I have a large pergola with 10mm double walled polycarbonate installed on the roof. When the roof was initially installed the roof had no leaks, but over the course of a year the roof seems to be developing more and more leaks. The only possible area for these panels to leak is though the screw holes that were drilled to attach the polcarb to the framing. The screws that were used were some of these screws, which I purchased from Home Depot at the recommendation of a neighbor:

http://www.farmtek.com/farm/supplies...a3_FA4654.html

After talking with a specialist I found out that I used the incorrect screws for the job. I am in the process of ordering these to replace all of the current screws:

http://www.greenhousemegastore.com/p...rbonate-panels

What I wanted to find out is if anyone has used any flashing, sealant, tape, etc between the rubber gasket of the screw and the Polycarb to add extra protection against leaks. Replacing all of the screws is going to be a pain (300+ screws) and if I am going to undertake this job I want everything to be perfectly sealed.

I considered putting some silicon sealant on the rubber part of the srew in order to fill in any gaps between the hole and the screw.

I appreciate any help and all ideas are welcome.