Stronger, swifter, safer: advances in ROOFING that will improve your buildings.
A glass act
RAPID-FIX ROOFING means an express solution for waterloo stationSOMETIMES YOU HAVE TO GLUE, And dow’s adhesive has stickability
Is it better to glue or to screw? It’s no surprise to hear Dow Chemicals lavishing praise on its Insta-Stik polyurethane roofing adhesive as quick, easy to use, clean, quiet and safe – but we’ve found a user smitten by its charms. Let’s take them one by one. First, speed. “It’s about four times faster than mechanical fixing,” says Tony Burgoyne, flat roof manager at Allmass Cladding. Allmass has helped convert a Maples furniture warehouse to the Pavilion leisure, retail and housing complex in Bristol. He reckons on driving in four or five screws to secure each square metre of roof covering, and the Pavilion programme was just too tight to allow that – the only way Allmass could install the 1,500m2 of roofing in time was to glue it down. Burgoyne also rates Insta-Stik as up to two times as fast as other adhesives. It comes out of its dispenser as ready-expanded polyurethane, so there’s no waiting around for it to foam up. It’s also quicker than bitumen fixing, as contractors have to wait for bitumen to be heated before use. As for ease of use, Insta-Stik comes in a portable, disposable container attached to a dispensing wand with a flexible hose; for large jobs, you can lay it down in multiple beads from a trolley-mounted container. It’s a simpler operation than rolling it out or punching holes in a can and shaking it about. Insta-Stik also puts down a thick bead of glue, which makes application easier, as the installer can see there’s enough to stick the material down properly. “It’s got more body than other poly-urethanes, so it grabs and sticks better,” says Burgoyne. And because it comes out in pre-foamed form, you get better control in applying it. What about clean and quiet, then? Fastening roofing materials by screwing or bolting creates a lot of vibration, and leads to dust and debris falling from ceilings. Insta-Stik eliminates this problem and complaints from occupants in a refurb job. At the Pavilion, Burgoyne glued down a felt vapour barrier as a temporary seal until the weatherproof membrane went on – screwing the felt down would have let rain in through the fixings. So that just leaves safe. Cold-applied Insta-Stik is safer than hot bitumen, which exposes workers and the building to the risk of splashback, burns and pot fires. The safer working environment should also mean lower insurance costs for roofing contractors.
Enquiry number 202
Graham Donaldson’s a hard nut to crack. He manages an estate of pieds-a-terre for the seriously rich, but was sceptical of an otherwise attractive roofing tender from Liquid Plastics Limited (LPL). “As a surveyor myself, I was very concerned that LPL was just adding a coat of paint to a failing system,” says the factor of Guthrie Court at Gleneagles in Scotland. Robert Grey, specification development manager in Scotland for LPL, set out to convince the refurbishment committee, which is stuffed with architects and building professionals. “Everyone thinks a leak means stripping off the whole roof,” says Grey, “but they’re wrong.” To back up his argument that the three-layer felt roof was essentially in good condition, Grey took core samples and then produced his trump card: an infrared night-time scan of the roof. The £10,000 scan identified which insulating panels were wet – and they amounted to only 5% of the 2,000m2 roof covering. Donaldson peeled back the felt to check the scan’s accuracy, and came back down convinced. Grey replaced the insulation in the areas where the scan showed it had failed before covering it with Decothane Delta 25. The cold-applied polyurethane coating with glass fibre matting reinforcement is not a patch repair. It completely covers the roof and is guaranteed for 25 years before the first maintenance. Although LPL was slightly cheaper than its rivals, price wasn’t the biggest benefit for Donaldson. Using the coating sealed the roof and left it watertight. And it would have taken much longer if the entire roofing had been stripped off and replaced. “With LPL, it was more like a painting job,” says Donaldson.
