kc, I had my roof done last summer. I have three portions of the roof that's flat and I elected to do those parts with a rubber roof. What the contractor did was after tearing up the old roof, they put down a special kind material similar to 30lb roofing felt. Then on top of that they put the rubber. It came in rolls like rolled roofing does and then they melt it down onto the roof with a blow torch. I have been told that with this, my flat roofs should last 25 years. As far as cost. A 20'x40' area was $900(that includes the tear down.