Polycarbonate greenhouse roof techniques
 

I'm having a roughly 10' 9" x 15' green house built. The roof is going to be a shed style at about 10° angle. The roofing material is going to be 5-wall polycarbonate sheets.

I'm wondering about using glazing tape between the wood purlins (battons?) and the polycarbonate. I've seen in some places that helps to reduce the noise the panels make when the air pressure changes due to wind or opening/closing the greenhouse door. Has anybody used glazing tape?

Do we also use glazing tape for the side cladding/lites? (That is 3-wall polycarbonate?

We've got the washers with the built-in gasket and know to drill the holes 1/16 to 3/32 bigger than the screw size. And we we know to seal the edges of the the panels with breathable tape. Any other tips?

I suggest using silicone caulking under the gaskets. I've seen the gaskets deteriorate and shrink with age and sun.

The idea of cushioning the panels is a good one. Read more to see whether there are better options. I don't know.

The internal ribs must run vertically.

The top of each panel should be sealed (foil-faced tape is often used; I covered that with a plastic U-channel for added protection). The “breathable” bottom tape is to allow condensation to drain.

My PC-covered greenhouse had a metal frame. All sides of the panels were covered in U- or H-channels, and the self-drilling gasketed screws went through the central gap in the H-channel or through a metal strip over the U-channels on the perimeter, and not through the panels themselves, giving them some expansion/contraction room.

The manufacturer supplied butyl caulk for between the channels and the frame, but bathroom silicone (with mold prevention) is a better alternative, in my mind.

Thanks for all the tips. My greenhouse is almost done. I'll post some pictures when it gets done.