Following the introduction of the Building Safety Act, it is now essential that everyone understands the performance standards that are required for an ISM (Interface Sealing Membrane) to be compliant with the Building Regulations.  A membrane that is used for sealing around window frames and along facade interfaces must conform to EN13984. 

So what is EN13984?

EN 13984 is the European Harmonised Standard that outlines specifications for Interface Sealing Membranes used in construction.  Compliance with this standard is essential for ensuring the quality, performance, and durability of these membranes, used to effectively seal interfaces on facades and around windows, preventing water ingress and maintaining the integrity of the building envelope.   

It includes specific standards for properties such as water tightness, water penetration resistance, fire-classification, etc., as follows;

EN 1928 – Water Tightness  

This standard ensures that an Interface Sealing Membrane will perform its primary function, i.e. water tightness. An ISM must pass this test to be compliant, which involves being subjected to 2kPa of water for 24 hours. This is essential as without compliance, over time water may penetrate the façade causing legacy issues. 

EN 13501-1 – Fire Classification 

Interface Sealing Membranes that form part of an external wall on relevant buildings over 18 metres tall must have a minimum fire classification of B-s3,d0 according to Approved Document B.  However, Regulation 7 requires all elements to achieve Class A.   

The main part of the classification shows a letter – A1, A2, B, C, D, E and F, with A1 (non-combustible) being the highest level of performance.  s1, s2 or s3 is a smoke classification, with s1 indicating the least amount of smoke, while d0, d1 or d2 shows the level of flaming droplets with d0 being the highest level of performance. 

Class A Interface Sealing Membranes are now available and should always be used where possible. 

EN 1931 – Water Vapour Transmission

EN 1931 specifies a method for the determination of the water vapour transmission properties, the calculation of the density of moisture flow rate g, and of the moisture resistance factor µ of Interface Sealing Membranes.

EN 12310-1 – Resistance to Tearing

This standard specifies a method for the determination of the ‘nail shank’ tear resistance of ISM’s and is tested in both directions.

Exceeding the Standards 

Compliance with all of these standards must be achieved to contribute to the overall Harmonised Standard of EN 13984. The OBEX Interface Sealing Membranes pass these specific testing standards, with products available to suit every requirement.