This may turn out to be a stupid question, but I have nothing to prove...
I don't understand why it isn't possible to make roofs cheaply, using board materials instead of tiles or glass fibre. It's possible to make boats waterproof, with appropriate sealing materials and pain, so why not roofs, which have to deal with a lot less water?
It would be convenient and cheap to put large plywood boards on a roof, make sure that there's some kind of overlap or flexible seal where their edges meet, and finish them with thoroughly waterproof paint.
I'm assuming that I'm not a genius who has thought of something that has never occurred to anyone else, and there is a reason why this isn't done
- what is it?
Daniele