Hi there, I am hoping someone here can answer a question for me. I have a stucco house that was wrapped with Tyvek HomeWrap (propylene spun bonded olefin fabric) before the stucco was applied. I have been told that that HomeWrap is not recommended for use under cement based stucco, but I cannot get an explanation of exactly why that is.
Thanks in advance…
I hope tyvek is not the only moisture barrier you have on your home!! ASTM requires 2 layers of grade D or better behind stucco.
For more stucco Q - A go to http://www.badstucco.com
in the new forum.
Or we can chat here thats fine. Probably even better.
What part of the country are you in?
Carl
Thanks Carl and Joseph.
To answer your question Carl, unfortunately Tyvek HomeWrap is the only material under the stucco. My family and I had the house constructed in Calgary 5 years ago, and am now finding that there are several problems with the stucco. This would be one more. I am not sure that there is two layers, but judging by the other problems I have found I doubt that there are. 
I did find the thread on the badstucco.com forums on Homewrap very good though, at least I have an idea of why they don’t recommend HomeWrap under stucco.
Craig
Stucco in direct contact with any of the building papers or housewraps decreases moisture permeability and increases the capillary transference.
Therefore the must be installed need for the drainage plane second layer.
Imagine being in a tent during a rainstorm no leaks until contact is made with the tent material. Once this happens the leaks can’t be stopped until the entire system is dried again.
All housewraps go against the sheathing, under a layer of another material, not in direct contact with the stucco. Reversal of this application and you’ve wasted the money spent on housewrap because it no longer performs as intended.
If you really want the science Dr. Joe’s is the place to go. search
http://www.buildingscience.com/sitemap.htm
eyerise,
In my haste to provide an answer to your original question I forgot a very important item.
Contact the manufacture with your concerns: http://www2.dupont.com/NASApp/tyvek/RequestGateway