Need to replace 3 or 4 courses of old cedar claps on my 1939 cape. There is old tar paper underneath (15 lb?) and it’s pretty torn up. Is is OK to replace it with the same thing? Or should I use rosin paper or Tyvek?
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tarpaper
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use 15lb felt, cedar will eat up tyvek pretty quick, rendering it useless. Let the tarpaper hang over the bottom course to within 1/4" of the reveal.
Edited 9/10/2005 9:07 pm ET by Demon
use 15lb felt, cedar will eat up tyvek pretty quick, rendering it useless.
Just curious as to if you have proof of this.
This topic is brought up a lot and every single house out here in NJ uses tyvek and installs cedar right over it primed or unprimed. WheneverI tell someone about what I read here or on other forums they have never heard of this.
I have sided houses 20 years ago over tyvek and when I drive past them til this day the same siding is there. I even called a rep up about 2 years ago from the Western Red Cedar Asssocaition and he said it wasn't true. They did studies on it.
I'm just curious as to how many people have proof of this. Every lumber yard I talk to have never heard of this.
Now I don't remember what the rep said about un primed cedar but I'm sure I asked. I'm just saying that over the past 20 years there are alot of house that I framed and sided with cedar clapboards and shigles over tyvek and there still there and never heard of any complaints from any builders or GC's.
I know that it's behind the siding but wouldn't some leaking and water damage start happening so quick as you say it would if there was a problem.
What are your reasons that it will eat up tyvek pretty quick. Are you saying that the tanins in the cedar will eat it up?
Is it a case where youn had to replace a door or window and the tyvek was eating away or maybe the door or window wasn't flashed properly?
There's been times where I've ripped out windows and doors over tarpaper and tyvek and never seen any sign of eating away on either one.
This is the site where I got the number from.
http://www.cedar-siding.org/about_us/ask-the-expert.asp
Joe Carola
Edited 9/11/2005 5:24 pm ET by FramerJoe
Joe, not to butt into this, but I recall FHB doing an article about this problem several (?) years ago. IIRC, the opinion was that the tanins in the cedar would leach out of the siding once it got wet, & get driven into the housewrap, turning it into mush. The solution was either to use a rain screen detail over the wrap, or not use wrap at all, & use felt, or rosin paper instead. Either way, it was suggested not to let cedar come into direct contact with the wrap. Maybe someone else can remember which issue the article was in.
Good thread,
Ive never heard of this.
-zen
I've seen it with my own eyes with white cedar shingles in place less than six or seven years and the tyvek getting swiss cheesy. I don't think it would matter so much (or at all) with primed stuff. I don't think water alone turns tyvek to mush, even if the job is improperly flashed. I don't think a house sided 20 years ago with tyvek and cedar would be visibly impaired, but when it's time to reside, I'll bet there is water damage where the tyvek has failed.
use 15lb felt, cedar will eat up tyvek pretty quick, rendering it useless
I don't think a house sided 20 years ago with tyvek and cedar would be visibly impaired, but when it's time to reside, I'll bet there is water damage where the tyvek has failed.
If you say that cedar will eat up tyvek pretty quick, (how quick you didn't say) rendering it useless, then don't you think that you would notice any water damage before 20 years?
If this is true, then how come it's not heard of all over and why wouldn't the Cedar Association say that their product should not go over tyvek.
Shouldn't this tyvek raise a red flag all over like this new ACQ. Isn't siding homes important enough that there should be testing done on this?
It can't just be New Jersey who has never heard of this. If this was true than every Architect and every builder all over the country should be talking about it and it should be on the plans that you can't use tyvek under cedar.
Joe Carola
I've seen it damaged after 6-7 years, I live in a cold Northern beach environment where wind-driven rain is the norm, and it's almost always foggy/wet in the morning.
Search Tyvek Cedar for more discussions.
from the tyvek website
26. Can Tyvek¯ be used under cedar siding?
Yes, Tyvek¯ can be used under cedar siding. It is recommended that the cedar siding be installed per manufacturer’s guidelines and recommendations by wood siding associations, such as the Western Red Cedar Lumber Association, including priming all surfaces including the back and ends before installing. Additionally, the use of furring strips will help promote drainage of any incidental water that may penetrate the cedar cladding.
sounds like they don't want cedar touching the tyvek to me... unless of course it's primed.
Framer Joe,
This link gives a pretty definitive answer to your question.
http://www.eere.energy.gov/consumerinfo/factsheets/bd4.html
...from the article:
"In wet climates house wrap sometimes reacts poorly with certain kinds of wood siding. Lignin (a natural occurring substance in many species of wood) is water-soluble and acts as a detergent. Like all detergents, it decreases surface tension and so destroys the house wrap's ability to repel water. Field research has shown that wood lignin makes it easier for liquid water to pass into the wall. Certain types of wood siding like redwood, cedar, and manufactured hardboard siding seem to accelerate the problem. To avoid this problem, carefully attach heavy building paper (30 pound asphalt impregnated) to the walls as a substitute for house warp or install felt-paper over the house wrap as a water repellent surface that is unaffected by wood lignin."
Drew
Joe, I edited the FHB article on this topic some years back. The info came from one of the smartest guys I know, Joe Lstiburek, who runs http://www.buildingscience.com. I saw the photos the author presented, and I buy the argument that tannins degrade housewraps. I've done tear-offs where 15 year old housewrap behind cedar was utterly shot.
Just because best practice isn't standard practice doesn't make it overkill. I've seen regions - Maryland seems to be one - where the standard practice is to install vinyl siding directly over the sheathing, with no housewrap or tarpaper. So, just 'cause it isn't done doesn't mean it shouldn't be. Andy Engel
Senior editor, Fine Woodworking magazine
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