GRP flat roof repair options

[Hajj]

Hi folks! I am writing as yet another victim of the national scandal of GRP flat roof installations. My GRP flat roof started leaking after a couple of years of installation, with damp patches appearing on interior ceiling. Some areas on the roof were patched up but now another leak has occurred so I get the impression the entire roof needs re-doing.

I have searched the forum and there are some interesting relevant posts as I am not the first to have experienced this problem but I have a slightly different take and would appreciate some views please.

The conclusion I have reached is that GRP flat roofs are too difficult for non-specialists to install (e.g. general builders). Even the Cure-It training video on YouTube says at 12 mins 39 secs that you should check for pin holes when applying the resin otherwise this will lead to permeability! I am thinking which overworked underpaid builder's apprentice or manual labourer working on a roof at the end of the day/week is going to get this vital step right!

Check it for yourself!

Any way, this poll is for a flat GRP roof, say 4m x 4m with one sky light ... nothing too complex or with extreme weather conditions or being home to dancing elephants etc. etc.!

My dilemma is as follows:
- it makes sense to recoat the GRP as it means trims and flashing will not need re-doing and if the hull of a boat has a problem, you don't end up doing the entire hull again ... so a patch repair or resurface should work
- but on the other hand if the GRP system is problematic best to quit now and go for something more proven
- if I am going to recoat then might as well go with liquid rubber rather than fail-prone GRP
- on the other hand felt is tried and tested and a favourite of roofers, and even better, EPDM comes made to measure so has no seams

 

[Alastairreid]

Have a look at Lava 20.

 

[Rufus Raintight]

When you say patched up the first time, what did they use? More GRP or some other product?

 

[Hajj]

More GRP

 

[Rufus Raintight]

Don't use Acropol, it's not a long-term solution, only really used for emergency patch repairs. Felt and EPDM would fix the problem but it's an expensive solution.

The cheapest option as you have said in your post would be to either locate the areas (pinholes) on the roof where it's leaking and patch it with more GRP or encapsulate the entire roof with another liquid system. I would either go for polyurethane or some of the new hybrid products that don't need a primer or reinforcement. If you are getting a contractor in to do this then they should already know a suitable product but if you're doing it yourself let me know and I'll recommend some products.

 

[Hajj]

Thanks @Rufus Raintight , that would be great if you could recommend some products please. I have spoken to a few roofers now and they are all keen to re-do the entire roof with torch-on felt or EPDM ... it seems like that's what they know how to do and they can be sure it will last.

I thought patch up might be a bit hit and miss ... if I miss a tiny pin hole then I have to patch up again ... I'd rather implement a sure 1-off solution to keep me going for 10+ years.

I thought of applying a liquid product but then why not just go for a single sheet of EPDM? Surely, a factory made sheet of rubber is better than one applied on site.

 

[Notch7]

rather than fail-prone GRP

I wouldnt say GRP is fail prone, I used it all the time for orangery roofs, but like anything it has to be done correctly

I liked it orangery roofs because they can have lots of different falls and changes in direction so GRP is ideal

however its biggest failing is you have to have dry weather when doing the resin and again when doing the gel coat -for a few hours until it sets. Not always easy in our climate

Thanks @Rufus Raintight , that would be great if you could recommend some products please. I have spoken to a few roofers now and they are all keen to re-do the entire roof with torch-on felt or EPDM ... it seems like that's what they know how to do and they can be sure it will last.

I thought patch up might be a bit hit and miss ... if I miss a tiny pin hole then I have to patch up again ... I'd rather implement a sure 1-off solution to keep me going for 10+ years.

I thought of applying a liquid product but then why not just go for a single sheet of EPDM? Surely, a factory made sheet of rubber is better than one applied on site.

more roofers are used to felt or EPDM than liquid roof systems

I did my garden office with a EPDM myself, its about 5m x 4.5m and its been 100% watertight for the 5 years Ive had it, and Ive been up there and it all looks spot on still. The only thing I dont like is it gets unbelievably hot in the summer and it starts to smell of rubber.

I personally think if you are going for a liquid system, use an approved contract from one of the manufacturers......they only sell to their network of approved contractors.

 

[securespark]

I had a complete and utter cockwomble do our flat roof in GRP. It leaked mostly because he hadn't bothered to deal with the soil pipe so water flooded in.

We had it covered in board then rubber on top. And the soil pipe was sealed effectively.

So I vote rubber.