Potential Project sketchy?

[shacked]

I recently met with a contractor to look at a potentially new project but I am a little hesitant as to whether I should take this on.
Here is the situation:
An existing 3 story above grade, wood framed condominium, built sometime in the 60's that is supported on a concrete slab and concrete beams above a parking garage. The unit is located at the ground floor, so there are 2 other units about this one. There is a 17ft long interior double sided wood framed shear/bearing wall in the unit that the owner wants to add a 3ft wide opening. Supposedly all of the units are laid out the same, therefore this wall supports 2 other floors above and a roof. See attached picture.

The only issue is that there are no existing plans available. The wall sits directly on top of an existing 18" square concrete beam, reinforcement unknown. Also, since I do not have existing plans I do not know the actual layout of the other units and since they are individually owned it would be hard to verify each one above.

With all of the unknowns I am very hesitant about taking this project on. Just curious as to some of your thoughts about this or how you would approach this.

Thanks

Erik

 

[DaveAtkins]

My response has nothing to do with structural engineering, and everything to do with liability.

Most companies I have worked for over the years avoid condominium work. The main problem is there is not just one owner, but multiple owners who can sue you if something goes wrong.

DaveAtkins

 

[ProLuke]

Hello,
What I would do is make sure the building is at least as strong after the project as before - so if you're making a 3' opening in the wall, I would see what plywood was removed and what was the nailing pattern. Then I would calculate the shear capacity of that removed plywood and add that shear capacity to the wall line with the new hole - either by adding plywood where there was none before, adding more nails to the plywood if that helps, or adding Simpson Strong Walls.

Calculate a header for the new opening.

For the concrete beam below, my though is it should be just fine. A 3' opening is not very big. To verify with calculations, I would calculate the moment in the beam before the hole and after the hole to see if adding the hole adds moment or shear to the concrete beam.

--Luke

 

[msquared48]

I would second what Dave says...

Aside from that though, is this wall a party wall or a partition wall? Is it a bearing as well as a shear wall?

If it is non bearing, and I mean TRULY non bearing as in a vertical gap between the top plate and the bottom of the floor joist above, then I would not be as worried.

I would still shy away from the project as Dave said though.

Mike McCann, PE, SE (WA)