Cheers Ralf, has seen those.
My challenge is the 500C heat coming out the top of any chimney so close to the woven nylon awning.
There's the patch from low & slow / the odd pizza that's already ruined the waterproofing, so assuming a chimney being closer would make it far worse.
Always a fear on the BGE is not burping it when running hot, creating a flashback that sears me on the way up, then melts the awning & sears me on the way back down!