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I hired a framing crew to frame a new home in Anchorage, Alaska. When they were done I found that most of the nailing on the shear panels and seismic hardware was done incorrectly.

Many of the shear panels have nailing that is too narrow and too short. I verified with my designer and the nail manufacturer that the nails are wrong and do not have the shear strength of those specified in the plans.

Interior shear wall

Moreover, almost all of the Simpson seismic hardware on the outside of the building (twist straps and coil straps) was installed with nails that are also far too short. Simpson requires a minimum 2.5" nail when nailing through sheathing. My framers used a 1.5" nail.

Inadequate nailing on Simpson coil strap Inadequate nailing on Simpson twist strap

In other places, the nailing on the sheathing, and the sheathing install generally, is just plain terrible:

Extremely poor sheathing nailing Poor wall sheathing installation

I'm in a pretty serious seismic zone here. The 1964 earthquake was the second-largest ever recorded in history and killed over 100 people, and in 2018 we had a 7.1 just a a few miles north of the city. My home location is also exposed to a lot of wind.

How should I go about fixing the sheathing? The nailing is already extremely tight due to our seismic requirements--but the nails are all wrong. Could I pull the nails and replace them with slightly larger screws (something rated for the appropriate shear?) or do the panels need to be pulled and rebuilt?

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    I'll let our engineer-minded folk like @LeeSam weigh in on the panels done wrong, but I can tell you that pulling nails from the straps isn't as hard as it might look. Simple cats paw/hammer work. Now, putting a longer nail back into the same hole might not be great if the nail is the same diameter... – Aloysius Defenestrate Apr 20 at 22:28
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    I doubt if you could pull all the nails. They look like they were set with a pneumatic hammer (nails are slightly recessed). Removing a nail would destroy the sheathing. – Lee Sam Apr 21 at 0:05
  • How do you know the diameter (and grade: box or common) of nail is wrong? Length is not so critical and often “shorts” are provided by Simpson. I doubt you could increase the nailing to account for the wrong nailing without splitting the supports (studs). – Lee Sam Apr 21 at 0:13
  • No offense but it looks like some local teenagers did the job. Did you pay them yet? Really sorry about this. Lee Sam will probably give you the news - most of it needs to come out. Might actually save you money in labor to just get that part over with. – DMoore Apr 21 at 5:43
  • Have fun in court, assuming they actually have insurance and that insurance can eventually be made to pay, rather than simply trying to make taking them to court too expensive so you'll give up and they won't pay. – Ecnerwal Apr 21 at 17:13
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There are several issues you’ll need to resolve: 1) was a Building Permit obtained, 2) was the contractor licensed and bonded, 3) is the design correct, 4) was the installation incorrect, 5) is the installation unacceptable

1) This project requires a Building Permit. If one was not obtained, who is responsible. (The contractor will say the home owner is responsible because they are doing just a small part of the construction.) Obviously footings were poured, etc. and those should have been inspected and approved. Now, the framing should have been inspected and approved or rejected. Did the Building Inspector approve the framing? If not why not?

2) The contractor is required to be licensed and bonded. If he was not, why not?

3) Was the design correct? The designer needs to confirm that he did not make a mistake and is v CCB orrery for this installation. Designs are not random. They follow specific guidelines laid out in the Building Code for your area (region). You don’t want the design to be unreasonable, or if it is, then why the “extreme” design.

4) Perhaps the framing was incorrect. You’ll need the designer to confirm the design is correct AND the construction needs to be “fixed”. (“Fixed” May mean “replaced”.) Get their determination in writing. That way, you are not being unreasonable, just following your designers recommendations.

5) You’ll need a third party to review the installation and determine that it is unacceptable. (The contractor will obtain their expert witness and they will say it is acceptable.) Not every project is designed to the maximum performance of nailing, blocking, etc. Often, a lesser nailing pattern, smaller nails, etc. will still provide “adequate” structural performance. Your expert will need to show how the installation is defective AND make a recommendation for the “fix”.

Btw, there is a Builders Board that license contractors in your state that can referee this issue if you do not want to go to court.

Summary:

Just because it was not installed correctly, doesn’t mean it needs to be replaced. Do your homework and get everything in writing.

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  • Thanks! The structure is fully permitted and the contractor is licensed/bonded/insured. If the design seems extreme it's probably because the house must handle extreme wind/seismic stresses (mountainside in Anchorage, Alaska). The structure was specifically designed to exceed code minimums, and the framing contractor was well aware of this. Appreciate the advice re: fixes. – Alaska house Apr 22 at 21:48
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That's an unsettling discovery!

Where possible I'd make them double up the straps. Install another strap along side the existing strap with the proper nails (depends a bit on post/beam width/strap locations). Specifically what hardware was involved in your seismic design, you can do this for CS16s but SHDH10s are embedded in concrete and I've looked at the post pour hardware and that isn't fun to install so if you have those maybe pull the nails and upsize the diameter and length of the fastener.

On the shear walls you could add nails to the sheathing up to 3" oc. The on edge nailing is typically tighter than the in-field nailing so maybe you can only do it on the field nailing. The best thing might just be to double up the studs on the inside so you can get your nailing pattern. You'd loose insulation value in the wall but certain if you double the studs then you'd reach design strength.

For specific walls you could add the Simpson Steel Strong-Wall hardware which is usually designed for large openings but which can do a lot of shear in a small area. Possibly adding a few of these in select locations is better than attempting to adjust the sheathing.

Another option is putting a shear layer of plywood on the interior of the studs. That is often done in seismic retrofit when the cladding is already installed.

On the non-shear areas is much required. Did your designed spec nail size for sheathing on non-shear walls? It looks like 5/8 ply sheathing is that correct?

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  • You say “test out some nailing into 2x material with tighter nail pattern”. You know that the nailer (stud) is regulated by the nail spacing, right? Anything tighter than 4” oc requires a 3x minimum. – Lee Sam Apr 21 at 3:09
  • Interesting. How does it work if you are already at the 4" oc on the edge and you install siding that is supposed to also hit the nailer through the sheathing do you avoid all nailers on the edge of the sheathing when attaching your siding? If you put rainscreen on top of your studs for your siding how do you attach it? If you also then attach the siding through the rainscreen through the sheathing and into the nailer how do you avoid being closer than 4" oc given all the fasteners? This image shows 3" oc nailing pattern - forums.jlconline.com/forums/filedata/fetch?id=999557 – Fresh Codemonger Apr 21 at 3:24
  • This guide does say nailing at less than 3" oc can cause splitting but it also then goes on to recommend not nailing closer than 4" oc. Seems odd that they say less than 3" can cause splitting and then recommend 4". Probably just a safety factor so you don't go tighter than 3". apps.floridadisaster.org/hrg/downloads/… – Fresh Codemonger Apr 21 at 5:08
  • I still think that even where the spec is 6" oc for sheathing but you add rainscreen onto the sheathing at the nailers and then you add siding through the rainscreen, through the sheathing and into the nailer there are likely a lot of 4" oc fastener violations. I take your point though, I'd avoid spacing tighter than 3" oc. Maybe go with a deformed shank nail for extra pull out resistance in the places where you can add a fastener. – Fresh Codemonger Apr 21 at 5:12
  • The Simpson STHD14 is used with maximum 1/2” shear panel (plywood). See page 3 near bottom: fastenersplus.com/SSP%20Applications/Clickstop/fp_webstore/img/… It looks like the OP used 5 ply 5/8” plywood, which could exceed loads allowable. The Code does not address “additional” nailing of siding, etc. (to my knowledge). – Lee Sam Apr 21 at 5:38

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