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Could anyone be able to tell me if this is a shear wall just by looking at this picture? This is a 1940s home, renovated in 2000s near San Andres fault, Northern California.

This wall is now replaced with glass and door was relocated to the other side. Should I be worry if this is in fact a shear wall? Thanks.

enter image description here

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  • At first glance, this wall does not seem structural. It would bear its own weight, but not much more. There might be structural posts on either side - these would need not to have been touched. On the other hand, in the 15 years gone by you would have noticed crack formation if a structural part had been unwisely removed.
    – ALAN WARD
    Commented Jul 28, 2015 at 10:42
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    On the other hand, there is that angled brace running between two studs to stiffen the wall laterally.
    – Craig Tullis
    Commented Jul 28, 2015 at 20:35
  • @Craig Yes, I was wondering about that bit myself.
    – ALAN WARD
    Commented Jul 28, 2015 at 23:28

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I'm no expert, but AFAIK, the frame of a shear wall is (by definition) clad with plywood, OSB, or somesuch, not just with sheetrock. From the looks of the chunks of sheetrock on the floor and remaining on the frame (top center), only sheetrock appears to have been removed on “this” side (exposing the framing we can see). The other side, which we can only see the back of, looks to be sheetrock as well, based on the white seam you can see just above the noggins, which looks like the front white finish paper folded over the edge onto the brown backing paper.

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  • Not true! The Code allows for diagonal bracing without plywood, OSB, etc. in fact, diagonal bracing was very common “way back then”, because OSB had not been invented yet, and plywood had just been introduced, but was not commonly used.
    – Lee Sam
    Commented Aug 9, 2019 at 22:49
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I'm in the process of seismic reinforcing my house (built in the 1910s) and from what I've seen, yes that wall was originally intended to be a shearwall. It has a doubleheader and the diagonal bracing was -- for the time -- their attempt at giving it some shear strength. It might have originally clad in plywood or plaster and lathe -- now long gone.

You might want to have a structural or seismic engineer come take a look at your house -- even if that wall isn't structural, there might be other enhancements you might want to make before the Big One comes.

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In residential wood construction today, shear walls are almost always constructed of plywood panels specially nailed to the framing. They are common on exterior walls since there is often plywood sheathing anyways, although they can be interior. The diagonal piece shown in the photo may be a remnant of construction

Unlike vertical load-bearing walls, shear walls do not necessarily have to be continuous from the top of the structure to the foundation, although they typically are. So if there is no wall or foundation underneath this one that is a good sign.

However I should point out that building codes, especially seismic codes, have changed dramatically since your house was built. It may be impossible to tell if there was any seismic design done at all, unless the house has been substantially renovated. From some quick searching online it looks like seismic codes in California were not systematically applied until the 1960s. In the absence of dedicated shear walls, regular framing, drywall, etc. does provide a small amount of lateral resistance. I doubt that little wall was doing very much but technically you probably did weaken the structure a bit.

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  • You have it backwards: bearing walls do NOT need to extend full height (due to headers, etc.), but shear walls need to extend full height so they can fasten into the roof diaphragm, or second floor diaphragm, etc. Yes, almost all wood frame shear walls are made out of plywood or OSB board TODAY. But this house was built in 1940’s, when diagonal bracing was common. Oh, and yes the Code gives a shear wall value for gypsum board (1/2” and 5/8”), but not plaster. (See ICC Chapter 3.)
    – Lee Sam
    Commented Aug 9, 2019 at 23:00

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