Do we have any acceptance criteria re the gap required around the intumescent painted steel and if we can have timber framing or plasterboard hard against the steel.
I have a response from Nullifire UK as below
In general, a minimum gap of 30mm for up to 60 min and 50mm for up to 120min or 50 x DFT of the intumescent is recommended to allow adequate expansion in a fire.
This obviously poses a challenge as Architects & builders do not consider this requirement which increases the overall thickness of walls where the steel column may be imbedded in. The arrangement of intumescent steel within a wall is generally used to avoid strapping and lining steel to achieve fire protection without increasing the depth of the wall.