We did one direct to S-5! installation - never again. Alignment and
leveling was a pain and the wire retaining clips on the discs were
useless. Always use rails. Aside from the installation issues, rails
will better distribute loads across the roofing seams. Without rails
you'll inevitably end up with "diving board" modules cantilevered off of
the clamps.
But really, the most important point I can make is that the S-5! clamps
are only as good as the roofing. If you look in the S-5! literature
you'll find a wide variety of tension and shear force ratings depending
on the brand, material, and thickness of the roofing. You are also
dependent upon the diligence and skill of the roofer. How many fasteners
are under there, of what kind, and into what sheathing? It's a gamble.
My response is to distribute the load with as many clamps as I can.
You'll find that the resulting factor of safety is not all that huge.
The cost, as a percentage, is not that huge either. And you'll sleep better.
Hilton
--
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602
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