Architects, with their extensive knowledge in sustainable construction, often draw on specialist advice, such as from AFA members, to ensure that the final design of any project meets the clients requirements exactly. Unfortunately, when a project eventually does go out to tender, the dreaded terms such as ‘equal or equivalent to’ are jumped upon to look at reducing costs to secure the project. One of the major areas of concern for a change in specification, are surfaces which are open to the elements, such as building envelopes and in particular, the architectural aluminium finishing.
Architectural powder coating will be clearly specified at the time of design, such as manufacturer, colour and applicator, for all the metal components within the building envelope. Unfortunately, what often filters down through to orders does not always meet the specification. Using the ‘equal or equivalent to’ can often mean that differing manufacturers’ powder and pretreatment systems are used side by side and, as a result, often exhibit an obvious shading difference.
Richard Besant, Sales Director of AFA member, Powdertech (Corby), takes up the story. “The building envelope is rarely fabricated and installed entirely by a single contractor and as a consequence different elements from different sub-contractors end up at a variety of metal finishers, all using different pre-treatment processes and various makes of paint or powder. Even a single subcontractor may use different coaters as a pragmatic decision in order to meet delivery deadlines. As a short-term fix, meeting the deadline may well be achieved but problems are stored up for the future and usually come back to bite. These problems result from the ill-defined specification for the final layer of the building envelope – the metal coating or finish. A loose specification allows different sub-contractors and coaters to interpret it differently. Some may go with a make and shade of powder that has been named, but others may indeed go for what they believe is ‘equal or equivalent to’. Even if a particular RAL colour is adhered to, the exact shade can differ between the versions from different manufacturers. A good example is metallic silver – every manufacturers version is slightly different. Of course you wouldn’t know this until they end up in close proximity.”
In the future, BIM may be the answer, with a more rigourous specification for metal finishing being built into all the individual components of the building design. As a result architects and clients should see the same powder manufacturer, colour and applicator used for all components. Through the adoption of BIM, the building industry may at last have found a route through which difficulties are eliminated at the outset.
The AFA encourage specifiers and contractors to insist on the early selection of a single AFA applicator for all architectural aluminium finishing on a project to ensure consistency and quality of finish. More information on the AFA and its membership can be found on the associations website at www.afauk.org.uk.