With the introduction of The Building Safety Act in 2022, it is vital that everyone understands the performance standards that are required for construction membranes to be compliant with the Building Regulations.

A Breather Membrane’s primary function is to prevent water ingress into the façade of the building whilst at the same time allowing water vapour to escape.

EN 13859-2 is the European Harmonised Standard that details the characteristics, requirements, and test methods of Breather Membranes in faҫades.

Within the overall standard of EN 13859-2, there are a number of standards that the Breather Membrane is tested for, including water tightness, water vapour transmission, resistance to air penetration, tensile strength, etc.

EN 1928 – Water Tightness

This standard indicates a Breather Membrane’s ability to resist water penetration at a pressure of 2kPA for 2 hours, in order to achieve W1 classification.

EN 12114 – Resistance to Air Penetration

Breather membranes prevent the passage of cold or moist air into the building fabric from outside, for which a Resistance to Air Penetration of <0.3 m3/m2/hr@50Pa when tested to EN 12114 is required.

EN ISO 12572 – Water Vapour Transmission

This standard specifies a method for determining the water vapour permeability of Breather Membranes under isothermal conditions.

EN 13501-1 – Fire Classification

The Building Regulations stipulate that all elements of the building envelope on a relevant building need to meet minimum Class B-s3, d0 fire classification. 

Class B indicates very limited contribution to fire on the scale of A1 (non-combustible) to F (easily flammable), s3 relates to the level of smoke emission and d0 indicates no burning droplets.

Class A1 and A2 Breather Membranes are readily available and are the preferred option for many contractors and specifiers.

EN 12311-1 Tear Strength (Nail Shank)

This test measures the resistance of the membrane to tear.   This is an important consideration if, for example, the membrane could be subject to penetrations or high winds.

EN 12311-2 – Tensile Strength

Breather Membranes are tested to EN 12311-2, to determine their tensile properties both longitudinally and transversally. 

Five tests in each direction are carried out.