I’m getting ready to install two 4’ x 10’ collectors for a solar hot water heating system. I need some advice on how to attach the collector panels to the roof.
The roof is tar & gravel, slightly sloped at approx. 12 degrees (2.5"/1’). The roof framing is TJIs spaced 2 feet OC. The collectors will be mounted parallel to the roof surface, on two rails. My plan is to put the rails on standoffs made from blocks of treated 2x4, with a lag bolt going through the rail, standoff, decking, and into the TJIs beneath.
Here’s a little section diagram that I drew up for the building department to get the permit:
I guess I should put each standoff in a pitch pocket? Is there an easier/better way to waterproof these penetrations?
The 14" space between the roof decking and the ceiling is completely filled with blown-in cellulose insulation. Any water that gets in will saturate the insulation and cause a big problem, so I really want to make sure that I get the waterproofing/sealing right.