Enquiry number 203New solar panels a doddle to install
Traditionally, you build the roof, then bolt on the solar panels. But now, instead of putting solar panels on as an afterthought, you can use them to build the roof itself. At the Beddington Zero Energy Development near Croydon, architect Bill Dunster used panels from BP Solar for vertical glazing and sloping rooflights as well as mounting them, old-style, above the roof. They look impossibly high-tech and futuristic, but building with them is a piece of cake. “I wish I could say it took amazing ingenuity on our part to install them,” says GTCM’s Eric Muscat, the construction manager at BedZed, “but it didn’t.” All it needed, he says, was careful handling. The cost of the panels makes breakages expensive and puts them high on the nickability list, so he stored them in secure compounds and made sure the contractors handled them with respect. The result? Not a single panel was stolen or broken on site. Muscat also made sure the contractors kept the panels covered up until they were in place, because they start generating electricity and become live as soon as the sun shines on them. The panels sandwich a layer of photovoltaic silicon cells between two layers of glass. While light can’t pass through the cells, it does go through the space between them. So the panels let daylight in but, because you can specify the amount of clear space between the cells, also provide as much or as little shade as your building needs. The panels are decorative and can be used as glass in curtain walling as well as roof glazing. Two wires project from each panel, linking it to the one before and the one after it. The first and last wire in a series connect to a standard inverter that converts the DC electricity generated by the cells to AC and channels it back into the building’s mains electricity or a grid system. According to BP Solar, the typical British home could supply all its energy needs by installing panels on the south/south-west facing half of its roof area. Although the solar market currently supplies only a tiny fraction of energy demand, the government wants it to generate 50% by the middle of the century. To create that market, it is subsidising construction clients who install solar panels, providing 40% of costs for commercial projects, 50% for housing and 65% for all public buildings.
Enquiry number 204
Your client wants to build a distribution centre on a greenfield site. Problem is, it’s on a floodplain and the local planning department is determined not to add to flooding problems in the area. As a result, it won’t grant permission unless you can prove the rain run-off will be no greater than the fields the centre is built on. Your best hope could be to go green, with the Kalzip Nature Roof - a roof covered with hardy plants that will store rain. A Nature Roof holds around 60% of rainfall on the roof, allowing it to evaporate. Building a green roof is not particularly difficult. The Nature Roof fits on top of Kalzip’s well-established standing seam roof system, and will work at up to 30 degrees of pitch. The standing seam roof is the usual layer of insulation topped with aluminium sheets whose upright edges are clamped together for a completely watertight surface uncompromised by any holes or screws. The trick is the rainwater reservoir mat, which is made up of hundreds of small cups arranged like a large egg tray. When the cups are full, rainwater spills over and drains away through the eaves and guttering. A planting substrate covers the mat. This is a layer of fire-blown clay that looks and feels like cinders. At 75kg per square saturated metre, it’s a third as light as simple grass or turf roofs. The roof is planted with a mixture of young sedum plug plants, low-growing perennials that live in rocky soils and can tolerate extreme conditions. The filter web stops plant debris clogging up the gutters. Instead, dead flowerheads and leaves blow away. There’s no need for watering and maintenance involves a visit once a year by Kalzip to apply a liquid plant feed and spray any diseased areas. Obviously, it’s more expensive to install a Nature Roof than just a standing seam system – it will double the cost – although installation is fast and simple. But with extreme conditions bringing more stringent planning controls over drainage, a green roof may be the only way to get your project built.
Enquiry number 206FAST LANE CHECKOUT FOR TESCO’s ONE-PIECE ROOF
Taylor Woodrow’s installation of 10,000m2 of TopDek single-piece roofing panel earlier this year on a new Tesco supermarket in Doncaster gave a watertight roof in three weeks – just over half the time it would have taken with a traditional, layered construction. TopDek, from Ward Building Components, is a one-piece roof panel that combines a 1.2mm single-ply PVC outer membrane with a firesafe-protected core and a steel deck. The panels are fixed to Ward’s Multibeam purlin sections. Dick Janney, Taylor Woodrow customer service director, reckons that the installed cost of TopDek and built-up roofs are similar, at around £27 per square metre. But he rates speed as one of TopDek’s prime benefits. “It only has to be screwed down once,” he says. While faster materials will always attract a construction manager’s attention, TopDek also has safety benefits. Installation is a one-pass operation, so it creates an instantly safe roof. The weather poses fewer problems for laying TopDek as there’s no liner to be blown away in high winds. “Hail, rain, snow – it really makes no difference at all,” says Eddie Hilditch, contracts manager at Cobsen Davies Roofing, who has installed TopDek on two Tescos so far. Taylor Woodrow ran acoustic tests on the panel, fearing the single-piece build would act as a drum in the rain. It didn’t. It was airtight too. An air leakage test gave the Doncaster store a rating of 1.56m3/hr/m2 compared with the maximum leakage of 10m3/hr/m2 laid down by the Building Regulations.
