Techniques for Installing PV Racking on

"Rigid-Insulation-Over-Decking" roof systems.

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Flat roof before installation. This roof is comprised of gravel over paper over thin sheeting over rigid insulation over decking on rafters.

We cut holes in roofing down to the decking. These holes extend over rafters on either end.

Setting the blocks. They are attached to the roof with lags through countersunk holes.

Blocks in place. Each block stradles two rafters. The spacing was determined by a structural engineer.

After the blocks were set, the roofers applied "cant strips" to create bevels at the edges of the blocks. Roofing was tailored around the edges of the blocks to provide weather seal.

Modules in place. Racks will be lowered to about 20 degrees. All that's left is the cleanup...