A friend of mine is going to remove the old hardboard siding on his house and reside with fiber-cement lab siding. His home has 2×4 walls and is insulated with polyurathane spray-in insulation. I believe it is sheathed with buffalo board. My question is this: Should he put a house wrap, or does he need a house wrap under his new siding? He lives in Fargo North Dakota.
Thanks
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Replies
What's "buffalo board"? Is it that black stuff that is often called by the brand name of Cellotex?
None the less house wrap functions as both an air barrier and a secondary weather barrier. - it it keeps out water and air. Yes it is needed - either that or something else like felt paper (tar paper). Proper detailing including flashing where needed is important too. The thing you need to understand is that siding is not water proof - it's more weather screen.
Edited 4/5/2008 11:24 am ET by Matt
Southern MN here: When we resided we installed Tyvek and it made a world of difference in terms of wintertime comfort. No longer are there drafts coming from the electrical outlets. No longer is the dining room (NW corner) too cold to sit in. Can't quantify a $savings for heat, but there had to be one.
However, our insulation is conventional fiberglass batts. Blown-in foam is a much better wind barrier than fiberglass, so housewrap may not be as big a winner (but it's still in the "can't hurt" category).
If he does use housewrap he should carefully tape (with sheathing tape, not duct tape) around windows and doors, and tape all the seams. If he hires it done I'm guessing the taping job will be half-arsed at best.
Good idea to do it
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First let me say that I do not have any real experience with this. I have been hearing from many contractors in the area that Tyvek is holding in too much water. They have removed the siding in a remodel and found 12" rust circles around each nail. Granted, that this water is probably from a improperly installed vapor barrier, but how can you possibly get a vapor barrier 100% sealed?
They have all said that they are going back to tar paper with no sealing of the seams. I know that I wil get alot of hell from this post, so let er rip! I think with all of the technology out there we might just be building homes too tight.
"It is what it is."
You're not the 1st to bring this up. I have not been convinced yet of the superiority of building wrap vs paper. I've seen just as much damage on "wrapped" houses as one can come across on a papered house.
At least paper breathes. The wrap under tests breaths as well, but I don't think it does nearly as much as paper does with all the overlapping unsealed seams.
I'v now started to see some contractors leaving seams on wrpaped houses untaped on purpose.
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Edited 4/5/2008 11:26 pm by alrightythen
Thanks for the back up. Is your name a Jim Carey quote?
"It is what it is."
only if you say it like this " aLLLLLLL -RIIIIIghtyTheN!
:) View Image View Image
Both felt and tevck will allow gaseuous moisture through, ie, "breathes", but limits the flow of air, ie does not "breath".I hate the word "breathes" when it is refering to anything but an animal.The big difference is what happens with an liquid water.Both repells it.But if felt stays wet then it will allow water through and then dry back out again.So that any lquid that gets on the backside, either by minor leaks or condensation can get back out again..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Edited 4/6/2008 7:10 pm by BillHartmann
Use one or the other, whichever you're more comfortable with. Some folks like tyvek b/c you can get it in big widths.
But like Matt said, flashing details are key.
Also, I've heard of back-priming cement boards, if you're really concerned.
k
Typar performs better than Tyvek (but don't advertise as heavily).
Tar paper performs as well as or better than Typar.
Your friend needs some sort of housewrap under the siding, whichever route he goes.