Is using Zip System Sheathing on a ventilated roof a waste of money?
brentwilson| Posted inGeneral Questionson
On a ventilated cathedral roof where the ventilation channels are below the sheathing, would it be a waste of money to use Zip System sheathing? Why or why not?
Climate Zone: 6B
Snow Load: 80 to 100 pounds live load
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Replies
My thinking is that the air sealing properties of Zip sheathing would be pointless if air is being intentionally vented under the sheathing. Is that correct?
Brent,
I agree, and the advantage of not having to use a WRB that you get with Zip on walls is also not there with roofs.
Hi Brent.
Though I have heard nothing but good stuff about the quality of ZIP tape, if it were my build and if I wasn't looking for the air sealing qualities of this product, I would use a wood panel sheathing and a high-quality, mechanically-lapped roofing underlayment.
Waste money if you still have to/choose to apply an underlayment because the manufacturer of the asphalt shingles or whatever you choose to use won't warrant their product when used on ZIP.
Remember the whole purpose behind ZIP is that it's an All-In-One product designed to replace sheathing + wrb.
“All in one”.....because its so tough to wrap walls.
It’s a heavily marketed product in trade shows, free license CEU’s, salesmen push it, rebates, free rollers, reps throwing out gift cards (I know because I got all of it) and they were smart and made it green, a little homage to the Hardees orange. Green Building Advisor is crawling with it.
Use it if it works I guess, but number wise in dollars and sense it’s not worth it, can get the same or better for less.
The market will decide on whether or not there are sufficient cost savings by going ZIP vs OSB+housewrap. In my area over the last couple of years it seems to be the go'to product for custom builders. Tract builders are using their own branded housewrap w/OSB or another product which I call "cardboard sheathing".
Hooray for capitalism! YMMV.
You proved my point and the market has decided. Tract building is about numbers. If ZIP shaved dollars off cost, smart tract builders would require it. But they don’t use it, because it doesn’t help the bottom line.
Custom building on contract, the more I can convince someone to spend, ie explain all the wonderful benefits of this amazing product referred to, as an example Zip sheathing, the more money I make since my margin is on total cost not to mention kickback rebates to give me some extra lunch money.
Don't get me wrong, if someone wants it, I’ll use it and take the money. But as a builder being honest, my opinion of it is it isn’t remotely necessary.
YMMV
We don't have large-scale tract home builders where I live, but the production-minded builders are all using the Zip system as far as I can tell. It's rare to see a new home go up that's not "green." (For the record, their thicker panels are reddish brown.)
I never could see the appeal of Zip roof sheathing. The only one I see is the speed of getting water tight.
If you must have the cathedral ceiling I say put most of the insulation on the outside with a vented roof on top. Like peanut butter must have jelly cathedral must have pot lights. And there is just never enough room in the joist space for good insulation, air barrier, pot light and ventilation.
Walta
如果你不打算把完成材料your roof right away go with zip. The exposure time is far superior to OSB. If you are going to put your roof on in less than a month stick to OSB and underlayment.
The underlayments I use with a plywood roof-deck are all rated for six months exposure.