20 March 2008 14:36pm

Cladding Considerations

Fire Safety, Non-combustible core, Recycling, Sustainability, europanel, global warming, residential

Steel faced composite panels haven’t traditionally been a building system utilised by housing associations. However, modern day demands have seen a marked increase in the number of housing providers now turning to this method of construction. Richard Wigley, Marketing Manager for Eurobond Laminates, looks at the reasons why mineral wool cored cladding systems are particularly suited to social housing schemes.

Pressures to deliver attractive, energy efficient and quick-to-erect buildings have meant that designers are increasingly specifying a metal structure clad with composite wall panels.

Composite, or sandwich, panels comprise two metal faces positioned on either side of a thermally-insulating core material. The core is firmly bonded to both faces so that the three components act compositely when under load.

Many different core materials may be used in sandwich panels. Board materials, such as high-density structural stone wool, are adhered to the facings, while some core materials are injected between the facings so that they expand to fill the void and automatically adhere. Polyurethane (PUR) and the similar polyisocyanurate (PIR) are examples of these rigid foam cored composite panel products.

Composite panels do vary in terms of structural, fire, acoustic and thermal performance. When it comes to residential blocks, stone wool cored products offer the best solution, due to their superior performance on a number of levels.

Housing associations are frequently ‘up against it’ when it comes to delivering new accommodation and this is often the key reason why many turn to composite cladding systems. In terms of speed of construction, they compare extremely favourably against traditional brick and block, with stone wool cored cladding systems offering a number of additional benefits. In utilising a high density core it’s possible to achieve much longer spans, thereby reducing the need for secondary steelwork and so decreasing construction time still further. The longer spans afforded by stone wool cored cladding products also lead to a cleaner, uncluttered internal appearance and increase the useable internal area of a building.

Fire is another pertinent consideration when specifying any building system and for composite panels any potential risk is due to the reaction of the core material if it is ever exposed.

In the event of a fire the steel face of any composite panel will eventually expand and bow, causing the composite panel joints to open. With this in mind, Eurobond has always championed a stone wool core, as opposed to blown plastic foam, as even if the joints open up, the non-combustible core material won’t burn and it won’t contribute to fire spread or emit smoke.

If a blown plastic foam core, such as PIR, is the preferred option then in order to comply with the basic requirement for the most recognised industry standard, LPS 1181, specifiers must ensure the system is built in accordance with the actual tested construction. This means that plastic foam cored panels typically require the use of strip flashings, intumescent seals and physical stitching of the internal joints. However, it’s important to note that this does not give equal fire resistance to external fire attack, a significant point for housing associations, where the risk of arson is real.

Many housing associations also now operate within the parameters of an environmental procurement policy and as such are keen to only specify building products that cause minimal environmental impact.

Recycling and reuse of building materials is especially high on the construction industry’s agenda. In fact, some recent research by Eurobond found that architects predicted waste reduction and ease of building material re-use will become the most important environmental considerations going forward.

Those composite panels manufactured from stone wool are the only type that can be fully recycled. For instance, Eurobond’s Europanel, has already undergone successful trials demonstrating that both the composite panel steel and mineral wool core can be effectively re-cycled as part of a closed loop recycling process.

Studies have also calculated the Life Cycle Global Warming Potential of stone wool cored panels and demonstrated that from ‘cradle to cradle’ the system has a carbon footprint significantly lower than that of equivalent cladding systems, such as those with a polyisocyanurate [PIR] core. Figures are based on calculating carbon emissions from manufacture, transport, site construction, maintenance and end of life solutions.

The late adoption of composite cladding systems by housing associations could be down to aesthetics, with many finding it difficult to align their appearance to residential properties. However, the capabilities of some manufacturers have put paid to that myth. Significantly, Eurobond can demonstrate the ability to offer consistent, high quality architectural flatness, with secret-fix joints that create beautifully clean, uninterrupted facades, well suited to buildings where aesthetic appeal is important.

Some suppliers also offer a broad range of module sizes, providing far greater design scope. Europanel, for example, is available in module sizes from 300mm – 1200mm in 5mm increments, enabling feature bands to be provided in relatively small quantities, mixing colours to create really eye-catching exteriors, plus easy alignment of the composite panel joints with window heads and cills.

The company is also launching a Rainscreen Support Panel, therefore combining the speed of construction and performance benefits of stone wool cored composite panels with the ability to achieve even wider ranging aesthetics, from terracotta through to ceramic tiles, natural stone and facing brick.

A successful build project is one that can balance design flexibility, aesthetics, fire safety, construction time and the environmental impact of its building materials. Certainly in terms of composite cladding systems, those manufactured using a stone wool core, such as Europanel™, tick all the right boxes.