too late in year to replace roof?

I would like to re roof my garage and to do it with rubber roof. i would like some instructions on how to do this since i never did it before

I have a mysterious leak that happens when it rains. It is in a carpeted area right by a sliding glass door. I thought rain water was going under the threshold and had the door replaced. The contractor used alot of caulk under and around the new door's threshold. that was last april. it rained pretty good last week and the same spot on the carpet is wet again. it doesn't seem like the moisture starts right at the door's edge but rather in about a foot and spreading towards the door. The area outside the door is a concrete patio, with some hairline cracks leading to the doors threshold. The subfloor under the carpet is concrete slab covered by a old brown linoleum (the house was built in '63). Does anyone have any ideas as to what might be going on? i thought I should call the door contractor to have them check their installation, but I watched them install the door and I think they did a good job.