INSULATION AND PROTECTION: advances that will improve your buildings.
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Beat the bomb

Blast-enhanced curtain walling offers explosion protection
Curtain walling from Kawneer has been installed at Liverpool John Lennon Airport to protect the terminal building and people in it from a bomb explosion outside. The £1.8m glass facade runs the length of the north elevation of the airport terminal. Kawneer tested its system at an air force base in Cumbria. However, as major projects operations director Terry Whitham says: “It can’t be complete protection, but it can cope with 80% of the likelihood of a blast.” Kawneer is now fitting the system in other potential targets such as army barracks. The anti-blast features add around 30mm to the depth of the typical curtain wall. A 6mm layer of toughened glass on the outside of the building is separated by a 12-18mm cavity from a 10.5mm layer of laminated glass. The toughened glass helps the system withstand a blast, while the laminated glass will remain in place after impact and won’t shatter. Although the curtain wall may be defaced by an explosion, it will shield people in the terminal and its main infrastructure, saving the cost of refurbishment as well as lives. Site extension
Main contractor Bovis Lend Lease refurbished the main airport terminal building to handle three million passengers a year, trebling existing capacity. The curtain wall was built by SIAC Construction to integrate the refurbished terminal and the extension. “More and more, architects are losing the responsibility for design,” says Peter Cochlin, divisional director at SIAC. “The design of the facade was up to us – the weathering features and the blastproofing.” SIAC recommended Kawneer because data from the Cumbrian tests proved the system could withstand the specified force. Enquiry number 201

Another clip in the wall?

A fast-track brick system that lets you clip’n’Clad
Building brick walls is expensive and time-consuming. No surprise, then, that plenty of companies have come up with the wheeze of brick cladding systems. But the adhesive fixing of brick slips has a poor reputation in the construction industry, something that dates from the 1970s, when they acquired a reputation for falling off multi-storey buildings. To create a walling system that the industry would perceive as stronger, Baggeridge Bricks set up a subsidiary, Corium, to nurture a fast-track brick cladding system. The eponymous system is clay cladding, rather than insulation with brick slips stuck on. CLIP-A-Brick
Unlike stick-a-brick systems, Corium involves clipping brick tiles onto plastic-coated profiled steel rails fixed to a building’s substrate, where they are held firmly in place. The purpose-made tiles have a minimum design life of 60 years. Dispensing entirely with bricklayers (as well as the waste created by cutting the faces off bricks and junking the rest), Corium tiles can be installed up to three times faster than bricks can be laid on site. The support rails and tiles can be installed in any weather; only the pump-applied pointing is weather-dependent. So no more glowering at bolshy brickies waiting for a downpour to end. “The fastest bricklayer in Britain might be able to lay 1,000 bricks a day building a straightforward wall,” says says Phil Noble, technical and commercial manager of Corium. “In that time, one operative could put up the railing and 3,000 Corium brick equivalents.” ON TEST
Social housebuilder Laing Partnership has tested Corium at Seabright Street in London for Victoria Park Housing Association. The company used Corium, along with two other innovative cladding materials (through-coloured render and untreated hardwood), on the three-house terrace as an intergral part of its prime initiative to evaluate innovation before rolling it out. “Planners have very fixed ideas - like ‘all buildings should be made of brick and have chimneys’ - so we investigated various brick-type finishes,” says Laing development director Peter Marten. The problem, particularly at the ground floor level, was the durability of brick slips, which are vulnerable to impact but bonded to polystyrene, which makes repair difficult. With Corium, on the other hand, a damaged tile can be easily cut out and replaced, making repair a practical proposition. Corium was just as interested as Laing in seeing how its product performed. The technical and sales directors even turned up on site to personally clip on some Corium. They wanted to see whether it performed as well as they hoped it would. So did it? “We were very impressed,” says Marten. “It’s a very effective cladding that met our requirements 100%. The tiles are robust and the mechanical fix is very strong. It’s very quick to put up. And it maximises the amount of floor space in a development, which is important if you’re tight on a site.” There were issues for Laing, though. Price was one, although that’s not unusual for a new product and should fall with volume production. The range of patterns and textures was also too restricted. If anything, Corium is too robust: at 38mm thick overall, it’s fairly heavy. FINISHING TRADE
The product is aimed at builders and contractors. It’s fast-track, which can save time on the programme, it’s lightweight, so you can use a cherrypicker rather than scaffolding and its thinness increases the usable floor area. “It takes brickwork off the critical path and turns it into a finishing trade,” says Noble. “You can split the process, fixing the rails first and coming back subsequently to clip on the bricks and pump-point, to gain early enclosure.” Corium is usually considered for vertical walling applications, although the firm grip of the rails allows it to be used for ceilings too. Nor do the support rails have to be placed horizontally on a wall - they could be placed at any angle. It comes in a range of colours, textures and sizes, and any bond pattern can be achieved without adversely affecting performance or build time. With several small-scale projects now under its belt, Corium is ready to move into large commercial projects. According to Noble, the system has been specified by a substantial number of schemes. The next phase of product development will be to manufacture larger tiles and rainscreen cladding. Enquiry number 202

