A specifiers guide to building boards in cladding applications

Ian Quinton, managing director of RCM – suppliers of building boards and facade solutions to some of the UK’s most prestigious developments – outlines the key criteria to consider when specifying building boards and cladding solutions.

In order to select the right product for the right application, you need to be supplied with the right technical information, not a glossy, uninformative brochure. As design professionals you require robust, well-researched and certified technical information, including classification, performance and installation details. Simple but so very often overlooked.

The NBS National BIM Report 2014 reveals that 90 per cent of specifiers find product inclusion in NBS BIM useful – they of course would say this, however, as one of the few build- ing board suppliers to use this specification system – RCM is a great advocate. Product information authorised by NBS enables professionals to specify with ease – crucial in early stage concept calculations and specifying decisions.

Even when specialist advice is available, a working knowledge of regulations and performance is fundamental to making the right specification decisions – here are just six key points for consideration.

Technical approval

Specifying systems with a credible certification provides reassurance and confidence to specifiers. BBA, for example, offers full technical approval for construction products and is recognised by building control, government departments, architects, local authorities, specifiers and building insurers. BBA Approval provides architects, designers and contractors with certified information when specifying or installing building board products.

Approval includes:

  • Factors relating to compliance with Building Regulations
  • Factors relating to additional non-regulatory information
  • Independently verified technical specification
  • Assessment criteria and technical investigations
  • Design considerations
  • Installation guidance
  • Regular surveillance of production
  • Formal three-yearly review
  • A generic standard for the evaluation of building boards to also consider is BN EN13986 2004, which explores characteristics, conformity and marking for use in construction.
  • Structural strength and stability

A significant consideration when assessing building boards is to ensure the optimum racking performance to enhance structural strength. For example, European norm – BS EN 594:2011 – is the recognised testing protocol for testing racking strength and stiffness of timber frame wall panels. Building boards and cladding systems with BS EN 594:2011 certification have been rigorously tested and offer good racking, performance, structural strength and stability.

Another factor to consider for stability is moisture movement. When evaluating a solution, consider a system that offers a high level of dimensional stability with limited moisture movement. Building boards can be specified with as little as 0.06 per cent moisture movement.

Resistance to moisture and durability

By specifying a building board that is fully tested to BS EN 1062-1, it ensures the boards have adequate moisture resistance and durability and will have a life equal to that of the building.

Selecting a building board with good external performance and durability is important, particularly through the build phase, as the product may be left exposed for several months prior to a secondary facade being installed and enclosing the sheathing board.

Testing and certification to BS EN 12467:2012 also offers confidence of the building board’s durability requirement and that it can withstand the exposure cycle of freeze and thaw, heat and rain.

Behaviour in relation to fire

The building regulations for England and Wales set out the legal obligations for building designers. These functional requirements outline what must be done, but do not address how to achieve this. An example of a functional requirement that covers structural stability in a fire is that ‘the building shall be designed and constructed so that, in the event of a fire, its stability will be maintained for a reasonable period.’

Companies with recognised certified products generally make technical information readily available and the material safety data sheet for building boards and external cladding systems is a good starting point.

Fire Rating A1 and A2 refers to reaction-to-fire classifications for contribution to fire growth in accordance with BS EN 13501-1. A1 utilises BS EN ISO 1182 and BS EN ISO 1716 tests and is typically non-combustible rating referenced as ‘non- combustible’. A2 utilises BS EN ISO 1716 andBS EN 13823 testing and is referenced to typically as ‘limited combustible.’

CE marking

CE marking is a manufacturer’s declaration that the product meets the requirements of the applicable EC directives in terms of safety, health and environmental requirements. CE marked buildings boards appear under the harmonised standard of BS EN 12467:2012. Demonstrating that the manufacturer has checked that these products meet EU safety, health and environmental requirements is a key indicator of a products compliance with EU legislations and allows the free movement of products within the European market.

And finally…

Develop a relationship with your supplier – they can become a trusted information source and advisor when considering a particular system or experiencing a challenging issue. Some suppliers have a wealth of knowledge and no online technical specification tool can replace first-hand experience. Many will make their expertise readily available with free training and CPD seminars. It is also a clear advantage to be involved with a company that can offer full support in providing the complete through wall solution. Building a relationship with a recognised and credible supplier will mean that specifiers will have a valuable information source ‘at hand’ and be kept up to date with the latest developments in building board technology.