Why are brick support angles manufactured from stainless steel?
This is a question Ancon’s Technical Services Team is regularly asked by those specifying and purchasing support systems for masonry cladding. Here, we outline the reasons why stainless steel is used in this application.
The relevant codes with regards to material specification are: BS EN 845-1, BS EN 845-2, and NCCI document PD 6697:2010. Table 2 of PD 6697:2010 states that for buildings exceeding three storeys high, material selection should be limited to austenitic stainless steels for bracketry, lintels and ties in contact with or embedded within an external leaf of a cavity wall.
For buildings up to three storeys high, materials may be selected as per this table and its accompanying notes. The table states that for components in contact with or embedded within an external leaf of a cavity wall, components should be made from either austenitic stainless steel or steel which has 930g/m2 zinc coating.
If the product is galvanised it would require the maximum possible thickness of zinc coating. The coating could get chipped or damaged during transit or installation, which compromises the protection. Furthermore our advice would be that some sort of inspection regime would be required throughout the lifespan of the building.
Whilst the code does allow the use of steel with very thick galvanised coating, it is important to remember that masonry support angles are structural elements which are very difficult (sometimes impossible) to inspect and exceedingly difficult and costly to replace during the lifespan of the building.
Therefore, Ancon advises that austenitic stainless steel be used in all masonry support systems, as this ensures that no corrosion issues arise and no remedial work would be required in the future.
As they cross the insulated cavity, the thermal conductivity of support angles should also be considered. Stainless steel offers significant thermal efficiency benefits over galvanised steel, improving the performance of the building envelope.
Contact Ancon for advice on the design of support and restraint fixings for brick, block or stone cladding and for more information on the types and grades of stainless steel used by the construction industry.
Designed to minimise thermal bridging in masonry cavity walls, the patented Ancon Thermal Windpost (TWP2) from Leviat offers up to an impressive 70% reduction in thermal transmission through the span of the windpost.
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