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Polyfoam Roofboard Standard

Insulation Products: Roofs > Flat Roof Insulation

Product Code: 22521

Polyfoam Roofboard

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Product Description:

For the thermal insulation of flat roofs


Polyfoam Roofboard is a high performance, 100% ozone friendly, extruded polystyrene, rigid board insulation. It is lightweight, yet has excellent structural strength and long term effectiveness. Polyfoam Roofboard is available in three grades to suit the intended end use of the finished roof:
  • Standard – Light to occasional maintenance traffic loading
  • Extra – Consistent loading and plant loading, pedestrian traffic loads.
  • Super – Very high loading, car parking and heavy traffic loads,
Polyfoam Roofboard is supplied with interlocking rebated edges. Polyfoam Foil Faced Roofboard is supplied for single ply membrane roofs where a separation layer is required.


Polyfoam Roofboard is used for the thermal insulation of flat roofs. If a lower strength insulation is used the potential uses of the roof space are limited and potential future use is also difficult. Increasingly, the optimum roof insulation has to:
  • have both thermal potential AND structural strength
  • be capable of bearing future change of use as well as offering a wide variety of design options for the use of the actual roof area
  • be a good thermal performer
  • be structurally stable in the long term
  • be lightweight
  • be easy to install
For protected membrane roofs the combination of strength and very low moisture absorption are key performance requirements. The following range of applications are some of the key areas of use of Polyfoam Roofboard: Protected membrane roofs for:
  • Schools, Hospitals and other public buildings
  • Offices
  • Retail developments
  • Industrial developments
  • Green/garden roofs
  • Roof terraces and patio areas
  • Roof top car parks
Polyfoam Roofboard is suitable for almost any roof construction including:
  • Under concrete for a roof top car park
  • Under gravel ballast in a protected membrane roof (on concrete, metal or timber deck)
  • Under paving slabs for a terrace area in a protected membrane roof construction
  • Under growing matter in a green/ garden roof
  • In a Single Ply Membrane roof


Compression resistance
All materials are compressed under load. If the roof is going to be transformed from a limited access waste of space into an interesting and useful space the insulation must be capable of accommodating applied loads. Polyfoam Roofboard is highly resistant to compression and withstands both occasional and long term static loads. A factor of safety for design loads of 3 (5 for long term static loads) is applied to the compressive strength of the product as outlined in the product data tables.

Moisture resistance
As can be seen in the attached detail drawings, in many applications Polyfoam Roofboard is above the waterproofing layer and thus exposed to rainwater. The board is resistant to moisture absorption and can be laid in standing water or up against wet concrete with minimal impact on the performance of the product.

Thermal insulation
Polyfoam Roofboard is a high performance insulant, with aged quoted thermal performance values. The actual performance in use of each grade of Polyfoam Roofboard is outlined in the attached application sections.

Fire Performance
When Polyfoam Roofboard is installed in a roof construction it will not contribute to the development stages of a fire.


Polyfoam Roofboard Standard, Extra and Super are 3rd party certified by the British Board of Agrément.

Handling and storage

Polyfoam Roofboard is supplied in polythene packs, labelled with identifying product and manufacturing data. The boards are easy to handle and non-irritant, no special protective clothing is required to install them. Polyfoam products should not be left exposed to prolonged sunlight as this will result in surface degradation. Where outside storage for extended periods is required cover with opaque/light coloured sheeting. Ensure the boards are not stored close to open flame or other ignition source, also avoiding volatile compounds and chemicals such as solvents.

Product Data

All Polyfoam Roofboard products have a moisture absorption of 0.20% by volume and continuous service temp. limits of -50°C to +75°C

Click on the Sub Code for more details.

Sub Code
1250 mm
600 mm
50 mm
1250 mm
600 mm
60 mm
60mm Foil Faced
1250 mm
600 mm
75 mm

Other Products By This Manufacturer: Knauf Insulation Limited

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