Gary Robson, Business Development Manager at EJOT UK, highlights the important role of substructures in façade systems.
Rainscreen systems or rear ventilated facades have a critical role to play in transforming the performance of buildings and ensuring that renovation and conversion projects meet today’s more stringent compliance requirements.
Correctly designed, specified and installed, these systems can give buildings a sustainable new life within a lower-carbon built environment. However, achieving their full potential depends on all substructure components delivering assured quality and performance.
Maximising thermal performance
Substructures make a significant contribution to the overall insulating capacity of a façade. While aluminium brackets and rails have traditionally been favoured for rainscreen systems, this type of metal is known for its greater heat conductivity compared to stainless steel. This is one of the key reasons why the latter is used to manufacture the Konsole brackets used in the EJOT CROSSFIX system.
Across a façade, the cumulative effect of hundreds of brackets can create significant thermal bridging. Switching from aluminium to stainless steel brackets, therefore, can cut heat loss substantially, allowing for reduced insulation thickness or a lower overall U-value to be achieved without increasing insulation depth.
Minimising fire risk
Stainless steel substructure components can also offer fire performance advantages over aluminium because they retain a higher degree of mechanical strength at high temperatures. In addition, the non-combustible CROSSFIX system is Euroclass A1 classified for reaction-to-fire according to EN 13501-1, signifying that it will not contribute to the spread of fire.
The integration of open state and closed state cavity fire barriers is also important to reduce the risk of fire spreading through the cavity and it is essential in many projects. To ensure this is done in line with manufacturer recommendations and the building’s life expectancy, the correct type of fasteners must be used. The options available in the EJOT range of bi-metallic and A2 or A4 stainless steel fasteners can accommodate all cavity barrier fixing requirements.
Compatibility with multiple building substrates
Given the huge variation in construction styles, particularly those which have been extended over time, substructures in refurbishment projects often have to work across numerous different substrates. This is an important advantage of the EJOT range spanning everything from the backing structure framing, profiles, brackets, fasteners and fixings, all supported by substantial test data with many also independently certified with European Technical Assessments (ETAs).
Providing structural integrity
A final design objective for the substructure is to ensure it withstands the various loads that the façade will be subject to throughout its design life. Specifying a complete subframe system such as CROSSFIX can simplify verification through the calculations and test evidence provided in its ETA. This system also offers a high load capacity, which can be advantageous where substrates have variable strength or for heavier rainscreen materials such as natural stone and precast concrete.
For more information on EJOT’s façade substructure solutions call +44 (0)1977 687040 or visit www.ejot.co.uk.
