I'd suggest that the door to the cabin has a vision panel in it and that your fire risk assessment takes into account the change with regard to installing the cabin and using it. I think you'll be covered by section 14 of the RRFSO http://www.legislation.g...005/1541/article/14/made

As always - fire risk assessment. Review and revise the existing assessment to include the "first floor room" as that is what it could be considered to be. No need for fire exit as it is a small enough area, yes ensure the fire alarm can be heard and the occupier in included in evacuation procedure. This will now be an occupied area as opposed to being a storage area so the new use of the area will have to be considered. Fire extinguisher suitable for the risk. Ensure the staircase is suitable for the new use and always maintained free of combustible materials including the underside. Consider the recently introduced Equality Act for the occupants.