EshaTherm PIR B Tapered


EshaTherm PIR B tapered is a tapered rigid polyisocyanurate (PIR) foam insulation for use in bituminous roofing systems on suitable surfaces. As part of a tapered roofing scheme EshaTherm PIR B tapered provides roof surfaces with a finished fall of either 1:60 or 1:80. EshaTherm PIR B is a rigid polyisocyanurate (PIR) foam core faced with bitumen coated glass fibre tissue on one side and polypropylene fleece on the other. The PIR foam core is temperature tolerant and withstands the application of hot bitumen to the surface temperature of 240°C.


EshaTherm PIR B Tapered is compliant with BS EN 4841-4, British Board of Agrément (BBA) certificate number 07/4487.

General information

Uniclass 2015

Pr_25_71_63_66 Polyisocyanurate (PIR) foam boardsPrimary


J41/10 Built-up reinforced bitumen membrane warm deck roof covering

J41/110 Built-up reinforced bitumen membrane warm deck roof covering

J41/115 Single layer reinforced bitumen membrane warm deck roof covering

J41/12 Built-up reinforced bitumen membrane cold deck roof covering

J41/120 Built-up reinforced bitumen membrane inverted roof covering

J41/125 Single layer reinforced bitumen membrane inverted roof covering

J41/130 Built-up reinforced bitumen membrane cold deck roof covering

J41/135 Single layer reinforced bitumen membrane cold deck roof covering

Specification data - Polyisocyanurate (PIR) foam boards

Product Reference

EshaTherm PIR B Tapered


30–200 mm in 10 mm increments. Consult manufacturer's literature for typical U-values.

Standard product features

Product characteristics:

  • Appearance top side: Bitumen coated glass tissue.
  • Core: Polyisocyanurate (PIR) foam.
  • Appearance bottom side: Uncoated glass tissue.

Size (w x l):

834 x 1200 mm.


Typical weight of a 120 mm thick board is 4.1 kg.

Product Options

Technical data:

  • Ozone depleteion potential: Zero.
  • Global warming potential: 3.
  • BRE Green Guide rating: A.

Compressive strength:

Typical compressive strength for the foam exceeds 150 kPa when tested to BS EN 826: Thermal Insulating Products for Building Applications – Determination of compressive behaviour.


PIR foam has a typical density of 31 kg/m³.


The product is stable, rot proof and durable and will remain effective as an insulation system at least as long as that of the waterproof covering. Durability depends on the method of application, the supporting structure and conditions of use. The insulation core and facings resist attack by mould and microbial growth, and do not provide any food value to vermin.

Resistance to solvents (foam):

EshaTherm PIR B resists attack from dilute alkalis and acids, mineral oil and petrol. The foam is not resistant to ketonic solvents. Damaged boards should not be used.

Thermal conductivity:

The thermal conductivity (λ value) of the foam varies by thickness as follows:

  • 25–79 mm: 0.026 W/mK.
  • 80–119 mm: 0.025 W/mK.
  • 120–200 mm: 0.024 W/mK.

Water vapour resistance:

The insulation core has a water vapour resistance of 40 MNs/g/m and will, therefore, provide resistance to water vapour transmission. This will minimize both surface and interstitial condensation. The necessity for the inclusion of a water vapour control layer in the roof construction should be assessed in accordance with BS EN 6229 code of practice for flat roofs with continuously supported coverings.


  • Achieves BS EN 476-7: Class 1 rating for surface spread of flame.
  • Finished with three layer built-up felt and chippings, the roof will attain an FAA rating when tested to BS EN 476: External Fire Exposure Test.
  • Further details on the fire performance may be obtained from Radmat Technical Services.

Roof loading:

Depending on the chosen waterproofing system, EshaTherm PIR B is suitable for use on roof decks that are subject to limited maintenance foot traffic. Walkways should be provided on roofs requiring regular pedestrian access. The roof should be boarded out with protective boarding whenever site work is to take place after the roof board has been laid and the roof made watertight.

Third party certifications

  • 07/4487

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