GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Audio Play Icon Headphones Icon Plus Icon Minus Icon Check Icon Print Icon Picture icon Single Arrow Icon Double Arrow Icon Hamburger Icon TV Icon Close Icon Sorted Hamburger/Search Icon
Q&A Spotlight

The Framers Botched Their Job on ZIP Sheathing

Overdriven sheathing fasteners compromise structural integrity as well as the water- and air-barriers

Not a job for the ages: Sheathing nails in many areas have been driven too far, in some cases disappearing into the foam backing of this OSB sheathing. Sealing tape is poorly installed. What now? [Photo credit: 88 Clayton]

The Zip System R-sheathing that 88Clayton has chosen for his house is structural OSB sheathing with a water- and air-resistive coating applied to one side and a continuous layer of insulation applied to the other. When installed with Zip Tape, the sheathing provides the WRB for the walls and becomes an integral part of the house’s air barrier and thermal envelope.

But when most of the nails attaching the sheathing to the house have been overdriven, some disappearing into the layer of foam insulation bonded to the back of the sheathing, Clayton wonders just how effective any of this is going to be.

“The framers building my house severely over-drove 90% of my sheathing nails on the Zip-R,” Clayton says in a Q&A post. “It’s into the foam in many cases. Thousands of nails. Not to mention, their tape job is horrendous, with improper lapping.”

What to do next? Clayton isn’t sure whether it’s feasible to tape over every single one of the nail holes. Should he cover the ZIP sheathing with a layer of housewrap? Or, is there some other way of fixing this mess?

That’s where we start this Q&A Spotlight.

Consider a liquid-applied flashing

Spenceday suggests that Clayton consider using Liquid Flash, a liquid-applied alternative to ZIP Tape made by Huber, the same company that manufactures Zip sheathing.

“It may sound daunting,” he says, “but Liquid Flash may be an option here. It would be faster than taping to dab each hole with Liquid Flash and a putty knife. Same for fixing problematic tape joints or fish mouthing.”

Like Malcolm Taylor and other GBA readers, Spenceday raises another issue: if the nails are that badly overdriven, has the shear strength of the sheathing been compromised? What are the structural consequences of this sloppy work?

Clayton may have to renail some of the sheathing to make sure it’s attached properly and provides the structural strength it’s designed to add to the frame of the house.

GBA Editor Martin Holladay points to a technical document from Huber that may help. In it, the company makes two key points:

  • Install extra fasteners (or reduce allowable shear capacities) if any fastener is more than 1/8-in. overdriven or if more than 20% of the fasteners are overdriven by between 1/16 in. and 1/8 in.
  • Overdriven fasteners don’t automatically void the Zip System sheathing warranty, but fasteners that miss framing completely should be removed and the holes should be covered with Zip tape. Fasteners that go roughly halfway through the OSB, or more also should be covered with tape or liquid flash.

Huber pays a visit

Clayton has been in touch with the manufacturer, and the company has sent a rep to the house for an inspection.

“One of the area reps, Brian, has been great,” Clayton writes. “He met me out on the job site and we did a thorough walk-around as I pointed issues out to him. He also noticed some things I had not seen and offered ideas on solutions.”

One thing they agree on is that the nail spacing is, in Clayton’s words, “pretty atrocious.” Fasteners are sometimes no more than an inch or two apart in clusters of five or six overdriven nails.

“He agreed with me on the severity and thought it would be an airtightness issue as well as exposing the raw OSB to moisture,” Clayton continues. “He recommends using longer strips of tape to cover rows of holes, rather than little pieces. He also suggested Zip Liquid Flash as an alternative to tape but said it would take longer.”

Among the problems they’ve identified in addition to overdriven nails are:

  • Panels with edges out of alignment on outside corners.
  • Poorly taped sill pans at windows with beveled cedar siding installed so that the sill will hold rather than shed water.
  • Gaps in sealing tape along with curling edges, indicating the tape was not rolled out.

“This has to be one of the worst framing crews ever,” Clayton says. “I have a custom builder of some notoriety in my area. He’s built dozens of homes in a very respectable neighborhood full of custom upscale homes. I expected much better than this. They don’t really supervise the crews. Just unleash them for days at a time.”

Another Huber rep who Clayton spoke with on the phone suggested that housewrap might be a good solution.

Do we expect framers to do too much?

In broadening the discussion, Taylor suggests that builders may be expecting too much from framing crews, that some of the details of successfully completing a building enclosure are beyond their interests or skills.

