This RSJ is the ridge-beam in a loft room. Headroom is very tight. Can we glue PIR to it and pink-board and skim over?

All the RSJs I have had anything to do with have been wholly internal and have been fire-protected but have not required insulation. I cannot see any reason why there should be a problem with insulation behind the fire-'slabbing', but having not come across this exact situation before, can anyone see any problems?

Also, on the internal RSJs I have 'slabbed' I was asked once to use 2 x layers of 'pink' fire-board, and other times only one.

What do you think?

Thanks!

''i presume you want to keep it outside the insulated envelope''

Sadly in the circumstances it has to be.

''my under standing was structural elements such a RSJs had to be fireproofed to allow time for escape from each level , 30 , 60 mins etc.
wouldnt everything below the loft room require fireproofing and not the roof above ? ''

That's a valid Q!

I had simply thought that, as steels can 'go' suddenly in a fire, unlike beefy timbers whose degradation can be more easily calculated, it'd still have to be fire-proofed.