Sloped Roof Diaphragm with Ridge Vent
Sloped Roof Diaphragm with Ridge Vent
(OP)
I am analyzing a large 3.5 to 12 roof as a plywood diaphragm. I realized that there will be a ridge vent down the center of the diaphragm that will essentially cut the roof in half (a few inches of the plywood will be removed to provide the ventilation at the ridge vent). Does this cause a major discontinuity of the diaphragm? Or is this not a concern since the stress is assumed zero at the middle (deep beam concept)? The trusses will still be intact, so will they provide the continuity?
Thanks.
Thanks.






RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
Thanks.
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
I haven't seen it (or specified) it either. That's why I asked the question - I was wondering if omitting the plywood at the ridge vent was actually a problem. Can the truss transfer the forces across the opening? I sent an email to APA asking this question. I will let you know if they reply with any useful information
RE: Sloped Roof Diaphragm with Ridge Vent
For a larger, more commercial type structure where you might have a large, uninterupted space below, I would guess that if there was a ceiling (gypsum board) attached to the bottom chords, you would again be able to use the ceiling as the diaphragm (if it worked) and ignore the discontinuous roof sheathing.
With no ceiling, though, I'd think you'd have to deal with the blocking and load path. Your thoughts?
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent
For blocked diaphragms you do need make connections for the unsupported edges. APA recommends "partial ridge venting" which involves placing blocking at alternating truss spaces. To carry the shear load, the nailing is doubled at the blocked spaces.
RE: Sloped Roof Diaphragm with Ridge Vent
RE: Sloped Roof Diaphragm with Ridge Vent