Ridge Skylight - Hole in Wood Diaphragm
Ridge Skylight - Hole in Wood Diaphragm
(OP)
I have a 26' long (ridge runs parallel to this dimension) x 24' wide wood diaphragm, sheathed with 1x6 wood decking. The roof is about a 6:12 pitch consisting of 2x4 trusses at 24" oc (scissor type truss). The arch/owner would like to install a ridge skylight that is about 22' long x 2' wide.
I'm thinking that this essentially creates (2) separate diaphragms (on each side of the skylight) and therefore if we provide some sort of strap and blocking on each side of the skylights than this should be acceptable. Any further thoughts on this?
Thanks!
I'm thinking that this essentially creates (2) separate diaphragms (on each side of the skylight) and therefore if we provide some sort of strap and blocking on each side of the skylights than this should be acceptable. Any further thoughts on this?
Thanks!





RE: Ridge Skylight - Hole in Wood Diaphragm
RE: Ridge Skylight - Hole in Wood Diaphragm
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EIT
www.HowToEngineer.com
RE: Ridge Skylight - Hole in Wood Diaphragm
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llr
RE: Ridge Skylight - Hole in Wood Diaphragm
Personally, as the opening is at the zero shear line of the diaphragm, plus the questionable capacity of 1X6 planks to act as a diaphragm much over 100 plf, I would consider the situation to be somewhat problematic.
Mike McCann
MMC Engineering
RE: Ridge Skylight - Hole in Wood Diaphragm
Say the ridge skylight went all the way across the roof, I still think you'd be OK just assuming (and detailing) you have (2) diaphragms, no? I mean basically you have (2) (less) deep beams instead of (1) deep beam so to find your tension/compression you would just use a reduced depth based on each 'beam'. Also your shear length at the ends would be slightly less.
If you think about analyzing a post frame (pole barn) roof where they have purlins @ say 2' on center and a metal roof - when analyzing/designing the connection of the purlins to act as chords, you can (and is done frequently) assume that each slope acts as a separate diaphragm and that each purlin is 'loaded'. I'm thinking that this would be similar where each slope acts independently.
EIT
www.HowToEngineer.com
RE: Ridge Skylight - Hole in Wood Diaphragm
RE: Ridge Skylight - Hole in Wood Diaphragm
EIT
www.HowToEngineer.com