[RE-wrenches] The perfect solar ready roof

[Andrew Truitt]

If you ask me this is a dream scenario.  The scary thing about S-5!s is that
you rarely know how often the roofing panels are attached to the decking and
how well the decking is attached to the framing.  In this case you can
direct the roofer to fasten the roof as often as you want.  I had a PE do an
analysis for a sure-fire acceptable attachment method for a standing seam
roof given: 90 mph wind zone, 18" wide standing seam roofing panels,
flush-mounted PV array (modules to rail to S-5!s, no tilt legs), and his
result was that if the roofing panels are fastened every 4" along each seam
you are in the clear.  He did not address the decking-to-framing attachment,
but while the roof is off you could add as many fasteners as you want.  If
the structure of the roof is in question I would definitely have a PE look
at it and stamp the plans before proceeding, but once you have everything
under the roof robust and approved, you are primed and ready for a
worry-free, penetration-free S-5!-to-standing-seam array install.

In another email string someone mentioned issues with S-5!s slipping down
the roof due to snow which is why I recommend attaching at every seam and
breaking out that torque-wrench when installing.

Good luck!


Andrew Truitt
NABCEP Certified PV Installer™ (ID# 032407-66)
Truitt Renewable Energy Consulting
(202) 486-7507
http://www.linkedin.com/pub/andrew-truitt/8/622/713



"Don't get me wrong: I love nuclear energy! It's just that I prefer fusion
to fission. And it just so happens that there's an enormous fusion reactor
safely banked a few million miles from us. It delivers more than we could
ever use in just about 8 minutes. And it's wireless!"

~William McDonough



On Wed, Oct 20, 2010 at 2:32 PM, Kristopher Schmid <solman at legacysolar.com>
wrote:

What about screwing in double 2x6s flush to the roof deck between the beams
where your feet will attach and lag bolting into that?  Definitely check
with the beam manufacturer first, though.



Kris

Legacy Solar
864 Clam Falls Trail
Frederic, WI 54837
715-653-4295
solman at legacysolar.com
www.legacysolar.com

-----Original Message-----
*From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Scott McCalmont
*Sent:* Wednesday, October 20, 2010 12:00 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] The perfect solar ready roof

In general, you shouldn't drill or cut the flanges on engineered wood beams.
I think that eliminates lag screws into the rafters. They probably wouldn't
have the same pull-out strength as a lag screw into a conventional rafter,
either.

Scott

On Oct 19, 2010, at 7:58 PM, Chris Daum wrote:


  Dear Wrenches:
 I have a composite (shingle) roof at hand, and the owner wants to upgrade
it to a metal roof and install a 5kw+ array on it.   The rafters are those
(sort of) particle board I-beams covered with 1/2" plywood (and shingles).
What's the best metal roofing you could suggest--and would you beef up the
wood to lag into?
 Thanks for all your input.
  Chris Daum
Oasis Montana Inc.
406-777-4309
406-777-0830 fax
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