“I wonder if there isn’t a mismatch right now in what we are expecting framing crews to do?” Taylor asks. “It always seemed problematic to me that we left installing the windows and doors to framers. It makes sense from a sequencing perspective, but it’s not a great skill match. Now we are asking them to tape sheathing and apply membranes to rough openings.”

Framers like to frame buildings, he adds, but he’s never met one who expressed much interest in water-resistive barriers, flashing, or air-sealing.

“That’s not an excuse for doing shoddy work,” he says, “but I don’t see any good from loading more unrelated tasks onto framers that don’t have much in common with their primary skills.”

Point taken, replies Zephyr7, but framers certainly should be able to hang sheathing and know enough not to overdrive nails. And in this case, the builder may need to educate his project manager.

“His project manager, who has failed to sufficiently supervise the framing crew, had ‘never heard of rolling the tape’ and ‘never heard of a J-roller,'” Clayton says. “Apparently he’s never looked at Zip tape before, which has ‘ROLL THE TAPE’ printed all over it.”

Next up in the building schedule, after the sheathing has been repaired, is window installation. Clayton has already lined up a meeting with the builder to ask for different window installers.

Our expert responds

GBA’s technical director, Peter Yost, had this to say:

First, nail guns can be dangerous. Not too long after I started at the NAHB Research Center (now the Home Innovation Research Labs), Hurricane Andrew struck south Florida. That was in 1992. Houses in south Florida built by Habitat for Humanity hit the national news because they consistently kept their roofs on during the storm when most others did not. Engineers from the Research Center conducted HUD-sponsored damage assessments in south Florida and I ended up working on construction waste management for Homestead Habitat. I saw the damage first-hand.

One of the main reasons that Habitat-built houses kept their roofs is that volunteers nailed on roof and wall sheathing by hand, with nary an overdriven fastener or “shiner” (a fastener that missed the framing).

This is not just a problem with ZIP sheathing. Every type of structural sheathing develops its full rated shear resistance only when fasteners are driven flush, in accordance with the manufacturer’s instructions, standardized testing, and the building code:

“IBC 2304.9.2 Sheathing fasteners: Sheathing nails or other approved sheathing connectors shall be driven so that their head or crown is flush with the surface of the sheathing.”

How much does overdriving affect shear capacity? Below is a chart from the Structural Building Component Association (SBCA) that addresses that question.

Nail guns notoriously lead to overdriven fasteners, and to shiners. Here are three rather simple adjustments you can make to reduce overdriven fasteners significantly.

  1. Depth adjustment: Most nail guns today have this adjustment built in to the nail gun.
  2. Inline pressure regulator: About $30.
  3. Aftermarket flush nailer collar: About $10 (see the photo below).

A nail collar can help prevent overdriven fasteners. [Photo credit: Peter Yost]
This is not a product problem. It’s an awareness problem. This is all a long way of saying that overdriven fasteners are certainly not unique to Zip or Zip-R sheathing. What is unique is that overdriving Zip or Zip-R fasteners compromises both structural and water management, and shiners compromise structure, water management, and airtightness.

Is it a good thing to combine functions into one system of related components the way ZIP can be a water-resistive barrier and part of the home’s air and thermal barriers? You bet it is, but it comes at the price of workmanship potentially trashing all three elements of performance.

The problem is not with the components or the system. The problem is with job site awareness of building science and high performance. And that is exactly why here in little old Brattleboro, Vermont, our local Sustainable Energy Outreach Network is developing a high-performance building certification within the National Center for Education and Research (NCCER) Core Curriculum for Level 1 Carpentry. Our local builders have been demanding that everyone who gets hired have an awareness of what high-performance building means. That means that if your exterior sheathing is structural, your water-resistive barrier, and an air barrier, you get triple points for flush fasteners!

