Flat Roof Solution
I finished the underside of my car port with clear 1/2"x4" cedar. I want to keep it looking nice so I chose EPDM rubber as the waterproofing material above. After nailing down T&G Sturdi-floor plywood, I rolled out the sheet of rubber. It is 60 mil. thick and was quite heavy. After positioning the rubber, I rolled 1/2 of it back and troweled down glue on the plywood. After the glue was all down, I rolled the rubber back and then did the same thing on the other half. I jumped around on it to fine tune the position and then used a roller on the rubber to remove air bubbles.
The rubber is tough enough to take a good deal of traffic, but we try not to sit on chairs or drop heavy objects on it. If one of us does punch a hole in it, a regular inner tube patch kit is all you need to make a repair. Eventually I will build a floating deck and complete the railing to match the house entry. Thats' a job to tackle in the spring. It's getting close to the end of our summer weather, and I am out of money (hopefully temporarily) to take on a project of this size.
The first EPDM roof I put down was about 20 years ago in Sacramento, CA. on my parents flat porch. I inspected it recently and the extreme heat had shrunk the black rubber so that it was tight as a drum. White rubber was not available 20 years ago, and this was a relatively new roofing material. The rubber is still in great condition, but I would use white rubber in a hot locale, to prevent shrinking and also to reflect heat away from the structure. I am going to have to go back to California and pull the rubber up and reset it, or it will probably pull away from the walls and leak.
EPDM rubber has a reported 40-50 year rated lifespan, and after 20 years the rubber still felt as pliable and elastic as when I put it down, so I don't doubt that it could last that long. It would probably last indefinitely as a membrane under a Sedum or Sod roof. Maybe I will do that on my shop - Hmmm? that gets the wheels turning. I guess that is why I am a Perpetual Remodeler, I'm always thinking of something new to start on. The roof is getting old out there.
Posted by The Cranky Codger