Garden room cedar soffit, UPVC fascia and artificial grass on the roof

We are using cedar for the soffit on this job, its western red and a T&G profile, 18mm thick with a 84mm coverage.
The fascia is full replacement black fascia UPVC board and is fixed with polytop nails.
Amy already bonded the rubber roof down previously, so with a quick sweep and clean we are good to fit the artifical grass and secure with Grass fix and also use the rubber roof trims to mechanically hold it too.
I appreciate its not to everyones taste but we like it and so does the customer. And lets face it, its better than looking out onto a massive black rubber roof.
Also we have used flitch beams on the roof, so possibly good for a golfer! Driving range straight down that massive garden.
I can just see it now, suns rising, your in your pants, big cigar, golf club, bottle of something strong...........WHACKKKKKKKKK!!!!!
what could possibly go wrong?