I have just finished constructing a lean to roof which covers a porch one end and acts as canopy at the other end, can anyone give me advice as to what size lead to use and how much sits as an upstand and how much is on the tiles. The top of the lean to is up against pebble dash so need to cut into this with a grinder or something any advice as to what type of blade to use in grinder and an easy way of cuttting a nice straight line any advice greatly appreciated. Cheers