Do I need ice and water shield with a zip system roof?
drewfridley7
| Posted in General Questions on
8×24 structure. Shed style roof with 2/12 pitch. Zip system roofing flashed with a mix of zip tape and zip liquid flash.
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Your local Building Code dictates this based on your location and building use. Ie Are you in a cold climate and is the building heated in the winter?
What CZ are you in?
In my area (Kansas City metro), we have to use it.
I’m in Richmond, VA. Zone 7b. We have all the seasons. It will be heated in the winter.
Isn't almost the entire state of VA in Zone 4?
I am not sure what zone you're talking about. I go by hardiness zones for gardening. I am in zone 7b.
drewfridley,
https://www.greenbuildingadvisor.com/article/climate-zone-map-including-canada
In the IRC, R905.1.2 states the case: https://codes.iccsafe.org/content/IRC2021P1/chapter-9-roof-assemblies#IRC2021P1_Pt03_Ch09_SecR905.1.2. Like spenceday wrote, whether you're required to use I+WS depends on where you are and what you're building.
The real question is. Why select Zip roof system?
I fail to see any advantage that is remotely worth it higher cost!
If you have already bought Zip roof the smart move is to stay away from whoever sold you on the system.
Walta
I always spec the Zip system for roofs, except for rare occasions. It is nice and flat so it goes down quickly, and by taping the seams it is water-tight enough to progress with interior work while you wait for the exterior trim and roofing to be installed. Prices and availability went a little crazy during the pandemic but I believe that has mostly settled down now. Have you worked with Zip sheathing?
Yeah, I like Zip because it's quick to dry in. You don't have to worry about it blowing off like roofing felt or getting torn when you walk on it.
I don't know how it stands up over time or how it reroofs. I wouldn't be surprised if when it's time for a reroof it needs replacing.
I used it on my whole house--additions on two sides and a down-to-the-rafters reroof on the rest. On a renovation like this, it is more than worth it for the reasons stated by others. You get dried in very quickly and minimize risk to the structure, extra important in a renovation with existing finishes to preserve.
Obviously each job is different, but I certainly appreciated it.
I used Zip for the roof because I used Zip r for the wall sheathing. It’s a tiny house build, so it was only six sheets. Thanks for your concern.
It's funny - everyone focuses on one aspect of the question (do I need to use an ice and water shield on a ZIP roof) and never asks what's going on top of it. The ice and water, if installed, is just one layer in a system.
You also have to consider the finished roof material. Asphalt shingles, an exposed fastener metal roof, a standing seam metal roof, a rubber membrane roof?
With such a low slope you might not get a warranty from the manufacturer of your finish roof material (or the installer) if you don't use an ice and water membrane. You should ask the finish roofing manufacturer if you need one with their product.
I’m installing a standing seam metal roof. I bought the metal already from someone who had enough left over from a job for me to use (because my structure is only 8x24).
Good point, rockies63. Drew, under a metal roof you need to use high-temp ice and water shield (at the eaves and transitions, in a cold climate). The regular stuff can melt and run down the fascia, I learned the hard way long ago. Grace has two categories of product that are more heat-resistant than their regular product; one is butyl instead of bituminous or maybe they both are, I don't recall.
Grab a piece of rubberized asphalt peel and stick, and compare with Zip tape. They're a totally different class of product. I love Zip tape, but the self-healing abilities and ruggedness of a high quality peel and stick like Carlisle are something I'd never give up on a 2:12 roof. Plus 8x24 just isn't that big, and even if you are not very building-savvy, you can definitely put on peel and stick with a friend on a not-windy day.
Thanks. Great points. I’ve only seen Grace’s shield sold near me. Is this the same kind of product you’re suggesting I can use?
I am leaning completely the other way. CDX plywood with ice shield over the roof. Don't see big advantage with huber.