Thermal insulaton

Stone wool offers superior thermal insulation properties

Thermal insulation is a measure of how easy heat is being conducted through a material. The thermal insulation value is a combination of thermal conductivity, measured according to norm EN12667 and the thickness of the material. Conductivity (l) is expressed in W/mK. The smaller the l-value, the better the thermal insulation of the material. A material can be definied as thermally insulating, if the l-value is smaller than 0.060 W/mK.

The thermal resistance value as a unit area of the specific layer of material (e.g. the ceiling tiles) is expressed in R. It can be calculated as follows: R = m/l (in m²K/W) in which m represents the thickness of the material (m) and l represents the thermal conductivity of the material.

There are building situations where the thermal insulating properties of ROCKFON stone wool ceiling tiles can be very beneficial.

Typical examples of this are shopping malls built over parking garages, flat-roof buildings or old buildings with cold cellars.

In those situations, the relevant ROCKFON solutions need to be seen as part of the total thermal insulation solution taking into account building physics (e.g. condensation, avoiding thermal bridges, etc).

Product comparison on thermal conductivity
Standard ROCKFON ceiling (20mm)0.037 W/mK
Wetfelt0.052-0.057 W/mK
Gypsum0.230-0.460 W/mK
Gravel concrete1.300-1.900 W/mK

Overview of R-value (in m2K/W) as a contribution to Rc-value
of some commonly used ceiling tiles
Standard Rockfon ceiling (20mm)0.54
Sonar Activity (40 mm)1.00
Wetfelt (18 mm)0.33
Gypsum (12 mm)0.04


ACERMI is the French certification for materials and products for thermal insulation of buildings. ACERMI certifies thermal performances of products and prove their durability. It allows end users to choose products on the basis of reliable criteria (comfort, performance, safety…).


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