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Off the wall

30 Jul 14 With 90mm of foam insulation on the outside of your house, you'll be nice and warm. But where will you hang your satellite dish? David Taylor finds out

Calista's stainless steel bracket
Calista's stainless steel bracket

External insulation is a method of home-improvement whose time has truly come. It is often the only way to bring old, solid-wall homes up to current standards of energy conservation and in the social housing sector it has been a godsend.

In a nutshell, this technique involves wrapping an existing building in a nice warm jacket of expanded polystyrene or phenolic foam, usually finished off with a thin coat of cementitious render.

It’s a relatively quick fix and is popular with registered social landlords because it can be done with the tenants still in residence. But the technique is not without its challenges, the principal one being that the insulation material itself is soft, fragile and has no real strength. There is nothing solid to which you can attach external fittings such as satellite dishes, washing lines, drainpipe brackets and outside lighting.

The solution hitherto has been simple to the point of banality: nail or screw a big chunk of wood the same thickness as the insulation layer to the wall and then insulate around it. You then have something you can screw into that is fixed back to the building structure. In a career spent providing energy-saving solutions to the social housing sector, Paul Brown has always felt there must be a more elegant solution to this problem.

“I wasn’t comfortable with timber being used in this way,” says Brown. “If you’re a cladding supplier getting funding under the Green Deal or ECO-Funding, you have to give a 25-year insurance-backed guarantee,” he points out.

“How can you give this guarantee when your system is penetrated in various places by blocks of wood?”

Brown says that, on a typical house with an external wall area of around 40m2, up to 3m2 can be covered with these wooden blocks, creating cold bridges through the insulation, allowing damp to penetrate and creating a risk of decay. It simply isn’t a smart idea to embed pieces of wood in your insulation layer, he says. Brown’s background is in social housing – he was area director of the Connaught group up until its highly publicised demise in 2010. More recently, Brown spent almost two years as managing director of SERS (South West) and SERS Renewables (Wales).

He is now managing director of Calista, a business he set up late last year to provide a wide range of energy-saving and microgeneration services to the building industry. Calista, based in Tiverton, Devon, comprises a number of specialist divisions: Calista Insulation; Calista Renewables and Calista Consulting. It also has an offshoot called Retrofit Satellites, which is dedicated to promoting Brown’s solution to the challenge of fixing things to external insulation.

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Like all the best ideas, Brown’s solution is a simple one. Instead of nailing a piece of wood to the substrate, Calista makes a stainless steel bracket that can be screwed to the wall before over-cladding with insulation so that the steel arm protrudes from the finished surface. Only a small area of the insulation is penetrated and the stainless steel component won’t rot or allow damp to penetrate to the substrate.

Better still, the company has also developed a fixing method which makes it possible to retrofit a bracket or any other fixing through the finished insulation without damaging the surface render or gouging chunks out of the insulating foam.

“When we started looking for a better method, we wanted something that not only performed better but was commercially attractive too,” says Brown. His ranges of brackets and fixings offer that commercial incentive, he believes. They are quick to install and boast 60% lower labour costs making them 30 – 40% cheaper to install overall.

Brown says he had expected to attract the attention of contractors like SERS, but so far the company has had its best response from manufacturers. Cladding and insulation specialist Alsecco Façades already offers the Calista system as standard; and Brown says he is in the final stages of agreeing wholesale deals with top insulation manufacturers including Knauf, Alumasc  and Rockwool.

Calista offers a 60-year warranty on its stainless steel bracket system – which should see them outlive most external insulation systems. The company is now developing a range made from high-tensile injectionmoulded plastics and even these will carry a 25-year warranty.

“The margins are much greater with the plastic version,” comments Brown. Sales of the bracket have so far been small-scale, says Brown, but he expects to see them pick up substantially once he has finalised the wholesale agreements.

 [This article first appeared in the June 2014 issue of The Construction Index magazine, which can be viewed in full at:]

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