Shear Wall Questions

[Reborn]

I am trying to add a new, single gang box for an outlet 3 feet above an existing one on an interior wall. My plan was to run NM-B from the new box to the existing one below it and pigtail into the existing, lower outlet. I made my cutout for the old work box and found plywood below the drywall. Did some internet searching and have concluded that this wall is a shear wall. There is surprisingly little information out there about what's allowed with shear walls, so I turn to the experts here in GJ.

This is an interior wall separating the family room and a bedroom/bathroom. The location I want to cut is against the bedroom and pretty much in the middle of the wall (horizontally). This is a load bearing wall on the first floor. It seems to also be a shear wall, and I'm in California (earthquakes). At most we are talking about a 1-gang cutout for a box in the plywood, and maybe one other, smaller cutout near the existing receptacle (if the plywood goes that far down) if I need access to fish the NM-B into the existing box.

Can I go ahead and make the cut(s) into the plywood?

 

[Jim greengo]

I wouldn't worry about it,but I'm in nebraska.

 

[larry4406]

Some of our homes have interior plywood shear walls.

We run electric in them and have various devices per the electric plans - single gang outlets, 2-gang light switches, etc. I can't imagine you adding an additional outlet will be fatal to the wall's mission.

 

[Reborn]

Some of our homes have interior plywood shear walls.

We run electric in them and have various devices per the electric plans - single gang outlets, 2-gang light switches, etc. I can't imagine you adding an additional outlet will be fatal to the wall's mission.

I totally agree, haha. Hearing a few viewpoints along these lines would help build my confidence in this opinion, for sure, but I'm more concerned about insurance/code related aspects if something were to happen.

 

[alfredeneuman]

A "Simpson Shear Wall" is listed as a unit and cannot be modified in any way.
Thankfully their use is limited (pretty much) to exterior walls.
(I cut into one to install an outlet and the carpenters went ballistic ).

 

[manwithtools]

You will be fine if just adding a single outlet. I wouldn't give it a second thought. I lived in CA for a few years and have seen many shear walls with switches and outlets in them.

 

[sparky 1971]

Just do it. It's not like it's a microlam beam. I don't know that I've ever seen a shear wall, but I wouldn't give a second thought to cutting out a 2"X4" piece of plywood.

 

[loganb]

In an interior application like this an outlet shouldn't matter, cut it in cleanly so it looks like it belongs and move on.

 

[sparky 1971]

A "Simpson Shear Wall" is listed as a unit and cannot be modified in any way.
Thankfully their use is limited (pretty much) to exterior walls.
(I cut into one to install an outlet and the carpenters went ballistic ).

WTF did they expect you to do? Put it in the floor?

 

[PCustoms]

It's not like it's a microlam beam.

Brings up a question to the OP, are you sure it's a plywood shear wall and not a gluelam beam?

 

[sparky 1971]

Brings up a question to the OP, are you sure it's a plywood shear wall and not a gluelam beam?

probably not a glue lam beam since he cut the hole in the wall and can see the plywood, it's probably the edge of a 3/4 or 1/2 plywood that is visible. And a beam in the wall between the two openings would make it awfully difficult to fish from high to low.

 

[PCustoms]

probably not a glue lam beam since he cut the hole in the wall and can see the plywood, it's probably the edge of a 3/4 or 1/2 plywood that is visible.

Maybe the OP should ad pics, as reading again he says "below". I took it to be he cut the drywall, and under/behind that was plywood.

If it is a plywood shear wall, sounds like the outlet below is already cut in to it?

And a beam in the wall between the two openings would make it awfully difficult to fish from high to low.

Absolutely.

 

[acer66]

WTF did they expect you to do? Put it in the floor?

The ones I have seem were smaller like a 3x8’ prefabbed piece and just a part of the whole regular wall.

 

[sparky 1971]

The ones I have seem were smaller like a 3x8’ prefabbed piece and just a part of the whole regular wall.

3' high and 8' wide? I've never knowingly seen one. He didn't say what room it was, but if it isn't the kitchen, bath, or garage, nobody is going to want an outlet higher than 3' unless it's for something specific such as a wall mounted TV.

 

[acer66]

3' high and 8' wide? I've never knowingly seen one. He didn't say what room it was, but if it isn't the kitchen, bath, or garage, nobody is going to want an outlet higher than 3' unless it's for something specific such as a wall mounted TV.

Sorry, 3’ wide and 8’ high.
Basically just a shear wall section to support a whole wall but I also have seen a few units in a wall all depending what loads need to be dealt with.

 

[manwithtools]

Shear walls in seismic zones are pretty common and they are not like Simson Shear walls on either side of a garage door opening. They are often walls that span the entire width of the building. They can be the typical 2x4 on 16" center framed walls with 5 ply 1/2" plywood nailed at some crazy nailing schedule - like 2" on the perimeter and 6" in the field.

