Flat roof



Download abrochure:   Flat roof insulation.pdf [450Kb] 


Flat roof is acomplex structure that serves to protect the building against the penetrationof precipitation and moisture as well as to fulfill thermal, acoustic and fireprevention requirements.

This ispossible to achieve by using roof insulation slabs of Knauf Rock rock mineral wool.



  • Increased fire prevention in the building – incombustible material with extremely high melting temperature above 1000˚C, providing a longer fire protection 

  • Excellent technical characteristics from the aspect of compressive strength and tensile strength perpendicular to the surface of material   

  • Reduced heat loss from a room under a flat roof – excellent thermal characteristics provide the required temperature in cold days with reduced heating bills

  • Prevention of the overheating of roof layers under thermal insulation due to sun rays – a more comfortable stay in rooms provided in hot summer days  

  • Dimensionally stable material – rock mineral wool does not change its shape or volume due to changes in the external surroundings 

  • It does not absorb water – a hydrophobic material over the whole cross section  

  • Simple and fast installation – it is easily cut into desired dimensions and shapes


Knauf Rock rock mineral wool slabs may be laid onto a base of profiled steel sheets or onto aconcrete base.




1. Waterproofing (waterproofing foil)

2. Knauf Rock KR Z (KR H)

3. Vapour barrier

4. Layer for equalizing diffusevapour pressure

5. Profiled steel sheet

6. Supporting steel structure 




1. Finishing layer (optional)

2. Cement screed

3. Waterproofing

4. Knauf Rock KR H

5. Vapour barrier

6. Layer for equalizing diffusevapour pressure

7. Supporting concrete structure 



1. Vegetation layer

2. Drainage layer

3. Geotextile

4. Waterproofing

5. Knauf Rock KR H

6. Vapour barrier

7. Layer for equalizing diffusevapour pressure 

8. Supporting concrete construction 


Recommendationsfor designing and construction:

  • The most frequent causes of damages to roof structures, particularly with old buildings, result from improperly designed layers of a flat roof structure, use of inappropriate materials, faults in the construction of details and installation of thermal insulation material with insufficient thickness; at designing, therefore, thermal insulation thickness should be determined in accordance with the requirements of technical regulations, while at construction it is important to carry out properly all details related to attics, cupolas and other places where waterproofing penetration occurs (all in accordance with the instructions of the waterproofing manufacturer), in order to ensure full functionality and insulation stability of the flat roof

  • During construction works, thermal insulation material should be protected against the penetration of precipitation whether by installing daily only as much thermal insulation as may be covered and protected by waterproofing, or by providing a temporary protection of the material in any other way.


 Advice for proper use