Vapour Permeable Roof Underlay

  • Integrated tape system for sealing underlay laps
  • Provides a vapour-permeable underlay system with superb wind-uplift resistance
  • Unrestricted usage Zones 1-5, and fully compliant with BS 5534.
  • No need to increase laps to coincide with tile batten courses, minimising cost
  • No need to use an additional ‘fly’ batten to secure laps
  • Printed guidance lines
  • Provides a visual reference to ensure sufficient lap to the British Standard
  • Ensures that the underlay is laid consistently and straight


Marley Universal Vapour Permeable underlay is a high-performance, breathable roof membrane for use in a range of pitched roof constructions.

Complete with an integrated tape system, this underlay provides and effective wind barrier with unrestricted usage across all UK wind zones (BS 5534).

Manufactured using a multi-layer bonding process of polypropylene laminates, the underlay is an ultra-strong, durable, and easy-to-install under-tile layer that is suitable for warm or cold roof applications.

Function & Compatibility

Each underlay is manufactured using the latest materials and processes, and each incorporates a number of useful features that assist in ensuring installation that is not only correct, but also compliant with the latest British Standards.
For use in warm non-ventilated roofs and cold ventilated roofs
For use in cold ventilated roofs
Technical data

Material PP 3 layers
Weight 170 (-10+10)
Resistance to water penetration W1

Batten gauge

<250 (Zone 1-5)

<354 (Zone 1-5)

Adhesive tapes 1
Tests CE, BBA, IBA approved
Tensile strength (N/50mm)
Before artificial aging

MD 400 (-80)

CMD 260 (-50)

After artificial aging


MD > 50%

CMD > 50%

Elongation (%)
Before artificial aging

MD 80 (-20)%

CMD 100 (-22)%

After artificial aging

MD > 50%

CMD > 50%

Tear resistance


MD 190 (-50)

CMD 190 (-60)

Flexibility at low temperature -60oC
Equivalent air layer thickness (Sd) 0,029 (+/-0,01)
Reaction to fire Class E (When tested to EN11925-2

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