Just off the top of my head, or what remains of it, mildew resistant paint or mildew resistant drywall ( not green board ) over your ??? drywall ( sealed from your drywall ) may be a couple of options.
> 
> As for moisture content, 13 percent + by weight is considered where organic material begins to become questionable. To monitor that a moisture meter may be of benefit. As to length of time to satisfy both spider mite and mildew deterrent, I suspect that would need to be tested by you. If you discover the formula maybe you could get published.:thumbup:


 
Why do you say not Green Board? Shouldn't it be recommended, sinces its moisture resistent? Resist moisture and mold/mildew would be harder for it to grow on.


----------



## SeniorSitizen (Sep 10, 2012)

jburchill said:


> Why do you say not Green Board? Shouldn't it be recommended, sinces its moisture resistent? Resist moisture and mold/mildew would be harder for it to grow on.


Greenboard doesn't have paperless backing and is rated moisture resistant not mold resistant. I'm just saying there are better products available. Below info. is copied from HD page and more information is there.
************************************************

Mold resistant board products
offered include USG
(MoldTough), 
National Gypsum (XP) and
American Gypsum (M-Bloc)
• Use paperless backing and
special coating to prevent mold
from growing


----------

