Hi-
I am a bit of a novice in construction, and building my first new home. The general contractor likes the Tyvek wrap, but I have been seeing Zip System in a lot of other places and I like the concept of the sheathing, waterproofing, and some insulating aspects all rolled into one package. There is a lot of Tyvek-based information on the internet saying Zip System is bad, while a lot of Huber-based information saying Tyvek is bad. I am looking for some independent and hands on feedback. Thanks!
Replies
The 2015 International Residential Code R703.1.1 requires a "water-resistant barrier". This isn't just code, it's desirable since most house sheathing products are untreated wood products subject to rot and decay over time if in regularly contact with bulk water (rain), incidental moisture or condensation (droplets).
The house wrap products are often woven spun products originally developed as air infiltration barriers to maintain fill insulation values degraded by wind blowing through it. But these typically allow water to pass through them and are not water resistant. Just air.
This is what the Huber Zip and competing products accomplish, as well as the spray on moisture barriers that have been available for longer in commercial construction. They also have a second important feature: they are vapor permeable. They allow moisture vapor to pass through them while still resisting liquid moisture. This is quite different than products like polyethylene sheet which are essentially vapor impermeable and that trap vapor against them in wide swing climates typical across most of the US. These products were popular in the 1990's and are responsible for a lot of the in-wall mold experience many of us have seen.
The wrap manufactures have developed more advanced products to compete. But the key is that whatever you use is required to, and ideally should, resist "water" by a demonstrable test standard, not just "weather." It is interesting that recent research (by FHB and sister site GBA) have pointed out the usefulness of simple asphalt felt to accomplish the same result, which is still permitted by R703.2 from days of old.
I plan to dig into this exact topic in the coming month, but my sense at this point is that the testing/finger pointing between Tyvek and Zip is a lot like political commercials - it's all being skewed to suit their arguments. The short answer is that both products work well if installed according to the instructions. That's the key, and that's where each can fall short. For example, if Tyvek isn't tucked tight into corners, siding contractors might slice it in order to fit their cornerboards, that's a problem. If overlaps are reversed, that's a problem. If the wrap is left exposed too many months, that's a problem. There are problems with Zip if installed incorrectly, too. Usually this comes down to the tape not being applied correctly. The sheathing has to be free of dust, and the tape has to be rolled out to ensure adhesion.
-Justin
Fine Homebuilding
Justin,
Very interested to see what you come up with. I've only recently learned about the Zip system, and like the sound of it's performance for air-sealing the house. The part I don't get is the reliance on adhesives for water-proofing.
Whether it was felt or tyvek, good lapping of materials on vertical surfaces was critical for shedding the moisture that inevitably gets beyond the siding. It seems that Zip system seals horizontal joints with the tape. I'm sure that works great initially, but I'm skeptical of the long term performance. Adhered products all eventually peel back a little bit at the edges. As soon as that happens on a horizontal joint, you have a spot that traps water. I suspect that area will get worse as water sits in it, and eventually lead to failure in that area. With Tyvek, the tape is applied to help with the air-tightness, right? But failure of that tape at an area would only minimally affect the air-tightness of the house, without affecting (properly lapped) Tyvek's water-proofness.
What does Zip have to say about that? Maybe they've tested the product in a way that shows this isn't an issue? I just haven't seen any discussion of it, and it seems like a weakness.
We use a little Tyvek and a lot of Zip System. I see no reason for Tyvek to exist now that ZipWall is available.
Well, there is always the issue of OSB not having the hold on nails (siding or roofing) that is found with plywood.
Zip wall edges can swell especially on cut pieces if they get wet. What would be great is if they applied the zip wall coating to regular 5/8 inch plywood.
That's true so we wrap all exposed edges with Ziptape or paint them with Red Guard. No swelling and no problems. The joint edges that are taped aren't exposed to water.
As a custom home builder constructing Passive House level air tight homes, there is no comparison. I can get a a house to 0.60 ACH50 using the Zip System and strategically applied accoustical sealant. We have done several houses using this method. All confirmed with blower door testing. No way that is happening with Tyvek. That is Zip Systems biggest advantage. Tighter homes mean less drafts and better comfort. We still use Tyvek on garages, but after three years of using Zip I'm not going back to the old way.
this old reprobate still uses plain old 15# tarpaper felt.
4 mil poly sheet under the inside wallboard.