25 Comments

  1. User avater
    Armando Cobo | | #1

    In general, most Builders today are “Cell Phone Builders”; many have Superintendents, and have no need to be on jobsites or get out of their air conditioned Ford 350. The lack of education is the norm in the industry. Many states (including TX) do not require a license, nor minimum education requirements. When I teach classes, my first question is - how many of you own a code book? - Usually is 1 out of 30-40 builders. Most classes I teach are attended by the same 30-40 builders, out of hundreds of available Builders in most metro areas, and it’s worse in rural areas. Every week I hear “I’ve been doing it this way for thirty years and you ain’t teaching me squat”… my usual answer is, you been doing it wrong for thirty years!
    Most Builders or Homeowners hire draftsmen that charge a dollar per square foot for plans without full details or specifications, and it’s up to the trades to figure out how to build the house and know the codes, which almost always, they don’t.
    Cities do not provide sufficient budgets to educate Building officials to the latest codes and even less for building science. Code enforcement is delegated to third party inspectors, and many of them pass their inspections to keep the account; as two HERS raters and verifiers here in Dallas told me awhile back “If I flunk my inspections, I may lose my job or account, and at the end of the day, we have to feed our families”. Many rural areas do not even have code enforcement.
    Few Homeowners will study and research for good Designers or Architects and Builders who have good education and experience with good building practices, and they believe since the Builder is the “Professional”, he most know everything. The reality is a sad state of our industry!

  2. User avater
    Dana Dorsett | | #2

    It's Monday morning- is it time to pet the peeves yet? :-)

    This article sports multiple instances of "sheer" in place of the intended "shear". While homonyms, they are not synonyms.

  3. Malcolm Taylor | | #3

    I have no experience with Zip-R. Is there something about it that makes it inherently more difficult to nail properly?

    1. Jon A | | #4

      No. It takes someone spending one extra second to think about what they are doing and maybe an inline air regulator so the guy nailing the sheathing can dial his pressure down from the guy facing nailing LVL's.

      This is a huge problem with framers. My town's building department started doing sheathing inspections about a year ago specifically because all of the issues listed in this article and how common they were. We've seen framers have to rip off sheathing panels that were so over nailed they were useless for shear strength. I wont even get into negative effects on air tightness causing numerous failed blower door tests and costly retrofits.

      Lucky that the homeowner caught this one. Most houses are unchecked by building inspectors, homeowners, general contractors before the siding contractor shows up and hides in all.

      1. Malcolm Taylor | | #8

        Monkeying around on site this morning with my homemade panel (a scrap of plywood and foam), it's a bit trickier than putting sheathing directly over framing because of the different densities the nail travels though. Still nothing you can't adjust for, but I can see why this problem would occur a lot more frequently with Zip-R than regular sheathing.

    2. User avater
      Armando Cobo | | #5

      IMHO, not as long as you follow manufacturer's instructions to the "T", which is seldom done; storing sheathing clean or cleaning sheathing before taping. following nailing patterns, proper taping and rolling tape.
      I rather specify taped regular plwd/osb + taped outsulation with staggered seams + a 3D WRB for the same price of ZipR, giving me a better chance to possible overcome same installation failures and have no/less moisture problems, plus I believe that the rigid foam needs to be on the outside.

      1. Malcolm Taylor | | #7

        Armando,

        Temperamentally I feel much the same way. Keep the structure as a discrete thing. Don't compromise it for energy efficiency by substituting materials, or using techniques like Advanced Framing. Then add the layers you need to meet your performance goals.

  4. User avater
    Reid Baldwin | | #6

    On my house, the framing crew was the one subcontractor that was willing to learn something new and do things right. We had a meeting ahead of time between me, the general contractor, and the lead framer to go over the detail drawings. That gave him a chance to ask questions and express concerns. They taped the sheathing seams, installed the rigid foam, detailed the WRB, installed the windows, and installed the siding as drawn. They complained that the taping was tedious, but did it.

    The insulation and HVAC contractors weren't so cooperative. I didn't ask the plumbers or electricians to do anything very out of the ordinary.

  5. Scott Wilson | | #9

    This is the second article I've read on this site (the first was about window installers doing an incredibly poor job of installing windows) where the crew has ruined the entire job, either through ignorance or carelessness.

    If the homeowner is posting questions on this site (and therefor must be reading articles on this site) then they must care about house construction. So why not be on site when the crews are going to be doing the work? Watch them install the first ZIP sheathing panel (or the window) and if they do it wrong have them change it. Why wait until the entire job is done and then cry "Oh, NO!"?

    If you know more than the crew, and want it done a particular way (or just according to the manufacturers specs) then you should be on site to make sure that it's done correctly.

    1. User avater
      Reid Baldwin | | #11

      Frequently, the ability to pay to have a house build goes with having a job of your own.

  6. Trevor Chadwick | | #10

    Why not make them strip it off, and do it again correctly?

    1. Hugh Weisman | | #12

      agreed.....that might be an expensive lesson for the builder, but how else are they going to learn if they don't read and comply with manufacturer's instructions.

