You do not say if your slates are hook fastened or nail fastened also which is the original company that supplied the slate, If you can supply the answers it will make your question easier to answer
And I do not care what you say , what qualification do you have apart from an email address and total lack of knowledge ,for EPDM read tarpaulin , or rubber condom. the detailing is where that system breaks down. I can find a lot of good Flat Roofing companies that have been going for many many...
Got to agree with you on EPDM , and GRP got to disagree on not using thermal movement layer check Andersons Icopal specification (to name but a few) both have SBS felts both specify thermal movement layer
Such a pity I read this late but for future edification the guy that said three layers........ was correct, the first is a thermal movement layer this prevents the felt from being fully bonded to the decking and allows movement , I would advise you to check with the NFRC, Then look at the...