Low Pitch Waterproofing

[PaddyP]

Hi all, 

 

We are just finishing off the roof structure here and hit a bit of a bump in the road. The house is split into two blocks each with a 5° monopitch roof. We had wanted to put a metal standing seam roof on however had struggled to find a supplier that would a. give a guarantee at 5° b. could roll 20 metre lengths required for the roof c. would not cost the moon and stars. I eventually did find a supplier but now unfortunately this has fallen through so am exploring other options. 

 

The roof structure is Thermoroof insulated panels, 50mm battens for ventilation and decked in 18mm OSB. The options I appear to have are as follows:

 

Fibreglass/ GRP: always appears to be highly recommended on the forum here. From research only appears to be as good as the installer. Where I am in the South East of Ireland not the most popular choice and installers are lacking so not my first choice. 

 

Single Ply Membrane: mechanically fixed to the roof. Soprema and Trocal are some of the brands used by installers here. One Trocal installer visited the site and said he spends most of his time on repairs these days which has sent alarm bells ringing. 

 

EPDM Rubber Roofing: Firestone is the only real option for this here. Single sheet glued down appears to be fairly highly regarded with a 25 year warranty and expected lifespan Of 50 years plus. 

 

To me the Firestone EPDM appears to be a clear winner. Reasonable price, long lifespan and reasonably robust. Is there anything I'm missing here? Is there downfalls to EPDM I'm not aware of or any horror stories? 

 

Thank you very much for your help!