[RE-wrenches] Module Racking Attachment to SIP Roof

[Gary Willett]

Daryl:

Sounds like we came to the same conclusion - bolt(s) through the SIPs is the only way to go. I'll discuss this with builder - I'm not sure how the underside will be finished out but I'm sure we can work it out. Thanks for the response!

Regards,


Gary Willett, PE
Icarus Engineering / Solar Services LLC
NABCEP Certified Solar PV Installer # 031310-246
Gary at IcarusSolarServices.com

<mailto:Gary at IcarusSolarServices.com>

On 7/26/2011 8:09 AM, penobscotsolar at midmaine.com wrote:
> Hi Gary,
>    We've done several SIP projects and I've done the same research you are
> now likely doing.
>    What I ended up designing was a system of aluminum plates (8"x8") that
> screwed into the roof sheathing at four points with 1/4" ss lag screws,
> then using 1/2 threaded rod that ran through the center of the plate
> through the SIP to a similar plate mounted on the inside. We used
> bituthane between the plate and the roof, as well as silicone, then used
> standard racking with flashing. The oldest SIP job we have is now going
> on seven years with no problems at all.
>     Feel free to contact me off list if you have any questions about this.
>
> Daryl DeJoy
> NABCEP Certified PV installer
> Penobscot Solar Design
>
>
>
>
>
>> Fellow Wrenches:
>>
>> Working on a residential PV design using Structural Insulated Panels, or
>> SIP panels. Preliminary design is three AC strings of 17 microinverters,
>> in three portrait rows ~18" apart.
>>
>> The good news is that the builder wants to include the PV as part of the
>> original construction.
>>
>> The wood structural roof beams on which the SIPs will rest are on 20
>> foot centers, and run the same direction as the portrait PV modules. The
>> SIPs are 10-1/4" thick, with 5/8" plywood on top and bottom. Roof pitch
>> is 1.5:12 (low pitch).
>>
>> Are there any PV rack mounts specifically designed for a SIP structure?
>> I've done a lot of web searches, and can find no specific products.
>>
>> I've looked at the Eco-Fasten^(TM) Universal Roof Attachment Bracket. It
>> has 8 mounting holes per attachment point using #14 screws. Pull-out
>> resistance will be low per attachment point with 5/8" plywood.
>>
>> One solution could be a product that had a bolt-plate on the bottom of
>> the SIP, that penetrates the SIP with long 5/16" threaded bolt(s), and
>> then attaching to the PV mount at the top of the SIP. The UniRac
>> SolarMount steel flat-top mount has four 5/16" bolt-holes and might be a
>> good choice. This method should have no problem achieving the required
>> pull-out resistance.
>>
>> Any suggestions, installation experience, on how to put PV on a SIP roof?
>>
>> --
>>
>> Regards,
>>
>>
>> Gary Willett, PE
>> Icarus Engineering / Solar Services LLC
>> NABCEP Certified Solar PV Installer # 031310-246
>> Gary at IcarusSolarServices.com<mailto:Gary at IcarusSolarServices.com>
>>
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