Breather Membrane

Class B - EN 13501-1

OBEX CORTEX 0520FR Class B Breather Membrane features water-resistant yet breathable technology, which facilitates the escape of moisture and the prevention of condensation within the external wall construction.  It can be applied to many surfaces including sheathing board, concrete and insulation.  

This breather membrane has a watertightness rating of W1 and is therefore especially suited to demanding applications where the highest levels of water resistance are required.

The membrane is installed using the OBEX CORTEX 0825 Installation Kit which includes 2 rolls of 0824FR Double-Sided Tape and 6 rolls of single sided 0823FR UV Façade Tape.

Typical Uses

  • Class B external breather membrane for use in facades and other construction applications.

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  • 3rd Party Certified 3rd Party Certified
  • 6 Months Exposure 6 Months Exposure
  • Class B Class B
  • EI60 Certified EI60 Fire Test Component
  • Breathable Breathable
  • W1 - EN 13859-2 W1 - EN 13859-2
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Product Specs








Black with white printing

Technical Specs

Harmonised Standard

EN 13859-2

Fire Classification | EN 13501-1


Watertightness | EN 1928


Sd value | EN ISO 12572


Tensile Strength | EN 12311-2

Longitudinal – 255 N/50mm, Transversal - 180 N/50mm

3rd Party Approved

KIWA Approval – BAW-22-245-P-A-UK

UV Resistance

6 Months UV Resistance


OBEX CORTEX 0520FR Breather Membrane KIWA Certificate

OBEX CORTEX 0520FR Breather Membrane Installation Guide

OBEX CORTEX 0520FR Breather Membrane Class B TDS

OBEX CORTEX 0520FR Breather Membrane Class B SDS

OBEX CORTEX 0520FR Breather Membrane Class B DoP

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Product Order Codes

Product CodesProduct DescriptionWidthLengthBox Quantity
20.0520.001OBEX CORTEX 0520FR Breather Membrane - Class B-s1,d01500mm50m 1 roll

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