Here in PNW with almost zero need for air conditioning that works best.
Other spots witht he hot moist air outside conditions are different.
Who's to say what the longevity of a tape will be. There is an article here on FineHomebuilding written by Martin Holladay titled "Backyard Tape Test" where they did some crude testing on various tapes. He even posted a follow up 10 months later and reported that the Zip tape was still holding strong to OSB. Keep in mind that this was just ordinary OSB, not even the Zip Sheathing for which it is formulated. Peter Yost also wrote a blog for BuildingGreen where he tested various tapes and reported that the Zip tape was the only one that didn't fail. As far as my own personal experience I have inspected an area of wall under vinyl siding that was three years old and the tape was still holding strong and showed no signs of degradation.
What the cost difference in using Tyvex vs Zip on a house? Total cost including labor. Also does Zip-R save you money vs. using Rigid insulation and OSB?
The Zipwall material itself is only a couple of dollars a piece more than regular OSB. The tape is where the money goes at $.37 a foot. I've seen installers use full strips to cover nails, ( we use polyurethane sealant on nails) which would give you a per sheet tape cost of about $11.00. We tape as we go so we don't have to come back and because the wall is finished when we are. On large apartment complexes, I've seen them wait a week or more for a taping sub to come tape everything at once. I don't like that as it leaves the joints open long enough for moisture to get in.
The Zip System isn't cheap. It probably costs about $0.75/sf in materials vs $0.45/sf for regular osb and tyvek. But you do save on labor not having to put the Tyvek on. Every project is different, but by the time you factor everything in, I bet on a 2000 sf ranch house it probably is only $450 more for the Zip system. I like to think in terms of cost payback though. If a tighter house saves on my heating and cooling bills, then $450 dollars more is money well spent.
Thanks, I'm wondering of the new LP WeatherLogic will put more price pressure on Zip, since they are very similar products.
LP has to pay, Huber licensing fees to use their technology so they have an expense that Huber doesn't.
Do you know this for a fact? From my discussions with LP it sounded like they were not licensing the technology, simply competing with it. Huber also filed suits against LP for this reason.
Assuming we can depend on the article in JLC that I read a few weeks back. The article concerned the lawsuit and that LP would be paying Huber a licensing fee.
I just used zip on my first job and don't recommend it.If your framer does everything right it is good but expensive (especially tape), but if your framer overdrives nails as mine did you are supposed to fill every hole or wrap the house anyway, but in any case the zip warranty has been voided.
I will go back to CDX with GreenGuard Raindrop for my upcoming project as I'm not an OSB fan ... great product as long as water never gets to it, but if it does you could go bankrupt fixing problems as many builders in my area have ... for $2-4/sheet more I'll go with CDX, and especially on the roof as it is more rigid.
Just an aside - If your framer overdrives all of your sheathing nails you may have more to worry about than the zip warranty. The shear capacity of braced walls is severely compromised with overdriven nails (if greater than 1/16" into sheathing). This has become a much bigger issue lately and inspectors are starting to flag this. You should make sure they dial in their guns or use a collar to make sure they do not overdrive. Make them hand-nail braced walls a time or two and they will likely figure it out quick enough..
What sort of collar are you referring to? Never seen such a thing.
I think it is called a flush mount attachment. APA recommends its use with shear wall nailing and I have seen it referenced in some ZIP publications as well
I wasn't aware of that but definitely makes sense, thanks.
I just built a house with Zip after using a lot of Tyvek over the years. Here's what I've found:
Zip does cost more than commodity OSB and Tyvek in the end, but the Zip OSB is much better quality than the cheap OSB and Zip gives a MUCH better air seal. If it's your own house, then that should be important to you.
Don't let your cut edges of Zip get repeatedly soaked. They will swell, but now that you know that you will just cover or tape them before it rains.
I just don't think it's possible to get the kind of air seal you get with Zip by using Tyvek. Even when I'm on site and supervising or doing the Tyvek myself, I don't think I've ever seen a perfect install. But even if you did get a perfect install, it's only a weather barrier since you're not sealing the bottom of the Tyvek.
At best Tyvek is an umbrella while Zip is a spacesuit.
