VIEWS COMMENT Get specification right first time

The Metal Cladding and Roofing Manufacturers Association explains the importance of approved cladding systems and the dangers of changing specifications

etal cladding systems provide efficient, aesthetically pleasing and sustainable solutions for a wide variety of external building envelopes. However, the success of these systems can be compromised when specifications are changed under the disguise of ‘value engineering’ by someone who is looking to achieve the cheapest price or maximise profit and source materials and associated components from companies who may not operate to the highest standards.


It is imperative that specifiers have confidence in the capabilities of their chosen suppliers, and it therefore makes sense to specify an MCRMA charter-compliant member company. However, the current economic climate can make it tempting to cut business costs. In an effort to achieve the lowest price, less reputable cladding contractors will source materials and associated components from different manufacturers and then assemble them as a cladding system when it is nothing of the sort. Unfortunately, this results in a system that has no approved

design, no U-value calculation confirmation and no tested fire boundary rating. This raises serious issues for the structural integrity, thermal performance, fire performance and lifespan of the materials and has serious implications for the building owner; in the event of a problem there is no recourse to a sole manufacturer and there is no system warranty.

It is essential in each step of the materials selection process to understand that any one choice of a material type or component does not exist in isolation and has potentially far-reaching implica- tions for other aspects of the performance of the completed building envelope. For example, the effect of thickness (gauge) on the performance of metal systems in building applications cannot be underestimated and the responsibility for not only ensuring that appropriate materials are specified, but selected and used correctly, belongs to all parties within the supply chain.

One of the issues associated with the specification/cost link is the

term ‘equal or approved’. For those downstream of the initial design process it usually provides a loophole to initiate change and perhaps remove an element of cost, remove a degree of quality or improve margins.

Such design changes should not be made in isolation and any proposed change should involve the knowledge and agreement of those at the start of the design chain. Without their involvement or that of the client, a simple and perhaps misunderstood change can lead to disappointment.

Problems are likely to arise when components and materials are sourced from various different manufacturers, assembled and then passed off as a complete cladding system. This is commonly known as ‘pick-n-mix’ and is a conglomerate of incompatible products,


Logistics North Business Park, Bolton – image courtesy of C A Group

brought together to form an assembly, but not a system. This can have serious consequences for the main contractor, cladding contractor, building owner and those involved with subsequent operation and maintenance. For example, the person sourcing the individual items within this construction process will be regarded as the principal designer under the Construction (Design and Management) Regulations 2015 and the ‘designer’ will need to provide PI and/or PL insurance.

These assemblies are put together without any consideration for design constraints, compatibility, long term performance and sustainability, or health and safety issues. This has implications for those who attempt to assemble the parts and those who ratify or condone their use, as subsequent failures will without doubt result in claims and may result in criminal proceedings if negli- gence is a factor.

This approach can show up incompatibilities with guarantees and warranties and also health and safety issues such as ‘fragility rather than non-fragility’ because the system may not have been tested. All these problems can easily be avoided by specifying a fully designed and manufactured system from MCRMA members who understand the needs of the project and who can design a fully engineered system for a specific application. By using an MCRMA charter-compliant company, specifiers


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