My shop roof is a low pitch, about 2 in 12 to 2 1/2 in 12. It currently has a rubber roof that was laid over OSB and the rubber has not stuck to the OSB well. Also, the rubber roof is ugly. The shop is attached to the back of the house. I want to install a new roof and I was thinking of laying shingles over the top of the rubber roof. Any thoughts on this?