Next door’s garage joins mine, they had felters(?) to do their side in and then next time it rained mine was like a sive, grr. In fairness it was probably 30 years old.
Anyway, stripped the lot, covered in marine ply then used that Wickes self-adhesive, cold applied stuff. Think it was this stuff[/url] + cap sheet. One man job over a long the weekend. That must have been 5 years ago.
Made a bit of a hash of the edging, some skill there. Rest of it was about as complicated as applying copter tape. Cost most for the ply, probably £500ish all in.