When considering the specification of the insulation element of Promat's ceiling systems, the following statement is given the within the Promat SUPALUX® independent 3rd party certificate, Certifire CF420:

“Alternative thicknesses and densities of stone wool insulation may be fitted provided that the weight per square metre is at least that specified and that the percentage of binder content by weight does not exceed that of the insulation fitted in the tested constructions.”

If you wish to improve the thermal performance of this type of system, there is a simple calculation method which can be used to determine what alternative insulation specifications can be used, noting that any stated requirements for the insulation in terms of numbers of layers and staggers between layers must still be adhered to.

Example:

60 minute SUPALUX® new ceiling lining to timber joisted floor constructions, Method 1, with a standard stated insulation requirement of 30mm x 60kg/m3

If additional thickness of insulation is required in order to meet thermal performance figures, say 50mm, the minimum density of this insulation can be calculated as follows:

(30 x 60) / 50 = 36kg/m3

If the density of the proposed insulation is 120kg/m3 the minimum thickness of this insulation can be calculated as follows:

(30 x 60) / 120 = 15mm