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multi-wythe brick (1800s construction)

multi-wythe brick (1800s construction)

multi-wythe brick (1800s construction)

Please see two pics attached.

The inner wythe of brick is bowed inward between first and second stories of a three-story building. The wall is a sidewall and is independent of neighboring structure (city block). I only have the two pics to go off of.

My initial thought is that the inner wythe is not interlocked with the rest of the brick. This is a load-bearing wall, and over time the compressive strength of the inner wythe was exceeded by the floor and roof loading above it.

I am not sure if this is lime putty mortar or not (late 1800s construction), but should not matter unless the brick was exposed to water from a long-term roof leak.

I am looking for opinions on what caused the wall to bow inward. I don't have a lot to go off of here.


RE: multi-wythe brick (1800s construction)

Take a prism of the remaining bricks and test them in compression. This will help you determine if the roof and floor loading might have caused it. Likely the floor joists were set in pockets in the brick. Check to see if they were locked into the pockets and from long term shrinkage of the joists, finally pulled them to adequate eccentricity to cause failure.

Why is the exterior wythe independent of the interior wythe? Doesn't even look like there was mortar between them. Is the exterior wythe supporting any internal loads?

RE: multi-wythe brick (1800s construction)

From the pattern of the brick layout in the portion of the wall remaining, you should be able to determine whether or not the wythes were tied together with header courses. From the first photo, it is hard to tell, but it does not look tied together. I have seen similar walls with bulges where many of the header bricks were cracked, thus reducing the connectivity between the wythes. I have seen the bulging result from a) long term water intrusion, or b) wood framing for a porch roof attached to the brick pulling away the outer wythe (porch footings were settling). If there are other areas of the building where the wythes are not tied together, but have not yet failed, possibly could be pinned together using Helifix ties.

RE: multi-wythe brick (1800s construction)

I agree with the other commentors that the inner wythe was never connected to the other wythes. If you look at the first photo there is no evidence of sheared headers. In fact, since the wall is so dark, possibly from soot and pollution, could the inner wythe have been built at a later time, maybe to provide more strength to the wall? The wall never acted compositely and failed as you stated.

As for the mortar type, portland cement wasn't made in the US until 1871 and didn't really get used a lot until the early 1900s. You can tell by scratching some of the mortar from the inner wythes to see if it has any hardness. For a mass wall like this, you don't rely on flexural resistance from the mortar very much so lime:sand mortar could have been appropriate.

And this could all be academic since the wall may have to be replaced anyhow...

RE: multi-wythe brick (1800s construction)

Masonrygeek has said pretty much all you need to know. All we've got is your 2 pictures and our previous experience to go by here, but it looks like your building was erected after the one to the right, and for whatever reason they deemed one wythe of brick sufficient to carry the new structure. It might have been sufficient (well, obviously it was for quite a few decades) but it didn't get the little bit of help it should have in the way of lateral support and it looks like a moot point now. It's too late to do retrofit ties, which are quick enough and easy enough in the right situation; tear it down and frame a new wall to replace it.

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