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RE: Dead Load or Live Load?

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Jeff,
What do you mean by:"if the PV panels are live load they would
work, if DL they don't."? Are you planning to call it live load and reduce the load for tributary area? I hope not!

Reza Dashti, P.Eng.
Vancouver, Canada



The problem is not with the primary 42'GL beams. I can use a 16psf ll due to
trib area. The problem is that all the existing roof skylight headers were
designed right at code min. So if the PV panels are live load they would
work, if DL they don't.

Thanks all for the responses, they will help decide how to proceed.

Jeff


|~|Are the panels flat on the deck or sloped to take maximum
|~|advantage of the
|~|sun, particularly in the winter months?  If they are sloped,
|~|what maintenance
|~|is performed on the panels over the years?  What equipment is
|~|required for
|~|maintenance of any kind on the panels?  Can the roof be reroofed without
|~|removing the panels or do the panels have to be removed for
|~|reroofing?  If
|~|the panels are sloped, what is the likelihood of material being
|~|stored under
|~|the panels?  Maintenance personnel don't like to haul 5-gallon
|~|buckets of
|~|plastic cement to the roof every time to patch a leak and tend
|~|to store this
|~|material on the roof.
|~|
|~|Depending on how you can answer these questions determines how good an
|~|argument you can make to use a reduced live load for the roof.
|~|
|~|No answers, but lotsa questions!
|~|
|~|A. Roger Turk, P.E.(Structural)
|~|Tucson, Arizona
|~|
|~|Jeff Smith wrote:
|~|
|~|. > I have a 40'x50' flat roof with 10 4x6 skylights. The client
|~|wants to
|~|. > pretty much fill up all areas except the skylights with
|~|solar panels.
|~|. > Overall the panels weigh about 4psf. They are permanent, but after
|~|. > installed there is really no room left for live loads other
|~|than wind and
|~|. > rain. My understanding is that a 20 psf roof live load is for
|~|. > construction/maintenance loads. Are the panels a dead load
|~|or live load?
|~|. > Normally I would just add the panel weight to the DL and use
|~|20psf LL. The
|~|. > only reason I ask is that I am on the cusp of it figuring.
|~|
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