Think zinc

The not-so-heavy metal is useless for cladding... ISN’t It?
AME Facades is best known for aluminium and steel modular cladding, but a couple of years ago the company began investigating zinc panels. Aluminium cladding is popular but a turn-off for the designer seeking the natural look. Aluminium doesn’t weather well and needs a protective coating to be of any use for external work, so it just doesn’t hack it as a natural material. Zinc has that natural look, and is just about the most flexible metal you can get, which is why it is so useless as cladding. Unless it was made extremely thick, a length of zinc on the side of a building would simply flap around. And stopping a thin sheet from undulating would require just too many fixings. Accordingly, AME decided to bond thin (1.5mm) zinc panels to 25mm thick aluminium honeycomb with an aluminium backing sheet as a balance to give the panels the strength and flatness needed. The biggest technical problem was working out how to bond the zinc to the aluminium without getting a bi-metallic reaction. Coating counts
The solution was to apply a coating to stop the metals coming into physical contact. And designing a 15mm recess between each panel gave the zinc room to expand freely. AME designed the 2000mm by 900mm Zinc Proteus HR panels to fit the width of the ten tonnes of zinc coil required for its first zinc cladding job on the Ebor Stand at York Racecourse. Some 850m2 of AME’s zinc rainscreen is stacked on site ready to be installed at the York grandstand this winter. Because simply touching the metal will mark it with fingerprints, the zinc leaves the factory covered with a protective film. “It’s touch-sensitive, so it has to be handled with kid gloves,” says Mark Fellows of the cladding installer Speedwell. “But putting it up presents no problems.” Enquiry number 203

Men and machine

All too easi as JLG take on the biggest cladding job in UK
JLG Industries’ Easi-Cladder machine is making its presence felt on the biggest cladding job in the UK, a new Argos distribution centre in Marsh Leys, Bedford. Developed by manufacturer JLG, the Easi-Cladder mechanically lifts, holds and positions cladding panels weighing up to 100kg, saving cladders the strain of heavy lifting, and speeding up the process. BEATING FATIGUE
The huge Argos building needed lots of panels, averaging 1m by 6.25m. The gangs using the new device have not only been faster, but required fewer men and suffered less fatigue than those using the traditional method of manual handling. “Productivity increases noticeably because the Easi-Cladder gets round the fatigue factor,” says Steve Smith, project manager for contractor Keyclad. Manufacturers have responded to the beefing up of thermal insulation requirements by increasing the core depth of their cladding panels. Larger panels also reduce number of air leakage points in a wall. “Cladding panels already typically weigh anything between 60kg and 80kg,” says Andrew Fishburn, European marketing director at JLG. “The bigger, heavier panels the industry is moving towards will be even harder to handle without mechanised assistance.” GM Services in Manchester has been testing Easi-Cladder in the field. In their trials, using a single Easi-Cladder allowed a team of three to put up 30% more cladding per day. “The cladders earned the same per-square-foot pay in a much quicker time,” says GM’s contracts manager, Mark Colbert. JLG’s Fishburn claims the Easi-Cladder can also make economic sense. “A 30% productivity increase could cut a 10-week job to seven weeks, so if you’re paying four cladding operatives £15 an hour and the cladding contractor £20 an hour, it would save you £6,000,’ he says. Enquiry number 204