The truth? If you’re doing a custom build your nuts not use zip- Tyvek is not a bad product especially when you use the more robust commercial grade and especially the version that has a virtual rain shedding barrier/space throu wrinkles on the product. And their latest liquid flashes and flex tapes are excellent. However in the field most guys hate to do house wraps so you always see it flapping in the wind and just stapled (get out of here) and unless project manager is on top of them like white on Rice forget it. The virtue of zip is its easy to supervise- you can tell if the tape was rolled properly and applied in right place simply by looking at it at end of the day. (“That trope is not straight over the seam , or I dotn see the zip Z on that strip-you didnt roll it !”) Spec builders dont use it because it’s somewhat more expensive. But they will spend money on closed cell in walls, and more pensive windows , but not seal the house with zip ? Huber currently says the warranty is not void as long as you can still see the nail head . I know everyone likes to use their old Hitachi nail gun but for Petes sake an aftermarket collar to prevent overdrive nails is only $10. Tyvek is a bit more vapor permeable than zip I will concede., but if you are thinking of having any exterior foam , zip R is a no brainer despite the price. I know of no easier cheaper consistent , in the field, easily verified way get a tight hosue than with zip - (and thats before you use zip liquid flash to get a Zip “2.0” install = insane air tightness (ie you must figure out a way to get. Some replacement air in a zip 2.0 house to balance pressures.) and NB with such tightness you can easily go with very cheap fiber gall batts in studs to get a Great wall system. ZIp has only been a round for what 13 years, but I’m unaware of any reports of properly applied and rolled zip tape peeling off so far. And their tapes have been recently upgraded and their adhesion is ever better than original zip tapes. I readily concede CDX with a stick and peel or stick applied product is ideal, but that is considerably more expensiev than zip. Your biggest problem is most production and spect builders framing subs wont be familiar with zip and the GC wnats to save $500 for hsi own pocket-stand your ground. Otherwise you will ahve to be own site for days making sure they install Tyvek properly and they don’t penetrate or cut it as another poster has noted. Zip isn’t perfect after all as. Another poster noted its still OSB (not to be confused with their advantech, but its. Good quality OSB t least. TYvek is so cheap you can even make a case to apply that OVER the zip (or even better a entry level Benjamin Obydyke rain gap product) , esp the rippled version of tyvek that shed water amazingly well . If you do use Tyvek insist on button nailing! NB Both Dupont and huber have GREAT local reps that will come out and Teach your crew proper install methods, esp important For windows. regardless of which product you decide on you decide, avail yourself of this resource. FYI USG now has a competing gypsum based product to complete with zip, but i dont see any big price advantage and the tape, while easier to cut, is thinner (yuck) . NB tyvek now has a very promising liquid spray on product that shoudl get some traction int he future. As for roofing, I dotn like the prospect of any OSB product, BUT, the thicker brown “roof” zip, WITH some felt paper on top to prevent bonding and help ensure against leaks and copper valleys , ice-water shield bottom three feet, valleys and around all penetrations certainly cant be critiqued by anyone. once zip figures out how to get a rain gap on their product they will kill their competiton.
So, after that sales pitch, do you have any direct comparisons of buildings with interior poly plus exterior:
1. no wrap
2. old fashioned 15# tar paper
3. tyvek type only
4. zip only
5 zip plus tyvek
data [;lease -one earlier post did show some blower door comparisons.
HMM, no paragraphs or sentence breaks, meant to be seamless like zip
My next house will still use 15# tar paper.
Last house with tar paper outer shield had 50 Pa door test at NL=0.02. 100% Interior poly, 13 ply Baltic birch sheathing and floor, poly between 2 floor layers, all elec outlets/lights sealed with foam, 8" stud walls 24OC with FG insulation. Bath vents sealed for test.
Great for PNW climate, interior poly probably not so good in Gulf states though, eh? .
The only comparison I've got is our house in Southern MN, built in 1976, originally with drywall, FG insulation with poly barrier facing, "beaver board" sheathing, tarpaper, and cheap hardboard siding. Replaced the siding with excellent quality Masonite Woodsman (alas, no longer available) after 10 years, and when we did, we removed thre tarpaper and installed regular brand-name Tyvek, obsessively taped.
After this the house was noticeably warmer, and outlets where previously one could feel the wind blowing through from five feet away no longer produced any perceptible draft.
Does anyone know whether zip is available in canada (Ontario, specifically). And more importantly, what do building inspection officials think of it? I’ve only ever seen OSB and tyvek used, and assume this is because our regulators haven’t caught up with the times. Any insight from members?