existing brick rowhouse + shear wall issue 3

[Ben29]

The below paragraph is mostly just a rant. My main question is: How do I attach the shear wall chords to the 18" thick stone foundation wall below the shear wall?

I have a contractor who gutted an existing brick rowhouse (circa 1900). This was done in conjunction with the "city revitalization" effort. While they were ripping the vegetation off of the rear brick wall, the rear wall collapsed. At this point, they call me up. I went down to the site and gave them a fee for providing structural documents to rebuild the wall. They said, great! but then they never paid my deposit, never signed my proposal, and never contacted me again. So I moved on.

A couple of months later they call me to come down and look at the job they did. I gave them an attitude about it, but all they did was act confused. I went down there again (I wish I didn't).

So here is the issue, they built a wood-framed wall where it used to be a brick wall. This wall is now a "shear wall" and the remainder of the house is open concept. The house is 12' wide x 45' deep. Per the code, I need to design this shear wall as if the remainder of the houses on the block fell down and this was the only house left standing. My question is, how do I resolve the uplift forces? How do I attach the shear wall chords to the existing 18" thick stone foundation wall?

 

[phamENG]

I don't envy you that one. I'd probably tell them to find somebody else if I didn't really need the work. They don't sound like the sort of clients I'd want calling me again next time.

That said, you have to anchor it somehow...so you either need to research anchorage into rubble stone (Hilti doesn't have anything, but they do link to a research paper that you could read...but why put your neck on the block for these guys?)

Some sort of column inside the wall that gets tied into your load path with a footing that can resist the uplift?

 

[kipfoot]

I think that you'll need to somehow engage the dead load of the stone, and perhaps the masonry party walls, to resist uplift. Vertical rod with an end plate in the wall? Steel anchored to foundation concrete that's under the corner?

Make sure you get the retainer, because these folks won't want to pay you when they see what the solution is.

 

[GeorgeTheCivilEngineer]

It would help to grout the rubble/stone wall
Then you'd have more confidence in the resin anchor bolts.

 

[bones206]

Hopefully nobody leans against that doorway that’s boarded up with a plastic sheet.

Is that a steel beam along the bottom of the new wall? I assume they just pocketed it into the rubble wall?

 

[Ben29]

bones: that is not a steel beam. That is a standard cmu block that was "modified" to act as a bond beam. The contractor claims that he broke out the inside walls of the cmu block as needed to install rebar "near the top of the block". So this CMU "bond beam" is worthless. I am going to tell them to provide angle lintels to support the block above the openings.

 

[phamENG]

Yeah...you really need to demand a retainer for this one. Criticizing their work and giving them a design that is sure to be "overkill"? No way they're going to pay you.

 

[Ben29]

Here is one idea.

 

[Ben29]

Pharm: Holy moley. I just figured out why you always call me "Bern"

 

[Ben29]

Pham: My idea is that I will send them a schematic concept sketch (like the one I show above). And tell them to give me a retainer so I can design it. If I never hear from them again, that is OK with me.

 

[Celt83]

Did you give them the design for what they built already, it's not entirely clear in your original post if they just built whatever or if they built a design you gave them?

If they just built what they felt like up top I'd walk away, if you accept designing a detail for the anchorage you just signed yourself up for liability for everything else they did above.

 

[Ben29]

Celt:
They just built whatever they wanted. I did not give them direction.

Don't I have some liability now since I went out and looked at it? Shouldn't I at least write a letter stating the issues?

 

[Ben29]

I will add that they did pay me for making the site visit.

 

[phamENG]

Pharm: Holy moley. I just figured out why you always call me "Bern"

Glad I wasn't drinking my coffee....I'd be buying a new keyboard...

Not loving that detail. You're going to have a moment there equal to T*7.625". Sort of like top plate rollover.

 

[Celt83]

I'd maybe have a conversation with your insurance carrier about exposure on this.

There are so many unknowns about what they did after you left the site to where it is now, a lot of risk to take on here for likely only a couple thousand in fee.

Shouldn't I at least write a letter stating the issues?

Do you know what all the issues are beyond just the anchorage, did you perform a full survey of the as built construction.

 

[SWComposites]

is the local AHJ aware of this insanity? if not then maybe a call to them is appropriate.
concur on contacting your insurance carrier, but I would also run far, far away from this fiasco.

 

[Ben29]

I called my insurance guy and he was adamantly in agreeance with Celt et al about running far away.

I did not do a complete survey of the construction. My insurance guy wants me to document everything that happened thus far. I will probably write a letter and send it to my insurance guy to review before I issue it.

At a minimum, I feel I need to say something about the CMU block that was installed. I feel like it could fall down at any moment.

 

[gte447f]

I don't see how or why you should have any exposure to liability except for your duty to public safety. You are not required to fix this in order to protect the public, since you had nothing to do with creating the situation. You should be able to fulfill your duty to the public by reporting your concerns to the authority having jurisdiction over the construction (e.g. the building department).

 

[kipfoot]

If you're not going to proceed, you might consider sending something in writing where you withdraw your proposal. Just for the record.

 

[Ben29]

I issued a 2-page letter documenting the first and second site visit, and basically all of the correspondence so far. I concluded the letter by stating that I was unable to certify the wall as it is currently built. I recommended that they hire a structural engineer to provide a design. (not me)