Got a bit of a leak in the roof of one my sheds. The roof is constructed of box-profile sheets and there are some small leaks around some of the fixing screws.
The real problem is that the slope on the roof is probably too shallow for these type of sheets, but I can't do much about that at the moment. A few weeks back I replaced many of the screws - with the correct type, new washers, etc - but that hasn't solved the problem. I'm thinking of covering the offending screws with some kind of trowel-on mastic but I'm not sure which is the best type to use. Any recommendations?