24" oc rafters

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bobdog
bobdog Solar Expert Posts: 192 ✭✭
in PV Installers Forum - NEC, Wiring, Installation #1
Has anyone installed a solar system (grid tie or off grid) on a roof with 24" OC rafters? If so, was there anything special that needed to be done? Thanks.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: 24" oc rafters

    It's all about structure.
    Mine has 24" OC (Off Center in this case :p ) rafters. But it also has 2" thick "sheathing".

    Those rafters could be 2x4 trusses or 2x10 "snow load" beams. They could be sheathed with 3/8" OSB (yes, it's allowed here. I've no idea why) or 3/4" plywood. The distance between the rafters isn't the only factor, you see.

    If you can access the underside (always a good idea if only for inspecting to see what's there) you can add structure as needed to be sure the panels can be supported.
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  • bobdog
    bobdog Solar Expert Posts: 192 ✭✭
    #3
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    Re: 24" oc rafters

    Unfortunately the only access would be to cut a hole in the roof or ceiling as there is no attic per se. It is a manufactured home with vaulted ceilings. However, I do believe they are 2x6 truss style rafters with a 20lb snow load. We get little if any snow here in southern NM. My guess too is it is covered with 3/8" to 1/2" sheathing of some kind.

    Tim
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: 24" oc rafters

    Can you walk on it? if so, is there much deflection?

    Difficult to evaluate structure if you can't get a look at it. Manufacturer's specs might include full info. At that point you'd probably need a structural engineer to determine if it's feasible.
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