There’s a myriad of facade finishes which change and evolve with fashion. The sector has had to cope with reduced funding, but technological developments are breathing new life into this colourful exterior category, with new products, improved performance and longer life. Adrian JG Marsh reports.
“It does seem that designers are moving away from EWI render systems, towards rainscreen cladding,” said Kevin Naughton, managing director at Hatfield-based specialist contractor RPN, who’s seen more of a mix in the type of materials used in facade finishes. “We’ve seen this in the number of tenders we’ve received in recent years. This is due to the large range of aesthetic options with rainscreen cladding compared to render.”
Peter Baker, commercial director at Stanmore, the specialist drylining, facades, metal work and glazing contractor, has seen that the interpretation of building regulations when working above 18 metres has had an impact on the competitiveness of EWI against rainscreen as system designs change. He commented: “There are more fire breaks and more fixings which means there’s more to do, so traditional rates per metre don’t work anymore. There’s also been a trend away from EPS (expanded polystyrene insulation) to mineral wool (insulation) with greater use of rainscreen and glass.
“Render is less popular with designers [on high rise] who are using a mixture of finishes such as rainscreens and glass. Even a brickwork finish has become fashionable again, but using traditional brickwork at high level is generally not an option because of the loads and weight, so clients are looking for lightweight solutions such as brick slip wall panels.”
Greg Astell at Sto sees thermal transmission of the substructure being important and said: “We’ve found stainless steel brackets have a better performance for thermal transmission and they’re stronger. They’re not conducting as much heat as aluminium and often you do not require as much insulation, which reduces the thickness of insulation required.”
Innovation is driving productivity
The onus is definitely on manufacturers to innovate and help their customers to work smarter and so develop products that take into account the impact of climate change from both an installation and user point of view.
Saint-Gobain Weber has recently developed and introduced webermineral TF, a through-coloured render that can be applied in temperatures as low as 1°C, which is ideal for winter working and allows installers to keep going when they would normally be forced to postpone works. And as the UK climate does have a reputation for rainfall, the system has also been designed to be rain-resistant to prevent wash off in as little as one hour (at 20°C).
Another issue to contend with is that of algae growth, a global problem. Algae growth on external surfaces is not a new phenomenon but its increase is due to warmer winter climates and prolonged damp weather conditions. In conditions that do not fall below zero temperatures, algae spores continue to grow and can affect many exposed surfaces. Although algae does not affect the performance of render, it can sometimes become unsightly.
Tracey Dempster, head of marketing at Saint-Gobain Weber, said: “Over time, weathering and condensation build-up can erode the fabric of a building and ruin the appearance, meaning thermal insulation requirements fail to be met and the value of the property can seriously decline.”
Weber has worked closely with French microbiologists to understand the effect of the composition of render and also the effect that external factors have to play, such as dew point, surface condensation, temperature and rainfall.
Technology for system designers and manufacturers brings a blend of performance in terms of impact and crack resistance and water repellence. Gary Bundy from Sto explained: “You want high performance to please the specifier and owner but you also have to have something that is easy to use. We work hard at that to get material characteristics that are user friendly for applicators.
“We’re looking at biomimicry to emulate nature and the way plants shed water. If a facade sheds water easily it gets dry quicker and is less prone to getting dirty or allowing algae to grow.
“Different materials mean surfaces can react in different ways: they could be self-cleaning or quick drying, and some actually mimic a desert beetle! These new materials can help to double the life of a building.”
There is still a strong market for render, as the move into the UK by Baumit, an Austrian-based manufacturer, has shown. They offer a full range of traditional and synthetic materials.
Ben Warren, managing director at Baumit, said: “Fashions are changing and this goes along with the technology. Our main focus in the UK is EWI and render. Visual effects are quite phenomenal; for example, we can create a wood effect or a sculptured finish.”
One of Baumit’s first projects has been a private passivhaus scheme in Norfolk. FPP Facades installed Baumit’s ‘Open system’ which is a fully breathable EWI system finished with Baumit NanoporTop render finish and a lime render internally.
The materials that now feature on facade finishes are much more sophisticated: there is a mixture, ranging from render through to glass, terracotta and lightweight brick slip and there’s more. Facade finishes are a key component in bringing a building – new or refurbished, large or small – to life.