I know nothing about house repairs. I had a tiled roof extension done about 30 years ago supervised by an Architect who said at the time the roof had the minimum pitch because of existing windows or something on these lines. over last few years i have had occasional leaks especially after a very windy rain downpour. for non windy rain no leaks. as the water from the roof seems to flow very slowly from the last tile to the chutes i was wondering if the space between the last two tiles could be sealed as i suspect the wind may blow the rain up between them. sorry for being long winded!