Mechanical Chases next to wood shear walls in podium wood buildings

[TDobber]

I am working on a 5 on 2 podium building. I see often the advice to avoid using as shear walls walls that have mechanical chases next to them. Can someone elaborate why that it? Is the concern having openings through the top/bottom plates?

 

[driftLimiter]

Openings through the top and bottom plates could cause an issue where the top plates are your drag or chord elements.

Chases near hold downs could cause an edge distance issue with Hold down anchorage.

Mechanical chases could lead to penetrations through your shear ply through the life of the structure maybe more?

Would like to see a specific case of what your talking about to be able to elaborate more.

 

[milkshakelake]

If it's small chases next to the wall, I don't really see a problem. If it's a large opening next to the wall, it acts similar to a façade shear wall and I still don't see a problem if everything is detailed correctly (part of the diaphragm isn't getting transferred to the shear wall and would need additional chords and connections and stuff, though a joist can act as a chord in this case). If it's through the top/bottom plates, I see a big problem.

 

[TDobber]

Thank you. Based on this, it seems like these are not usually a problem as a floor opening as long as the diaphragm forces are detailed for and the chases do not require any penetrations through the plates.

What about shear walls that are next to bathrooms similar to the attached - would the sink and toilet end up requiring plumbing penetrations thought the top/bottom plates of the green shear wall? Do walls get furred out in such situations?

 

[1.392DL]

Large vertical mechanical chases are typically "rated" and two layers of gyp are applied on the inside and outside of the walls which can make it real hard to be combined with a shear wall; something to discuss with the architect. Toilet drains are typically 3" diameter with hole bores of 3-1/2", which can take away a lot of meat from the top cord of your SW.

 

[TDobber]

Thanks 1.392DL. Why would it be any harder to incorporate a rated chase wall into a shear wall vs any bearing wall. I am failing to see the issue - what am I missing?

 

[1.392DL]

The gyp would split the plates and the sheathing, so maybe its possible to fasten studs together on each side of the gyp, but probably not worth it in general when you also consider the intricacy of getting the wall finishes flat and attaching the top cords for compression thru the gyp.