Plylok is a high performance rigid polyisocyanurate (PIR) foam board for use in warm flat roofs under built-up felt and approved single-ply membrane waterproofing systems. It is a closed cell, CFC and HCFC-free (zero ozone depletion) rigid polyisocyanurate foam core, faced both sides with a multi-layer coated aluminium foil. A layer of 6 mm WBP plywood is then bonded to the insulation board giving additional strength and rigidity to provide a suitable substrate for partially bonded built up waterproofing systems. The board has exceptionally low thermal conductivity of 0.022 W/mK.

Features/ benefits:

  • Assists in meeting the appropriate Building Regulation standard with any form of warm flat roof construction.
  • Outstanding product quality manufactured to ISO 9001 Quality Systems. All products carry the CE mark to show compliance with the harmonized European Standard BS EN 13165.
  • Zero ozone depletion potential.
  • All Recticel products have a global warming potential of below 5.
  • The declared thermal conductivity value of 0.022 W/mK is some 30% more efficient than most other insulation materials.
  • Fully compatible with most synthetic (PVC, EPDM) and bitumen based single-ply membrane waterproofing systems.
  • No requirement for roof ventilation and inherently safe from harmful interstitial condensation.
  • Condensation within the roof structure is avoided as it is maintained at the same temperature as the inside of the building.
  • Plylok® boards are rot-proof, durable and maintenance free.

Standard product features

Size (board):

2400 x 1200 mm.



Other sizes and thicknesses are available on request. Contact Recticel Customer Services for more information.

Technical characteristics:

  • Specific heat capacity: 1.4 kJ/kgK.
  • Reaction to fire: Euroclass F (BS EN 13501-1); Class 1 (BS 476-7).

Waterproofing systems:

Plylok® boards are compatible with most mechanically synthetic (PVC, EPDM) and bitumen based single-ply membrane waterproofing systems.

- Condensation:

The requirement for a vapour control layer must be assessed with reference to BS 5250 and BS 6229. If required, a minimum 1000 g polythene sheet should be used.

- Roof loading:

Plylok® boards are suitable for loads associated with the pedestrian maintenance traffic on the roof; for areas of heavier pedestrian traffic extra precautions should be taken such as the use of specially designed walkways (consult the membrane manufacturer for specific details). Care must be taken to avoid damage to boards by impact or by concentrated loads during installation.

- Roof drainage:

To ensure adequate drainage the roof should have a minimum finished fall of 1:80. This may mean designing for twice the minimum finished fall to account for building inaccuracies, roof deflection and building settlement.

- Thermal bridging:

With increasing levels of insulation it is vitally important to ensure continuity of the insulation at the junction of elements. At the junction of the roof and the wall packing the eaves with compressible mineral fibre insulation will both prevent thermal bridging and close the cavity. At upstands and parapets the cavity wall insulation should be continued above the level of the roof to ensure continuity of the wall and roof insulation.

- Wind uplift:

The wind uplift force exerted on the roof will vary according to geographical location, site location and building height. Reference should be made to BS 6399 and the membrane manufacturer’s recommendations for the number of fixings and the fixing pattern.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-45-65/430 Polyisocyanurate (PIR) foam board

Product specification

An important note about specifying



Recticel Insulation


+44 (0)1782 590470

Product reference



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Manufacturer details

Enterprise Way,
Meir Park,
Staffordshire, ST3 7UN
Tel +44 (0)1782 590470
Fax +44 (0)1782 590497
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