 

[sparky 1971]

Sorry, 3’ wide and 8’ high.
Basically just a shear wall section to support a whole wall but I also have seen a few units in a wall all depending what loads need to be dealt with.

I was confused but I think I get it now. The plywood is behind the drywall. I thought under meant at a lower level, as in the top of the plywood is at 3' and the bottom of the hole is a couple of inches above that.

Either way, right or wrong, the hole is cut. Might as well put a box and wire in it.

 

[alfredeneuman]

WTF did they expect you to do? Put it in the floor?

They framed a floor to ceiling "popout" section for it that spanned the stud bay. It looked like ****, but the outlet was required.
Slab floor.

 

[Reborn]

I can see the point of confusion. Here's a pic. With the amount of drywall removed (single gang box size), I feel pretty confident that it's plywood and not some sort of beam. Second pic was to show the outlet ~3feet down but I didn't want to move all the baby proof **** to get a good pic, so sorry about that. It at least shows why I want to do this little project The other visible holes/removed paint is from a prior tv mount that I removed.

The discussion (and thanks for it!) here got me thinking. According to my stud detector, there may be a horizontal beam (2x4) just below where I intend to place the new box, roughly where the lower tv mount bar is located. I was going to drill a hole in the 2x4, if it exists, to get the NM-B through, but that is even more significant than removing a small amount of plywood. Comments on this would be appreciated too.


I am leaning toward just doing all of this, as I can't imagine any of it would be devastating to the structural integrity of my house, but I want to understand the theoretical/insurance ramifications.

The other thing I will be doing in ~2 weeks (time is not on my side) is pulling out the existing outlet to see if I can surmise what's going on around the box - does the plywood extend all the way down? Hopefully will be able to learn something there.

 

[PCustoms]

1. That's OSB
2. I would really check the lower outlet to see how it was done
3. Drill a small (1/8") hole to see if that is indeed sheathing

 

[manwithtools]

It's possible that a forward thinking builder put that sheathing there in anticipation of hanging a TV on that wall. I' have seen that done before.

Sounds like a good excuse to get one of these: Endoscope Camera with Light Only $33.00

Drill a small hole in the OSB and feed it down the wall to see what's up.

 

[Reborn]

I've got one. I'll report back after I check the existing outlet and/or drill a small hole and scope behind.

 

[larry4406]

We have shear wall details that fully sheath the interior side of an exterior wall with 1/2” OSB. Outside and inside have prescribed nailing pattern.

Electric boxes nailed to stud with expected 1” net (1/2” OSB and 1/2” drywall).

OSB wall to wall and sill plate to top plate. Then overlaid with drywall.

 

[Toolfool]

An electrical box cutout is not a problem. After cutting the upper opening, fish your wire UP through the lower box. It will be easy to find it inside the stud bay with a coat hanger.

 

[Innovate1]

The discussion (and thanks for it!) here got me thinking. According to my stud detector, there may be a horizontal beam (2x4) just below where I intend to place the new box, roughly where the lower tv mount bar is located. I was going to drill a hole in the 2x4, if it exists, to get the NM-B through, but that is even more significant than removing a small amount of plywood. Comments on this would be appreciated too.

Drilling a small hole for NM-B through the 2 x 4 isn't going to significantly affect the strength if it's through the 4" (actually 3.5" for those nit-picky folks...) face. If there are horizontal 2 x 4s in the wall I'm guessing it is just small pieces between studs and maybe fire blocking. If it's fire blocking I think you are supposed to put some sort of fire caulking around the wires. It also might have been required at the joints of the OSB to help tie the panels together - I have seen that required in shear walls.

 

[Reborn]

I hate to bump this up, but a lot of you gave me thoughtful responses and I'd like to show that I appreciate it, and also provide closure. I finally got around to taking this on again, and here is where things have landed.

1.) I pulled back the existing, lower outlet. From my inspection, there is OSB there as well, and best I can tell, it's the whole wall.
a.) Re-reading the comments, I should add that this wall spans approx. 1/3 the width of my house.
b.) There is a shower on the other side of this wall (not where I'm working, further down). Perhaps that's a reason for the OSB?

2.) Based on the comments here and my own intuition, I went ahead and cut the OSB where I want the outlet. Looking around, I found the following:
a.) I have a clear path and cavity to the lower outlet, making the rest of this job easy.
b.) There is OSB as far as I can see.
c.) The OSB is only on 'this' side of the wall. The opposite side is drywall only.

3.) In trying to open up another tab on the existing, lower box, a chunk of the box broke. So I will be pulling the existing box and replacing with an old work box. I may have had to end up doing that anyway to avoid cutting an additional hole (and removing OSB) to fish the wire into the existing box. The job is straightforward from here, so I won't provide a final update about the job.

Thanks everyone!