My new house is framed and the roof is papered . Im just starting the facia and sofit work so the roof can go on. I’m trying to do some research on the next phase I’ll encounter that I’m not sure about which is the age old building wrap dilema . I bought a couple rolls of dow styrene wrap which I used around the upper gables and dormers since i was up there already . I have since tested it and found the results disturbing . I filled a mason jar half way with water , marked the level , and covered the top with the dow wrap secured around the neck with rubber bands . After 2 wks. in the sun I noticed no evaporation . I tryed the same with Typar got similar results . I thought this stuff was suposed to be permeable to vapor . Any insight out there ?. I may just have to use 15lb. felt .
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Greetings c,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
When I build my house I will use 30# felt. It is proven and the cheapest of all. I once replaced a bunch of windows on a house about 12 years old. It was Tyvek under cedar clapboards. The Tyvek was deteriorated to the consistancy of tissue paper. I really think the whole house wrap thing is a huge marketing rip off. Go with the felt and it will work fine if you detail it correctly. Good luck.
Mike
uh oh!
snort, you just opened Pandora's box and let Medusa's head out.
I jus calls em as I sees em
Is there any chance you took some photo shots of the old tyvex you could post here?
no, I didn't take any pics, it was a good 4 or 5 years ago. Wish I had though.
Thanks for the info on your experience . I probably will go to the felt option . countus
Your comment that you may revert to felt implies you think it is more permeable than the synthetic wraps, but without testing, you're just guessing. Test the felt the same way - obviously the rubberband technique wont work, but you could caulk the felt to the opening.
The underlying question is if the water-in-a-mason-jar test is even an effective test of the performance of the wrap on a house. If the wrap doesn't allow visible drop in water levels in your mason jar, does that mean it's no good? If it does alow the water to visibly drop, does that mean it's good?
Felt versus Tyvek/Typar is nearly a religious debate with passionate advocates for both. However, I think there are more sophisticated tests available to assess the measure of both.
I remember reading somewhere that felt is more permeable than the housewraps . I'll have to spend some time digging through my resources . i don't see anything wrong with the mason jar test , If anything there would have been error favoring evaporation if the rubber band seal wasn't adequate . Thank's for your input . Countus
Rerun but still good information.
http://tinyurl.com/2268w
Google up "VaproShield."
They have several building envelope products including door and window wraps, roofing paper, and wall wraps.
It's expensive stuff, but I love it. I have used only their window and door systems, but am completely confident that I'll never have moisture infiltration in those area.
The website contrasts their product to most common wraps [Tyvek, Typar, etc.] and rates both evaporation and permeability. It's really more like GoreTex than anything else I can compare it to. Not suitable for all roofing products [no metal] but well worth a visit.
Good luck
Tarpaper seems to work well
tyvek is a solution looking for a problem.
The natural tannins in cedar will erode tyveck quickly. When using cedar one should use tarpaper.
Well, that is another reason not to use the stuff .I guess I'll just use it to make kite's , it works great for that . thanks , countus
But I think its a better job under vinyl or hardi board. One reason is the easy install ,( bigger rolls) which creates less seams at the same time. But you can't argue with tar paper. It has stood the test of time and proven itself worthy. Its also cheaper!