We asked four leading facade, cladding and envelope specialists what they would tell architects and specifiers if they had the chance. This is what they told us. Michael Willoughby reports.
Chris Macey, group MD, Wintech Group
When windows and facades were first made by craftsmen, they were hand built products. The quality of materials used to create weatherproof integrity was not great. They were usually natural materials like timber or stone.
So if they wanted to make something waterproof they had to do it on the basis of shape rather than performance- specific materials. Tiled roofs are a good example. There are no sealants in a tiled roof.
We seem to have lost that now in facade engineering, becoming more reliant on sealants and gaskets to keep the weather out. Modern materials, technologies and designs become more reliant on performance materials.
These depend on: the quality of the workmanship, the way in which they are installed, the quality with which they are installed, the environment in which they are installed, the quality of the material and its application. With all these variables, there is plenty of opportunity for something to go wrong. It’s important to have designs which have a degree of redundancy on the basis of shape rather than materials so that you are not reliant on one component’s performance.
For example, we know that thresholds on doors have to be a certain height to keep the weather out. More and more we are seeing designs that rely on compression gaskets. If these fail for one of the reasons mentioned before there will be a problem. On the other hand, pressure-drained and equalised systems apply the redundancy principle. If the gaskets on the products fail and don’t work properly, the system itself is drained and ventilated.
Secondly, increasing emphasis on energy conservation means that we have to change the way we design buildings. Traditionally, the architect gets the service and structural engineers to tell him what he needs in terms of environmental and structural performance to create his building. Then at some point in the future, those details find their way into a performance specification for the building envelope.
But we are finding there is a gap in performance terms between the requirements for the required levels of energy conservation that services engineers have to meet to achieve statutory compliance and what can actually be designed and delivered.
Architects have to think of constraints that energy conservation has on their design freedom. This has started to restrict the amount of transparent area you can have on residential buildings. Windows have a lower thermal insulation performance but a service engineer needs to meet a certain U-value.
There is an urgent need for facade engineers to be involved earlier in the design and development of projects so that these things don’t become a problem at the point you have planning permission.
We’ve had projects where the levels of performance are so depressed and certain features of the architecture have meant those performances requirements can’t be achieved.
So far, it’s usually possible to massage the design to prevent a planning problem but I can see shortly – especially when the new ventilation requirements start to bite – that we will be getting planning permission for buildings that can’t be built at all.
Chris Horsfall, group business development director, Lakesmere Building Envelope Specialists
An architect will always scour the market himself for suppliers. He will always look for something unique so he can put his stamp on the building. He gets in touch with the suppliers himself and calls them in. That supplier is likely to sell him what they think will win them the job. This might not be the best thing for the architect. Suppliers will give him what no one else can provide.
The problem is compounded when you have an architect who goes to multiple suppliers. So, on a facade he could end up talking to 10-20 suppliers. Each of these will give him limited support because they are only interested in selling their product. That means they don’t have to worry about how it’s going to be engineered or integrated into the other product. They will only give him the selling price and not the final cost.
The architect will end up with a jigsaw of products and expect them to work together. We get called in and we start giving advice. The architect then feels marginalised because we are telling the construction people the reality and the architect is backed into a corner. The process is fragmented.
There are a few risky items out there at the moment. Architects are using a lot of lightweight stone and glass-reinforced concrete products that look like stone but aren’t. There are inherent risks in these because you have to understand the supply-chain and the buildability.
There are good and bad suppliers out there. If you don’t get the right materials from the right quarries you get wrong batching or colour, or stone which is poor-quality, chipped, damaged and not fit for purpose.
If we do look at a new product, we put 6-12 months due diligence into it before we would even consider using it to make sure it’s right. How can someone that’s picked something out of a brochure expect it to be correct?
We find it best if an architect builds up a relationship with a facade specialist who is used to the industry and knows all the products and different combinations and how all the interfaces work. They can go and see the architect and give him advice about what all the products can do as well as advice about risks and practicalities and the true cost of the end result on the building, including design, installation, management, purchase and delivery – not just the supplier’s selling price.
Simon Armstrong, managing partner, Cladtech Associates
Architects need to take proper notice of their obligations under the Construction Design and Management (CDM) regulations (which have recently changed) and consider the long-term maintenance of the facades for which they are producing the conceptual design.
Some of the most famous architects in the world do not consider this fundamental requirement and the buildings are impossible to maintain or to maintain economically.
There are buildings with quite large pieces of glass in difficult-to-access locations where it can cost between £25-55,000 to replace one piece of glass. The problem with externally clad or glazed buildings is that you have to consider the dead-load of the glass as well as the people needed to replace the glass units. So the unit might cost £1,000 to procure but then it costs another £25,000 to incorporate it into the facade of the building.
If they consider it, they would use smaller pieces of glass unless there was a reasonable method of accessing and replacing larger pieces.
Laurence MacBeth, sales and commercial director, Alumet Systems
We try to create something that will be commercially viable – that will look nice, keep the water out, be thermally efficient and make us a profit. Meanwhile, an architect goes for the antithesis: he wants to build something that will be uniquely “him.” I try to make it look like the architect’s dream by following the quantity surveyor’s route! Usually we end up with a compromise that’s somewhere between the two.
So, I would ask architects to take a closer look at the products that are available as standard in the marketplace that we can mould into their architectural premise. A bit more thought about what’s available would mean they could get what they wanted by using standard subcontractors rather than having to reinvent the wheel.
If they spoke to suppliers individually, the architectural team would find a wealth of experience in what makes a building work that they might not think about. We can make it easier to build, cheaper, lighter and by using less material and achieving a lower carbon-footprint.
So, for example, we might be able to direct them towards other forms of insulation, not just the standard solution. There could be a thinner and better-performing foil-packed insulation with higher U-values which would be more expensive per square foot, but leading to thinner walls so you get more usable floor space.
More practicality wouldn’t go amiss, either. There is a general assumption that form is more important than function. They are still very good at the aesthetics of buildings but not so much at how it works.
People like Barclay Homes, who we’re doing a lot of work for at the moment, tend to get the specialists together and meet as a team to solve issues of design. You’d be surprised how long that takes. We are almost still designing things until the end of the job because the plan doesn’t work and things have to be redesigned.
A recent project we designed had a practical failure in that the enclosed balconies had been designed with almost no thought given to exactly how they were going to drain. It was never going to work. We, the envelope contractor, had to re-design it on the hoof, because the architects had given little thought to the function.