Mastic Asphalt

 

Concrete Deck

 One Mastic Asphalt Waterproofing
 two Isolating Felt
 Three 12mm bitumen impregnated fibreboard
 Four Rocksilk Krimpact Flat Roof Slab bonded to vapour control membrane
  Vapour Control Membrane
 Six Sand Cement Screed laid to falls
 Seven Concrete roof deck

Product

The range of Rocksilk Krimpact Flat Roof Slabs are high strength, consistent density, rigid slabs manufactured using the new Krimpact technology, specifically designed for use in flat roofing. The tissue facing recommended for this application controls the absorption of hot bitumen and provides a good bond to resist the effects of wind suction.

Typical Construction

Rocksilk Krimpact Flat Roof Slab and Rocksilk Krimpact Cut-To-Falls are suitable for use on all types of roof deck.

The insulation slabs are laid over and fully bonded to a vapour control membrane which is bonded to the roof deck. The insulation is overlaid with a waterproof membrane consisting of either a fully bonded built-up bitumen roofing system, or mastic asphalt. When used with mastic asphalt, the insulation is overlaid with 12mm bitumen impregnated fibreboard and an isolating felt.

The slabs are not suitable for the direct application of torch-on roofing felts.

 

Installation

The vapour control layer and the Rocksilk Krimpact Flat Roof Slabs are both fully bonded in hot bitumen and then waterproofed.

Built-up felt membranes


High performance bitumen membrane systems are fully bonded in hot bitumen to the Rocksilk Krimpact Flat Roof Slabs using traditional roll and pour methods. Rocksilk Krimpact Flat Roof Slabs are not suitable for the direct application of torch-on roofing felts.

Mastic asphalt surface


Rocksilk Krimpact Flat Roof Slabs provide a stable base for mastic asphalt. The slabs should be overlaid with a 12mm layer of bitumen impregnated fibreboard. A bitumen felt (low grade is satisfactory) should be loose laid without bonding onto the fibreboard prior to the application of two layers of mastic asphalt.

Performance

Standards


Rocksilk Krimpact Flat Roof Slab and Rocksilk Krimpact Flat Roof Slab Extra have been tested to the UEAtc Technical Guidelines MOAT No 50: 1992,

Thermal insulation systems intended for supporting waterproofing membranes on flat and sloping roofs. Rocksilk Krimpact Flat Roof Slab and Rocksilk Krimpact Flat Roof Slab Extra are classified B for mechanical performance – Roof only accessible for purpose of maintenance. May be used without any restrictions.

Thermal performance


The thermal conductivity of Rocksilk Krimpact Flat Roof Slab is 0.038 W/mK.
The thermal conductivity of Rocksilk Krimpact Flat Roof Slab Extra is 0.039 W/mK.

The table below gives U-Values for typical constructions insulated with Krimpact Flat Roof Slab products.

Typical U-values (W/m2K) of flat roofs insulated with Rocksilk Krimpact Flat Roof Slab
 Product  Minimum thickness (mm)  U-values (W/m2K)    
    19mm chipboard, timber joists, 12.5mm plasterboard Profiled metal deck 150mm concrete, 40mm screed, 13mm plaster
Rocksilk Krimpact Flat Roof Slab 180 (100 + 80)   0.18 0.19 0.19
160 (2 x 80) 0.20 0.22 0.21
150 0.22 0.25 0.23
145 0.23 0.26 0.24
Rocksilk Krimpact Flat Roof Slab Extra 180 (100+80) 0.19 0.20 0.19
  160 (2 x 80) 0.20 0.22 0.21
   150 (2x75)  0.22  0.23  0.22
Note: The figures in this table assume a single ply membrane. The U-values have been calculated to BS EN ISO 6946:1997. For project specific calculations contact our Technical Advisory Centre on 01744 76 66 66.

Fire performance


All Rocksilk Krimpact Flat Roof Slab products are classified as A1 to BS EN ISO 13501-1, the best fire performing insulation. The rock mineral wool in Rocksilk products has an extremely high melting point of over 1000°C. In the event of fire they will emit negligible quantities of smoke and fumes. The heat emission from the products is insignificant.

Advantages

  • Significantly improves acoustic performance
  • Non-combustible product with highest Euroclass A1 rating
  • Robust, consistent density solution with consistent compressive strength
  • Can be laid either way up

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