Zip Sheathing or plywood+Prosoco?
I am renovating and adding on to my home in Dublin, CA (climate zone 3C) and I’m undecided between the following sheathing WRB+AB setups:
Option 1: using a standard (un-insulated) Zip system+Zip liquid flash/Zip tape on the joints, OR
Option 2: 3/4 plywood+Prosoco R-guard series of products (J&S filler, Fast flash, Cat5)
I haven’t priced it out yet, but I would assume that they should cost about the same with Zip being more material intensive while the ply+prosoco being more labor intensive. The cost will be a determining factor but not THE determining factor; I want a system that will be durable and can have redundancy.
Also, not sure how either setup will perform on blower door test – would ideally like to get <1 ACH50
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IMO, plywood sheathing + Blueskin VP100 would outperform either of those.
Thanks Jon. Is VP100 both an Air and Water barrier?
Also, what I liked about the other systems were that I could do it myself if I needed to once the sheathing is up. Is this a system that can be done by one person? This is basically an issue as I am acting as GC for my house - it has been really hard finding people who built non-standard systems and so I am the fall back if everything else fails...
If cost is the same, my personal opinion is to prefer the plywood with liquid applied membrane. Simply for the sake of benefits of plywood as a redundancy.
But not everything is perfect and we all have to balance cost vs time vs quality vs complaining contractors
Now in all practicality, zip is osb with a liquid membrane already applied on it. So once you put your sheathing down, it's theoretically less work to then seal just the seams and flash the fenestrations.
However if you're meticulous, you would probably start sealing all the nails penetrations as well which might get you close to the same time spent rolling prosecco on plywood.
Unfortunately I've never worked with prosecco on sheathing specifically, so I'm using my judgement herd. All my liquid membrane experience is with foundation , roof membranes and flashings and they all went on without much fuss, although can be messy. But the process is the same, you roll a liquid on and maintain a continuous layer. Not rocket surgery.
As a personal preference I am not a fan of peel and stick a unfortunately. I only have a few available to me to purchase here in Toronto. Blueskin being the biggest one. If you don't roll on the primer, it doesn't stick well in most weather conditions here. You're pretty limited to dead of summer for it to hold. And even then I often see people stapling corners down because it's flapping I'm the wind. a previous window install contractor I hired, use it for the window sills, I wasn't impressed with them after a couple weeks as they came off the sheathing, and had to go augment it. Seams, wrinkles, priming, weather are all really important for a good install.
Just my 2 cents if it helps any.
Yes, it's a good air barrier and is a lapped water barrier. I don't know about DIY.
Blueskin is both the air & water barrier. It is a peel & stick. I found it on my project in San Diego to be quite ant proof also. It feels very satisfying to apply. I can be done by one person. It can be done after the pros leave.
https://henry.com/residential-and-light-commercial/weather-resistive-air-barriers/blueskinvp100
Tim,
I've never used it. How quickly does it go up?
I did watch an official installation video, but couldn't get any idea, as the two guys looked like they had never seen it before, or perhaps ever been on a construction site.
Look at Matt Reissinger videos on Youtube- he shows crews putting up a similar peal & stick. https://www.youtube.com/watch?v=Ian7lijXGk0 shows a crew installing larger sheets & a window install.
It did feel labor intensive initially, I got better at it as the job went on. It needs similar care like putting ice & water shield on a roof. big sticky sheets & getting it on smooth & to lay flat, It was easiest to stick it at a corner & align the sheet then peal the backing off as you smooth it to the wall, - I didn't prime it as it stuck to new plywood well. I also used the Grace product very similar experience.
If you're going to go the route of liquid WRB this article might lend some information which you hadn't thought of.
https://www.buildingscience.com/documents/building-science-insights/bsi-103-joints-and-corners-and-penetrations
Thank you very much everyone - this will help me a lot. I had a couple of related questions.
1. Between the 3 WRB systems (zip, peel-n-stick, fluid applied), which one would give a better level of air tightness?
2. I have a neighbor who is trying to remodel+add-on his home to a LEED Platinum standard but he is using Tyvek as his WRB - can you get the levels of airtightness needed with jut Tyvek and exterior insulation? My gut tells me, no, but he is a stickler about the details and so I am not sure anymore.
"2. I have a neighbor who is trying to remodel+add-on his home to a LEED Platinum standard but he is using Tyvek as his WRB - can you get the levels of airtightness needed with jut Tyvek and exterior insulation? My gut tells me, no, but he is a stickler about the details and so I am not sure anymore."
- Of course you can. Just have to tape the seams. Obviously taping the seams of all the layers will lead to more air tightness vs taping the seams of just one or two of them however how much more depends on the build itself and it might not be worth the effort.
For Zip, I'd go to youtube and search for "Independent testing reveals flaws in coated sheathing system".
In general, a non-fully adhered wrap provides a less effective air barrier than other things (taped sheathing seams, full adhered WRB, Zip, etc).
Are we sure that's a truly independent test? The rest of that channel is pushing tyvek hard
Those tests show the Zip, which is being used as a WRB, not a cladding, subjected to wetting it would never see. The video is a hatchet job.
While they could be lying about being independent, I see no reason to assume that. It seems quite fair that they used the same test (ASTM E331 - spray nozzles, etc) that Huber/Zip claims to use and pass.
It should go without saying that testing should exceed expected conditions (by how much is a data/testing-standards question). Without data showing otherwise, I'd assume that ASTM has a done a reasonable job in creating E331 and it *is* relevant to real use.
There are certainly legitimate questions about different results from standardized tests conducted by manufacturers in perfect conditions vs typical field installations. Would be nice to see more such tests on all the options.
Also, we don’t know who funded that test and only have their word it was constructed properly. According to Huber the issues seen here occur when nails are over driven and tape not applied correctly, and in the video the voiceover even says water infiltrated through overdriven nails. That’s poor installation. There’s plenty of examples of zip being used in the field achieving low blower door scores. Zip, tyvek, fluid applied, peel and stick-I think all can perform well installed correctly. All can perform badly if not.
Not mention that test completely lacks field validity.
Yep. Huber performed a similar test on Tyvek which showed bulk water intrusion around the fasteners (staples / cap nails...can't remember which).
They're pointless tests.
In Canada, most people using Tyvek use it only as a water barrier not an air barrier. The air barrier is done by taping the plywood, osb, foam sheating depending on what you have.
Alex, exactly.
I can't see using Tyvek as an effective air barrier. Just the number of staples involved in its installation would worry me as it blows in the wind and elongates all those penetrations. Then details around windows, roof and foundation?
Not as an air barrier, not for me anyway.
Jibu,
I've seen many houses with ZIP sheathing as the primary air barrier exceed Passive House levels of airtightness on blower door tests. I have no doubt that houses with Prosoco can do the same. The thing is, that's only one component of the air barrier and there are lots of other areas and transitions to get right to create a tight house. Here are some articles that may be helpful:
https://www.greenbuildingadvisor.com/article/one-air-barrier-or-two
https://www.greenbuildingadvisor.com/article/blower-door-directed-air-sealing-2
https://www.greenbuildingadvisor.com/article/getting-the-biggest-bang-for-your-air-sealing-buck