Pitched roof



If you want tomake an attic a comfortable and safe living place, the roof structure mustoffer the following to the user:

  • Protection against cold in winter and against heat in summer  

  • Fire prevention as the roof structure is mainly constructed of timber  

  • Acoustic protection against noise that surrounds us.


All of theseare possible to achieve by using Knauf Rock NaturBoard FIT or NaturBoard FIT PLUS rock mineral wool insulation.

From the aspectof increased energy efficiency and durability of the whole system of a roofstructure, it is important to fill the space between rafters with Knauf RockNaturBoard FIT or KR SK rock mineral wool ofappropriate thickness depending on the climatic zone in which the building issituated. For covering thermal bridges, rafters in this case, Knauf Rock NaturBoard FIT or NaturBoard FIT PLUS rock mineral wool slabs are placed between supports of the substructureof the internal space final lining.


  • Reduced heating bills - excellent thermal characteristics prevent heat loss and provide energy efficient construction  

  • Prevention of overheating of the attic in summer – higher density of rock mineral wool provides higher accumulation of heat and reduces the need for air conditioners

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

  • “Breathing” of the construction and undisturbed vapour permeability – owing to open porosity of the material  

  • Acoustic protection provided – excellent absorption material  

  • There is no distortion or sinking of insulation material – a durable stability of dimensions in the system is provided

Simple and fastinstallation – the self-supporting effect is obtained by cutting the slabs 1cmwider than the light width of rafters.



Proper insulation of a roof pitch comprises theformation of a ventilated air layer above thermal insulation material throughwhich moisture is taken out in winter and hot air is eliminated in summer.Depending on the roof structure, ventilation may be as follows:




indirect: it is carried out with the use of lathslaid longitudinally along rafters – a lath roof structure:


  • Roof covering (tiles)

  • Laths and counterlaths

  • Vapour permeable-waterproof foil




direct: by leaving an air space under theboarding, next to insulation material – an under-boarding structure:


  • Roof covering (e.g. shides)

  • Waterproofing (bitumen strips)

  • Boarding

  • Ventilated, air layer.




When a roofstructure is finished, insulation of the pitched roof is carried out in phases: 



  • 1. In order to achieve thermal, fire and acoustic protection as defined bythe standard, Knauf Rock NaturBoard FIT or NaturBoard FIT PLUS rock mineral wool slabs should beplaced between rafters; in order to provide a quality insulation, the slabsshould be laid close to each other, filling the entire space between rafters: alongthe rafter width (slabs should be cut 1cm wider than the light width of rafters)and along the rafter height (do not leave air “pockets”); rock mineral wool slabs should be cut into triangles in order to reducewaste


  • 2. Install supports of the substructure of veneer base in accordance withthe manufacturer’s instructions 
  • 3. Place an additional insulation layer under rafters, Knauf Rock NaturBoard FIT rock mineral wool slabs betweenthe substructure supports


  • 4. Place a vapour barrier by sticking it to a strip which is self-adhesiveon both sides and which was previously glued in spots along the substructure 
  • 5. The roof pitch should be lined with veneer base; finishing should becarried out in accordance with the purpose of premises, as well as inaccordance with the instructions of the veneer base manufacturer. 


Notesabout installation:



All foil jointsmust be carried out with overlapping and the overlaps should be glued withadhesive tape; foil penetration spots should be glued in the same manner; thisapplies for both foils: the vapour barrier and the vapour permeable andwaterproof foil.

Properventilation of the roof is obtained by properly carried out constructiondetails that will provide undisturbed flow of the air layer above theinsulation material, from eaves to ridge. 





Ifyou have already made your attic a comfortable living place but insufficientlywarm in winter and too hot in summer, you may have an additional insulation of KnaufRock KR H rock mineral wool placed on the external side of theroof structure. 



Thereconstruction should be carried as follows:


  • Remove the roof covering and laths  

  • Remove the secondary roof covering, if any – with old buildings it is often a bitumen roofing paper  

  • Place Knauf Rock KR H rock mineral wool slabs over rafters, externally

  • Place vapour permeable and waterproof foil over the rock mineral wool slabs; stick all the overlaps with adhesive tape  
  • Place counterlaths andlaths upon which roof covering should be laid (e.g. tiles).