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Shearwall (Braced wall panel) connection to roof wood truss

Shearwall (Braced wall panel) connection to roof wood truss

Shearwall (Braced wall panel) connection to roof wood truss

(OP)
I'm a design engineer of residential here in Texas.
A house is under construction now, and the roof structure is wood truss. Since exterior wall length is not long enough for lateral resisting system against wind load, some of interior walls are used for shear walls. Recent site visit found all shear wall panels stopped at bottom chord level for all shear walls and the contractor wanted to install plywood to cover open web of trusses at exterior walls. All interior trusses will stay as open web. Contractor uses truss clips to connect the bottom chord to top plates and insisted those clips are enough.

To my knowledge, all shear wall panels must be connected to roof/and floor diaphragms. I used to go into attics of old houses, but never find any continuous wall or panel from wall to roof diaphragm, which meant only exterior walls are used for shear walls or improper construction.

Here's a question.
Can shear wall panel stop at bottom chord of truss or continue to attach to roof diaphragm?

RE: Shearwall (Braced wall panel) connection to roof wood truss

If the truss is designed to transfer the required shear load from the roof sheathing to the top plate of the wall.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

RE: Shearwall (Braced wall panel) connection to roof wood truss

I agree with woodman here, but normally, unless the lateral load is specified for that particular truss or trusses, the trusses are not designed that way. You would have to check with the truss supplier.

If the lateral loads were not specified and the truss supplier says that the trusses cannot handle the load, then the contractor will have to install plywood on the trusses, letting the plywood span no more than 24" between the truss members. You will likely read a hard point on the roof here due to the limiting effect of vertical deflection of the sheathed truss with respect to the adjacent trusses that are not sheathed.

If the supplier's, E - MAIL OR PAPER DOCUMENTED FORM, says that the trusses can handle the loads, no worries. Otherwise, worry.

One other important point to consider: Unless the trusses were specifically designed to bear on the shear walls below, they should remain clear of the top plate of the shear wall, with connectors similar to Simpson DTC clips being used to allow for vertical deflection of the truss. If this is not done, not only are you liable to read a hard point on the surface of the roof, but you may overstress a truss member.



Mike McCann
MMC Engineering

RE: Shearwall (Braced wall panel) connection to roof wood truss

I've designed quite a few "drag trusses" that were designed to transfer loads from the roof diaphragm to shear walls. All of them were flat bottom chord trusses. All of the shear walls were parallel and directly beneath the "drag truss".

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