Does anyone no what size Herzim strip I need
To fill in about 6ins gap were the strip as shrunk
I've tried to measure the thickness I've come up with 12mm I want to cover the gap because their is a awning rail screw visible and I don't want water to get in through the screw cheers Phil.

Can't answer your question but want to comment that the "Herzim" strip is just decorative and does not keep the water out. Your scews should be individually sealed already.