What is the best type of flat roof? I'm trying to establish from the TPO rubber membrane and the IB PVC objects
Answers: PVC is slowly being phased out of as frequent materials as possible because of its environmental and health related impact. I would travel with the rubber. Try to buy white as powerfully, it will improve your cooling bills and cause the surrounding space more pleasant.
If at all possible build your roof up to dispense it at least somewhat pitch. A flat roof, no matter what stuff you use, will allow water to puddle up surrounded by spots and will eventually leak. I'm a retired building contractor and I would not BS you on this. Building the roof up will cost a short time extra but it will lower your insurance premiums and your roof is less expected to leak. If you don't build it up you might as resourcefully go next to the cheapest material available, pitch and gravel roof, but you're asking for additional repairs further down the road. HONESTLY.