I all, I'm pretty new to the DIY game, so this may be a silly question.
I've just about finished putting up and 8m x 4 M Pergola (the kind that's right up to the house roof). I've got mostly tin on with 2 sheets of plastic. Now I've still got flashing to do, but I've been told to put some rubber type filler under the plastic before I lock it down, also under the flashing. The problem I have is I understood I can drill (with the roof screws) straight through the tin/plastic and into the rubber, but the screws just wind up the rubber.
Can someone explain why I need the rubber and a technique for getting it in place. Eg. glue it in place with IronNail then screw in?
If you could post a picture, it would help with my understanding of the flashing detail.
The rubber seals out the water from going down the screw shaft. It only has to be a little snug, You might try some soap on the washer to give it more slip and less grab.