We are having a loft conversion done, and are going down the submitting full plans to building control route.
The project is mainly DIY with assistance from a structural engineer.
The property is a 1030's end of terrace with the stairwell leading straight down towards the front door . The hall has a door off to the front room, and a door to the back (dining) room. The problem we have is creating a fire rated protected stairwell as the wall between the staircase and the back room is original 1930 tongue and groove boards approx 22mm thick. These are supported top and bottom with additional fixings into the side of the stair.
The boards continue down to create an understairs cupboard.
Obviously, the T&G will need to be uprated to achieve a 30 minute fire rating, but does anybody have any experience of what is required? Local Building Control where very helpful on the phone, but they (and us!) are at a bit of a loss with how to comply without ripping down the wall and put up new studwork with 12.5mm plasterboard both sides.
Ideally we would like to keep at least one side of the boards showing.
Any ideas?
BTW, we are getting the new staircase made to measure from Stairplan, we have found them very helpful and would recommend them to anyone else having a conversion. Price is very reasonable - under half the cost of all the insulation required!
Paul real is pjw at ntstelcom#co#uk