I have a couple of questions, first to protect the OSB on my addition I covered the exterior in tyvek ( don’t hate me). What I want to know is when I stucco in the spring can I cover the tyvek with tar paper instead of ripping it off. They use to put two layers of tar paper. Nex question, they make mold resistant OSB and drywall can you buy the stuff to coat the wood and do it yourself. I want to coat the stud cavities before I insulate. It is probably overkill but it would give me piece of mind.
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There is a product called "TIMBOR" a borate powder you put in solution and spray.
It's a pest control product listed as a fungicide.
Can be had cheaply from "Doityourselfpestcontrol" (Google...) sites on line.
Have at it.
I believe two layers of felt over tyvek is an excellent detail for stucco.
k
The mold resistant drywall has a synthetic (fiberglass) outer layer rather than traditional paper.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
"The mold resistant drywall has a synthetic (fiberglass) outer layer rather than traditional paper."Except that kind that has paper on it.http://www.getmoldfacts.com/moldtough/index.jsp"Sheetrock¯ brand Mold tough™ gypsum panels have a noncombustible, moisture- and mold-resistant gypsum
core that is encased in moisture- and mold-resistant, 100 percent recycled green face and brown back papers.
The panels feature tapered long edges for easy finishing"
.
William the Geezer, the sequel to Billy the Kid - Shoe
There is no reason you can't treat the OSB yourself. Anything you do will improve it.
Since it's under vapor barrier(s) and siding, you could use latex, but it is porous and breaths. The advantage of this is you can pick up high end miss-mixes for a a dollar to five dollars a gallon. This isn't an exterior paint job, so you are horribly concerned about priming. I've painted houses this way (though I did prime those). I brought all the paint home (I used pale/pastel colors) and mixed them in a large garbage can. You get a nice gray).
A better option is pick up the oil based paints, the soak in because they dry slower.
Finally, you can just oil the wood. If you want the finish to harden, add about 30% Varithane or its equivalent (the oil based, not the waterborne type). It won't get as hard as Varithane, but it's not a wear surface and a little flex in this situation is good.
If you really want to crank things up, buy bulk borax (e.g. Twenty Mule Team) and dissolve it in water, then spray it on your wood. As long as the wood will not be subjected to running water, it won't wash away. Wood treated with borax is used to keep carpenter ants and termites at bay and it works darn well. Let it dry well before oiling or painting and you're off and running.
If your going to use synthetic stucco - its far more important to be sure all of the installation details are rigorously followed than to be worried about mold-proofing the OSB (which is a different product from plywood, FWIW)
"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."
Howard Thurman
So you're planning to have enough moisture in the wall so mold will grow on the OSB? ;-)
In addition to the TIMBOR the previous poster noted, there is another similar product called BoraCare.
I'm not a stucco guy but Dupont makes a product called StuccoWrap to use vs. Tyvek under stucco.
John
J.R. Lazaro Builders, Inc.
Indianapolis, In.
“You can either wait for the storm to pass, or you can learn to dance in the rain.”
"I'll be long gone before some smart person ever figures out what happened inside this Oval Office."—Washington, D.C., May 12, 2008
I've used Stuccowrap a couple of times on Stucco applications. It looks like concertina'd Tyvek and helps with drainage. Both times I've used it has been on the Durock and TEIFS NuTech Stucco Wall System which has been very successful for us.
Plywood sheathing > Stuccowrap > Durock > Base Coat > Mesh > Finish Coat.
It would not hurt at all to treat the OSB yourself. There is always moisture present, even if the wall is not letting in any rain / snow / ice moisture.
In the JLC Guide to Moisture Control, Joe Lstiburek does some interesting tests with Tyvek StuccoWrap, and finds that it performs best if it has a layer of felt between it and the stucco. Otherwise, the scratch coat adheres to it and pretty much negates the wrinkle-drainage plane.
k
Edit- actually, upon re-reading, I see your method puts the durock between the stucco and the wrap. That seems like it would probably keep the wrinkles open for drainage... might be a very good hybrid.
Edited 1/16/2009 1:33 am ET by KFC
Every building store I tried doesn't carry the stuccowrap and they looked at me as if I was nuts when I asked for it and rather that argue the point with them I chose to put regular tyvek on to protect the OSB. Because I have the regular tyvek on I figured I would put tar paper over it. That is all the code requires is 1 layer of tar paper. Onto the second question I want to prevent mold from growing in the stud cavities. OSB seems to make a good petri dish for mold more so than plywood. Any small hole in the vapor barrier in the wall will let alot of moisture in the walls and combined with the sponge like quality of insulation you just asking for problems. I have moved a few things around the house I am in and I notice a small amount of mold where electrical boxes are, the wires have been sealed with acoustical sealant. Not enough mold to call the haz mat team but I would rather be safe than sorry.
good petri dish for mold more so than plywood
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