Help needed with flat roof renovation

[Blu_Ray_UK2007]

My flat roof is deteriorating. GRP-finished goods. No redress was available since the original constructor fell through. We've had many people examine it in detail (some of whom we know, including a few builders we've employed in the past and the ones who installed the glass), and the general view is that the GRP has likely cracked even if nothing is immediately obvious. If so, it has to be replaced or at the at least, re-covered.

I'm curious about the benefits and drawbacks, especially from experts like @Darrell.

everything seems that the only option is to tear everything apart, re-board everything, then finish it with either felt or rubber (EPDM?)

Alternately, sand down what is already there and paint over it with Triflex.

Finish with lead flashing in any scenario.

[Paqngo]

One can wonder what caused the cracks. In other words, is there an issue with the framework? Or has it already been trodden upon? Or.. ?

By the way, I despise flat roofs.

[Geek2232]

If your flat roof is leaking, completely remove it and replace it. The main issue with leaks is that they seldom, if ever, occur where they first appear. Long-term costs may also be lower with a roof replacement and strip.

[BEERMAN]

Take advantage of the situation to put some PIR insulation board in place (if it hasn't been done earlier). If it's done well, either the fiberglass or the rubber system will turn out great. Don't even bother with plywood since it's worthless in this day and age, regardless of where you get it. T&G OBS3 is an excellent choice for the position.

[cumblechook22]

My friend the builder recently finished putting on one of his own flat roofs. He used that rubber (he couldn't remember the precise name), but he said it works well... if applied properly.

He offered me some extra to use in the rabbit hutch, and it seems really sturdy.

[SkippyTom]

Everyone will give you a different recommendation, but rubber or EPDM appears to have less difficulties than fiberglass, and I believe this is because of how effectively it is done in the first place. If there is any room for mobility in the construction, do you think the rubber would be more accommodating as well? 🙂

Having said that, felt, if it is installed correctly, may endure for a very long period as well - anywhere from 30 to 40 years, depending on the environment.