I'm pretty handy around the house but have not done a flat roof before. I have a patio that has been converted into living space and I know I have one leak in the roof. I'm considering replacing or reroofing the patio myself. It's a flat (10Deg) roof with aged rolled asphalt. Can someone point me to somewhere where I can find some instructions on how to do it? Can I overlay what is alreday there? what type of material should I use? etc.?