  7. User avater GBA Editor
    Brian Pontolilo | | #13

    As the homes, the materials we use to build them, and the systems we put into them get more and more complicated (or just different from what we are used to), and as builders, architects and other professionals tackle their first high-performance projects, there's a need for education. And it's not just the designer or builder who needs to understand both the why and how of the process. That info has to trickle down to everyone involved.

    I've visited a lot of high-performance homes during my time at FHB and one of the things that always amazed me was how well-versed the homeowners were in the design, materials, process, and science of their projects. That seems like a sign that someone, likely the architect or builder, did their job really well. Another commonality among many of these projects were meetings with the architect, builder, and all of the subs before construction started and/or at crucial times during construction. Everyone has to buy into the project, or they can respectfully back out.

    In fact we published an article on this idea a while back, which may be helpful:
    https://www.greenbuildingadvisor.com/article/a-better-approach-to-design-build

  8. David Hollman | | #14

    Overdriven fasteners may be related to nail gun use, but I'd bet the severity of the overdrive is increased due to the foam backing.

    With wood-to-wood contact between typical sheathing & framing, the framing will absorb some of the compression of the sheathing wood fibers and halt the nail at a certain depth. But the foam backing probably does not do this and therefore allows the overdrive to go much farther in, potentially weakening the connection a lot more.

    1. Malcolm Taylor | | #18

      David,

      The difficulty is also increased by the margin by which the compressor is set to cycle. If it is too large the gun might be driven by air between say 85 and 110psi. The structural engineer I use hates owner-builds because they typically use small portable compressors, and tasks like nailing off sheathing produce waves of over and under driven nails.

      1. David Hollman | | #19

        Malcom, I believe it. When I've done my own work I usually set the gun to leave the nail a little proud and then true them up by hand. Takes more time though...

  9. Stephen Crane | | #15

    In the Seattle area, shear nailing inspections are so routine for every jurisdiction that only the newbies screw it up. My framer is paranoid about failing inspections so he has the crew set the margin of error of the guns to slightly underdrive the nails rather than risk overdriving, and then the next day I hear him banging on the exterior with a hammer to finish any proud nail heads.
    These guys have been working for me for 10 years and I know all their idiosyncrasies. Another builder called them morons. I replied, "They may be morons, but they're MY morons." I can predict everything they do. I know exactly when to intervene. If they refuse to attach rigid roam I just wait 2 weeks till they're short of cash and they're happy to bring extra ladders and helpers and git 'er done!
    The secret is to thoroughly understand the weakness of your subs. A first time builder doesn't have this luxury. I know each guy of my technical trade subs. If there's a new employee I watch his work like a hawk because I know he's still learning, even if the company itself is 25 years old.
    Without independent supervision the sky is the limit for mistakes. Some mistakes are so grotesque it's tempting to every metal object in your tool belt at the clown.
    Just remember that if there are 3 possible interpretations of a given operation, there's only a 33% chance your workers will perform it the way you think it should be done.

    1. Andrew C | | #16

      @ Stephen - "...if there are three possible interpretations, there's only a 33% chance they'd do it the way you think it should be..."

      You, sir, are an optimist. Personally, my experience says the chances are less than 10%...

      1. Stephen Crane | | #17

        LOL!! Very true, Andrew. The optimist says 33% the realist says 10% and the pessimist says 3%

    2. Marc Bombois | | #23

      "The secret is to thoroughly understand the weakness of your subs."

      Haha! Could have been written by Machiavelli.

  10. Charles CAMPBELL | | #20

    Seems to me the foam between the framing and OSB will lower the shear value regardless of whether the nails are properly driven.

    1. Malcolm Taylor | | #21

      It does, but Huber provides nailing schedules to compensate depending on the required shear loading.

      1. Charles CAMPBELL | | #22

        I'm curious to know how close Huber advises spacing. A professor of civil engineering once told me he gets nervous when nail spacing is closer than 4" OC.

        1. Malcolm Taylor | | #24

          Charles,

          A link to the nailing schedule: https://www.huberwood.com/assets/pdfs/ZIP-R-Sheathing-Installation-Guide.pdf

          We are in a high seismic zone here on Vancouver Island, and our engineers routinely call for nailing 2", 3" and 4" oc for shear walls.

          1. Charles CAMPBELL | | #25

            I've seen callouts for that kind of spacing, but at what point do you split the stud? The professor must have had a reason for concern. In the field of the panel and at the plates you can stagger the nails, but usually not at the vertical edges.

Log in or create an account to post a comment.

Related

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |