Folks here in So. Vt. leave their Tyvek exposed sometimes for years. How long is it effective, how long can I wait to put up the white cedar shingles?
Join some of the most experienced and recognized building professionals for two days of presentations, panel discussions, networking, and more.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
It's not good one day and bad the next. It slowly degrades, and the rate of degradation is controlled by sun, rain, wind, and probably two or three other things.
I forget what Tyvek specs, but I think it's like 60 days. That's probably a good lower limit, but one could go longer if conditions aren't terribly bad. Otherwise there are other brands of wraps that claim to be able to last longer.
(But I'd say about 6 months is the upper limit on Tyvek, before it should be ripped off and replaced prior to final siding. It is effective longer as a temporary covering, though.)
You can actually just install a new layer of housewrap right over the old one - no need to rip down and replace.Justin Fink - FHB Editorial
"Everybody wants to know what I’m on...
What I'm on? I’m on my bike, busting my ### 6 hours a day…
...What are you on?"
- Lance Armstrong
The tannins in cedar degrade Tyvek so tarpaper is the right underlayment for cedar shingles.
According to some, the tyvek will only last 5-10 years in direct contact with ceda
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
That bit of wisdom has been hotly debated here. IIRC, the Tyvek people don't admit to a problem, and the reports of problems have been spotty.
If your view never changes you're following the wrong leader
DuPont warns in their literature that the "wettability" of Tyvek and building papers can be increased by chemical surface contaminants (surfactants) although it says cedar doesn't contain anything that would do this to Tyvek. Independent testing has shown just the opposite. Typar is less affected and Tyvek is said to be reformulated to reduce this problem. If you are still concerned about it the best solution is to back prime/stain the cedar as recommended by the WRCLA and DuPont or provide an air gap.DuPont says to not allow Tyvek to be exposed to UV rays for more than 120 days. If in doubt about weathered Tyvek, you can send a sample to DuPont to see if it is still usable.
And 121 days later they'll reply.
If your view never changes you're following the wrong leader
Piffin
We are working on a lake house right now that had cedar siding on tyvek. The place was built in 1989 and had cedar dutch lap sidding so there was a full contact between the sidding and the tyvek.
We tore all the sidding off the place, were giving it a complete face lift, but the tyvek was in about as original condition as possible and I dont have any idea how long the stuff had been exposed to the sun/elements before they got it covered.
I dont know to much about tyvek, dont use it much in cabinetry anymore! But, I see where it is supposed to go to shid under cedar and in this one instance the tvvek has done OK.
Doug
Yeah, I have not seen this myself. Only read it here. There was one account from a guy who said that after ten years when he tore into a wall for an addition or something, the Tyvek was all but gone and in little pieces. I have used backprimned over Tyvek n ddon't lose sleep over it.But I like people to be aware
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I belive the mfg literature says not to expose Tyvek for more than 90 days. Typar as a better choice for housewrap if it is to be left exposed.
As far as housewrap degrading under cedar, to me, the judge is still out. I think it was those U of Mas building science guys who came up with that, but IIRC a lot of their testing is simulated in a lab rather based on actual field rear offs, etc.
Check out this article: http://www.umass.edu/bmatwt/publications/articles/housewraps_feltpaper_weather_penetration_barriers.html
Notice the date. I'm not sure if any new research has been published siince then to support the degradation of house wrap by cedar tannins (sp?). Anyone got a resource?
There would be no reason to expect Tyvek to have deteriorated behind cedar and the sheathing would not have deteriorated unless water penetrated the shingles and the housewrap.I have never seen any evidence that Tyvek is physically damaged by contact with cedar or anything else although cement stucco will adhere to it and staples can tear it. On the whole, it is an amazingly tough material. Certain surfactants (surface contaminants), similar to soap, can reduce the surface tension of water which can allow it to pass through membranes more easily but these chemicals don't necessarily damage the membrane. Spunbonded olefin wraps (Typar after 2003 and Tyvek), and building felts become slightly less waterproof when exposed to surfactants like the oils from cedar. When a virtually waterproof housewrap material leaks slightly it is can be considered significant but since building felt is already far less waterproof than the spunbonded wraps, the reduction is usually ignored. There is a different standard because the materials perform completely differently.The major difference between these WRB materials is that the spunbonded olefin wraps are effectively waterproof, the perforated wraps are less waterproof, and building felt is even less waterproof but becomes highly vapor permeable when it is wet. Most proponents of building felt seem to believe that water that gets behind it can dry to the outside more easily than from behind plastic housewraps. Most proponents of plastic housewraps seem to believe that water will not get behind the wraps if they are properly installed. So, it's a tough call. Probably the best argument for building felt is that it that Tyvek is rarely installed according to DuPont's instructions or even with much common sense. In my experience most carpenters put it up like building felt and prefer it because it is faster and easier to install. Conventional detailing of light wood frame construction has become a nightmare with materials substituted without much attention paid to their different characteristics, compatibilities or interfacing. The future of WRB's will inevitably be liquid applied vapor permeable acrylic membranes that eliminate the space where trapped moisture can cause trouble in insulated wood framing. Huber has introduced their ZIP sheathing and other manufacturers offer liquids that can be rolled or sprayed on in the field over reinforced joints and into openings. It's only a matter of time before the manufacturers of these materials wake up and jump into the house building market. Someday people will laugh when they find that a house was wrapped with the stuff they make large mailing envelopes out of. "What were they thinking?"
We had this issue come up on a commercial building and we got a written response from Dupont that the commercial style Tyvek can be left exposed to 9 monts.
"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
newfaner,
House wrap is not considered as "siding" ? :}
northeastvt(Vermont)
Ja, ya'd dink it vas ziding around here. Seen some houses done in the stuff for 3-4 years.
If your view never changes you're following the wrong leader