I am building a shed under my deck. Got the roof installed and put it into position. Got a heavy rain last night and it leaks. I have a slope of about 6 total. Thats about all I can do The inside wall is 90 inches high and the outside is 84 inches high. This may not be enough of a slope but that is all I can really do. I figured if it was under the deck it wouldn't get hit so hard. Well I was wrong. I will be taking out the wall to see what I can do to fix this problem. I was thinking of putting plastic corragated sheets on top to give it more protection. Any ideas. Iused tar paper and roofing shingles.