Flat roof refurb advice needed

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Londonscottish

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I have a flat roof that's leaving. Finished in GRP. Fell out with the original builder so no recourse there. Have had a number of people look at it at length (some of whom we know inc a couple of builders we've used before and the folks who installed the glazing) and the consensus is that the GRP has probably cracked even though there's nothing visible to the naked eye. If that's the case, it needs to be replaced or, at least re-covered.

Interested in the pros and cons esp from those that know - eg @Darrell ?

The choice seems to be rip it all up, re-board it and finish it either with felt or rubber (EPDM?)

Or sand down what's there and paint over with Triflex.

In both case, finish with lead flashing.

Thoughts?
 
One thought is why has it cracked? IOW, is there a problem with the support structure? Or has someone walked on it? Or.. ?

BTW, I hate flat roofs with a passion.
 
If you have a leak on a flat roof, strip it all off and reroof. The big problem with leaks is that they are sometimes not, if ever, in the place where they appear. A strip and reroof maybe also be cheaper in the long run.
 
One of my mates is a builder and he has just done one of his own flat roofs at his home . He used that rubber (not sure the exact name) he swears by it ...if done correctly.

He gave me a spare bit of it for the rabbit hutch , it looks like tough stuff.
 
Everyone will recommend something different, but rubber/EPDM seems to have fewer problems than fibreglass which I suspect is down to how well it is applied in the first place. If you have any possible movement in the structure perhaps the rubber maybe more forgiving too? :)

Having said that, properly applied felt lasts ages too - 30/40 years I have seen sometimes depending on where it is.
 
Our extension was covered in rubber, Firestone to be exact. Apparently if it fitted correctly, it's guaranteed not to leak for 20 years. The guys that did it also said if it does ever leak you can easily fit a patch to seal it again very easily.
 
One thought is why has it cracked? IOW, is there a problem with the support structure? Or has someone walked on it? Or.. ?

BTW, I hate flat roofs with a passion.
The theory is hairline cracks in the glassfibre cause by contractions/expansions. The most recent put some flashbanding over the area he thought was leaking. I'll soon find out if that theory holds any water. Boom tsh.
 
Good news; the flashband has fixed it for now.

Thanks for all the suggestions - I'll resume after my hols. At least it's watertight for now and I can relax while I'm away.
 
FWIW, another vote here for EPDM. I've done two garden (SIPS) office roofs with it and it's been outstanding.

What does the finish look like? And does it weather well?

This particular roof is very visible from the 1st floor rear windows - it's a large rear extension over the kitchen/open plan area. Paint over GRP/OSB certainly looks smart and I'd like to replicate that sort of finish or something similar.
 

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