Our recommended solution would be the use of a Promat Supalux® ceiling system, for fire ratings of up to 120 minutes load-bearing capacity, integrity and insulation. The fully tested and certified arrangements for most variants of the system include the use of non-combustible stone wool type insulation above the line of the Supalux® ceiling lining boards, with a stated minimum density and thickness required for the fire performance element of each. For any systems which don't require the use of stone wool insulation, additional non-combustible lightweight glass wool insulation can be easily incorporated into the construction in addition to the standard, required elements, with no compromise to the fire performance. For any standard systems requiring the use of rock wool insulation to achieve the fire performance, additional non-combustible lightweight glass wool insulation can be applied above the line of the rock wool insulation.

It should be noted that the calculated weight per square metre of insulation for the ceiling will then be above that for the tested system, so you should check to ensure that the maximum flexural strength of the Supalux® boards, at 4.5N/mm², isn't exceeded.