it would cost too much, special tiles to protect the flat roof below, and railing all the way round (aprox 30ft long) would be excessive, let alone fixing it to the roof without damaging the membrane. Though in answer to Project, the flat roof was overbuilt (wood work wise), with the intention of possibly using it as a balcony.
Basically I couldn’t charge anymore either as the view is onto a tatty estate behind (this is Brum after-all), it more about being able to open the french windows during the summer, as the side windows only have small top openings.
Anyways I’m pleased with Wwaswas’s suggestion, as a short section of railing won’t cost a lot & be easy to install. That and I can’t see anyone being able to say I didn’t try to stop access through/out the window