Guys, cleaned the roof and it's managing the rain much better!!! There's a few bits where the nail/screws have been drilled to the joists where water is leaking through! What can be done re these? I've seen you can buy screws with washers but not sure I want to get on top of the asbestos roof and start playing about with the screws!!? Other alternative would be to silicon from the inside maybe - bodge job thou!?