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Re: LL on roof with solar panels.

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Good points, Daryl. When I'm on a roof, I take up at least 10 square feet of LLr...if there's only a foot between panels, do I need to lie down so that I spread my load out linearly?

Let me add - what happens if a future owner decides to remove the panels?  This is not some far-out hypothetical, like "what if the new owner decides to put on an intensive green roof." In this case , the panels are removed and no load study would even be considered since the new owner would be removing weight. 

Where I am, snow load (25-30 psf ground) always controls over roof live, and snow needs to be added to any roof fixtures, though the load path may change. You might also check for snow drifts occurring under the panels if you have a roof step or ridge anywhere and you're in snow country. That check might also cover the LLr case.

Daryl Richardson wrote:
        There are three possible load cases you should think about.  These are:
1.)    Workers who might be working on the roof plus stacked materials while they're working.  I think the code specifies a minimum of 1.0 kPa (20.7 p.s.f) to account for this.
2.)    What happens if you get a big dump of snow overnight?  As a presumption of reasonableness (not a code requirement) I would suggest about 50% of the design snow load as a minimum.
3.)    What about snow load while the owners/caretakers are on vacation?  My preference would be to design for the normal snow load.  Better safe than sorry>
H. Daryl Richardson
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