Permavent APEX

Permavent APEX

Permavent APEX is both an air and vapour permeable membrane for use as a pitched roof underlay.


Permavent APEX is a 3 layer air and vapour permeable membrane, providing unique condensation control which eliminates the need for low or high level ventilation. APEX also provides a secondary barrier to water ingress.

Permavent APEX is fully compliant with BS 5534:2014+A2:2018 Code of practice and an integrated double tape system allows APEX to be installed in all UK wind zones. An untaped option is also available.


  • Air and vapour permeable membrane
  • 180 g/m2
  • Integrated tape (25% less membrane usage)
  • Use without ventilation
  • Conforms to BS5534:2014+A2:2018
  • Fully BBA certified
  • 3 layers membrane
  • For use on any types of roofing/walling applications
  • UV stable for 3 months
  • An untaped version is also available
  • Available in 1m x 50 rolls taped; 0.5m x 50m, 1m x 50m and 1.5m x 50m rolls untaped


Fully Air Permeable
APEX air permeability allows moisture to escape through the movement of air, which eliminates interstitial condensation in pitched roofs. This can be particularly important during the drying out period of a new build.


Vapour Permeable

Permavent APEX vapour permeability helps to reduce the condensation withing the roof structure, whilst protecting it from the rain and wind outside until primary barriers are installed. Permavent APEX has Sd value of 0.01m.


Water Resistance

Permavent APEX is highly water resistant with a W1 rating (EN 13589).


BBA Certification

Permavent APEX has full BBA Certification for use in both cold and warm non ventilated roofs.


Compliant with BS 5534: 2014 + A2 2018 Code of Practice

Permavent APEX is fully compliant with BS5534:2014+A2:2018 Code of Practice and our taped version can be used in all UK wind zones without the need for high and low level ventilation.


Integrated Double Tape System

Permavent APEX is available with a unique integrated double tape system. This ensures that the laps of the membrane are restrained in any weather condition using a 100mm head lap and meet the BS5534:2014+A2:2018 Code of Practice standard. This can reduce membrane usage by up 25%.


Weight, g/m2180
Water tightness, classW1
Water vapour transmission (sd), m0.01
Maximum tensile force (MD), N/50mm330
Maximum tensile force (CD), N/50mm270
Elongation at max. tensile force (MD), %56
Elongation at max. tensile force (CD), %68
Resistance to tearing MD (nail shank), N210
Resistance to tearing CD (nail shank), N210

UK Wind Zones

Taped Lap1-5
Batten Lap1-3
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