Smoother operator

Fischer develops glass-fixed glazing anchor
The advanced curtain walling technique department at Fischer has developed a glazing anchor fixed within the glass itself. Anchored into an undercut hole within the body of the glass, the fixing does not penetrate all the way through to the other side of the glass. With no protrusions outside the glazing, the undercut glass anchor gives a totally flush facade. GLASS HOUSES
Century House in London’s Westminster Bridge Road is the first time the fixing has been used in the UK. LMC company Metal UK used the system, called Sheerglaze FZP-G, to install the building’s entrance screen elevation and adjacent link bridge curtain walling. Metal UK’s sister company Glass UK used a machine licensed from Fischer to pre-drill off-site the eight undercut holes in Century House’s 74 green glass panels. The panels, which are just 10mm thick but measure 2.8m by 1.8m, were drilled in their annealed state and sent for toughening and heat treatment before being returned to the factory for installation of fixings. Because everything is quality assured and all preparation is done in the factory, the installation is a mechanical process. A glazier simply has to connect the glass panels to the brackets and fix them. CLEAR BENEFITS
The absence of external fixings makes cleaning the clear glass panels easier and prevents streaking caused by dirt trapped in external fittings. Maintenance is also cheaper because expansion stress and the entry of damp and dirt along the fixing are eliminated. The undercut anchor also reduces thermal bridge. Enquiry number 205

Testing times

TEST CENTRE answers the biggest question: WIll it work?
In construction, failure is never far away. But there is a way to make sure it doesn’t happen on site, and that’s by testing it. At Taylor Woodrow’s cladding and curtain wall testing centre, which moved last year to Leighton Buzzard, the failure rate for a first attempt at passing a battery of tests on system characteristics is around 25% - a vast improvement on the 90% rate of 15 years ago. FAILURE RATES
The high rate of failure comes from the bespoke nature of many of the systems tested, which are often one-offs for a particular project. As well as allowing manufacturers to design out any faults before it gets serious on site, testing systems at the UK Accreditation Service centre helps installers learn how to erect them effectively. The centre makes the learning curve plain, with installers coming back to sort out problems. Workmanship is the biggest problem uncovered by testing, typically because the cladding design is new and the erectors haven’t installed it before. “Training is a significant factor in failure. It’s important to control workmanship,” says Ray Elliott, principal consultant at Taylor Woodrow, which as a constructor has itself recently moved away from appointing cladding contractors on a tender basis to operating a select and much smaller approved installer list. Many of the UK’s most prestigious construction projects are tested at the centre, whose procession of false frontages give it the air of a Hollywood lot. The centre prepares a test chamber for a particular cladding type and the supplier’s installers then seal the open side of the chamber with the cladding sample. One of the biggest problems for cladding is the area where a curtain wall meets concrete – so the test rig incorporates those interfaces. The chamber is then depressurised to mimic the external forces on cladding and tests are run for water and air infiltration and wind resistance. Running the three tests costs £12,000 and avoids the potentially disastrous con-sequences of failure on site. There is also an impact test, where a ball bearing the size of a shot-putt and a canvas bag filled with 50kg of glass beads are swung at the cladding. Under pressure?
Taylor Woodrow also has a water test where a Shackleton 2,500hp aircraft engine blows back water onto the cladding, the chamber being repeatedly depressurised and repressurised to mimic the buffeting of storms. The company has also created a test that combines chamber pressure differential with a movable water fan. Enquiry number 206

Supplier news

  • Lead times for manufacturing curtain walling have fallen by three weeks, according to Mace’s regular survey. The main reason for the reduction, says Mace, is that many big London projects are now coming to an end.
  • Worcester-based metal cladding manufacturer Ridal is withdrawing its insulated composite panel products. The company says it will focus on standing seam and profiled cladding, as it has been unable to offer consistent quality on composite products and there are questions over the future of insulated composite panels.
  • Building systems and software applications group Eleco has bought Downer Cladding Systems. Downer supplies proprietary and bought-in support and fixing systems for rainscreen facade cladding as well as technical support services.
  • BRE and industry partners have produced a free, DTI-funded leaflet advising building owners and occupiers on their legal liability and damage limitation for building facades. It advises on condition surveys, planned inspection and maintenance, component durability, inspection frequency and whole life performance. Download the guide from the BRE website at www.bre.co.uk/press.
  • Kingspan has published a guide on the new Part L of the Building Regs, called Approved Construction Details. It looks at the practical implications of the regulations and focuses on the construction detailing needed for compliance.