Tyvek under a Standing Seam Metal Roof?

tim fox
7/19/2007
Is it recommended to put a vapor barrier (like Tyvek Housewrap) on the rafters or roof decking to prevent moisture buildup or infiltration? Thanks
Todd Miller
Isaiah Industries, Inc.
7/20/2007
There are specific underlayments available for this. I would use one of them rather than a housewrap.
Guest User
8/6/2007
Hello, I just stripped off my roof shingles completely, and replaced all of the rotted wood with 3/4 plywood. Now, I want to make the roof water/weatherproof until I decide of the best metal roof product. I have read that Tyvek should be put down immediately, and then rolled roofing. If you know of another, more effiecient way, I would like to know. I live in the NYC area, and we have gotten more rain than ever before. Our snowfalls are sometimes record breaking also. I know that Tyvek breathes, and therefore does NOT help in the growing of mold and fungus. Rolled roofing paper on the other hand does. I believe that I should put down Tyvek, and then rolled roofing. Please give me an exact answer, since I am waiting out the storm we are having right now, and will do it myself at the next hot, sunny day. Thank you
Todd Miller
Isaiah Industries, Inc.
8/6/2007
The problem with a breathable membrane like Tyvek is that, when used as part of a tight "sandwich" in a roofing system, the same holes in Tyvek that are designed to allow water vapor to pass will also allow water molecules to pass. Not good. In normal construction, attics need to be well vented for breathability. If venting cannot be achieved then consider spraying the bottom side of the roof deck with an insulation like icynene. Some of the newer synthetic underlayments are Titanium, SharkSkin, and RoofTopGuard.
Guest User
11/10/2007
Todd, your explaination of Tyvek was incorrect. Tvek does not have any "holes" that would allow water molecule through. Tyvek is a weaved product that is weaved tight enough not to let water molecules throught but not so tight that air cannot pass. the only minus against Tyvek on a roof deck is the surface is very slippery and dangersous to walk on.
Todd Miller
Isaiah Industries, Inc.
11/10/2007
Thank you for the clarification.
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