Enquiry number 205The CIOB-led Hallmarked roof scheme has encountered a last-minute hitch. While manufacturers and contractors have already been accredited, roof designers are dragging their feet. A roof cannot be classed as Hallmarked unless all three parties to it are accredited. HSE blitzes have persuaded many manufacturers to make their roofs less fragile. Eternit, for example, has been putting polypropylene strips into its fibre cement sheeting so workers can’t fall through. Weight is predicted to be the next area of change, with the arrival of easy-handle sheets. The Flat Roofing Alliance has warned that many small roofing firms cannot afford the rocketing premiums for liability insurance and will be forced out of business, bringing sites to a stop. Having outgrown the facilities at its Belgian plant, Liquid Plastics has turned the factory into a distribution centre. LPL now ships products from its UK plant to the centre, which supplies Europe and has seen sales grow by 20% this year. Brownfield regeneration is boosting the prospects of natural slate as planning issues and environmental requirements lead planners to specify natural materials. Architectural Glazing Solutions has produced a guide to unexplained glass failure in overhead glazing, detailing the failures suffered by different glass types and providing solutions with laminated architectural glass. Telephone 020 7535 5678.
RAPID-FIX ROOFING means an express solution for waterloo station
Replacing the roof that covers 19 of the platforms at Waterloo Station is a huge undertaking. Not just because it covers the equivalent of five football pitches, but because it had to be replaced without interfering with the running of one of London's busiest train stations. Construction Manager went along to see the rapid-fix roof system at the heart of the project and also encountered a unique new rig (see 'Let's roll', below).
The old wooden-frame trainshed roof was past it. Although the steelwork was in good shape, Railtrack had been repairing the roof for years, and ended up with a patchwork construction of glass, plastic and timber. It all had to go.
But cranes couldn't span the area, so new materials would have had to be passed onto and off the site. And scaffolding would have had to go down to platform level to take the load.
The solution was to hang a protection deck from the roof trusses, which offered a working platform for contractors immediately under the roof and high above the day-to-day work of the station. "We're hanging right off the roof structure," says Tony Ingram, roofing construction manager for Amec. "People don't know we're here."
With access sorted, Amec moved on to what type of roofing to put up. The roof was built in situ 100 years ago. Although the roof's nine barrels look the same, each has a different shape and length, so a flexible system was essential. "Five millimetres here and there on a panel system would cause major problems," says Amec project manager Roy Conway.
Instead, the contract went to Lonsdale Metal's Skygard roof framing system. Each component can be lifted and moved by one man, and its simple design makes it ideal for a repetitive job. "You can't get anything quicker and more basic," says one of the installation team.
Lonsdale had to make changes to Skygard to fit the project spec. To ventilate the station, the new roof had to have large air gaps where the three tiers of glazing overlapped. Rather than create a bespoke product, Lonsdale redesigned the fixing bracket as a box section, lifting the glazing bars to give a 150mm airgap rather than the standard 18mm.
Now roofing contractor Kelsey is delivering on the fast-track promise, glazing around 600m2 a week. Project manager Steve Arthurs says that metre for metre, the company is completing the job in two-thirds of the time it took it to reroof Glasgow Central.
Enquiry number 201
Let’s roll
The brainchild of a contractor’s consortium, the rolling rig looks like a ziggurat on legs. It is a set of ascending work platforms stacked on top of a giant table with lockable wheels that run along steel rails on the protection deck. Because the platforms fold down onto the table, roofers can push the rig under the curved roof trusses from one roof bay to the next without having to dismantle it each time.Stop screwing around
Is it better to glue or to screw? It’s no surprise to hear Dow Chemicals lavishing praise on its Insta-Stik polyurethane roofing adhesive as quick, easy to use, clean, quiet and safe – but we’ve found a user smitten by its charms. Let’s take them one by one. First, speed. “It’s about four times faster than mechanical fixing,” says Tony Burgoyne, flat roof manager at Allmass Cladding. Allmass has helped convert a Maples furniture warehouse to the Pavilion leisure, retail and housing complex in Bristol. He reckons on driving in four or five screws to secure each square metre of roof covering, and the Pavilion programme was just too tight to allow that – the only way Allmass could install the 1,500m2 of roofing in time was to glue it down. Burgoyne also rates Insta-Stik as up to two times as fast as other adhesives. It comes out of its dispenser as ready-expanded polyurethane, so there’s no waiting around for it to foam up. It’s also quicker than bitumen fixing, as contractors have to wait for bitumen to be heated before use. As for ease of use, Insta-Stik comes in a portable, disposable container attached to a dispensing wand with a flexible hose; for large jobs, you can lay it down in multiple beads from a trolley-mounted container. It’s a simpler operation than rolling it out or punching holes in a can and shaking it about. Insta-Stik also puts down a thick bead of glue, which makes application easier, as the installer can see there’s enough to stick the material down properly. “It’s got more body than other poly-urethanes, so it grabs and sticks better,” says Burgoyne. And because it comes out in pre-foamed form, you get better control in applying it. What about clean and quiet, then? Fastening roofing materials by screwing or bolting creates a lot of vibration, and leads to dust and debris falling from ceilings. Insta-Stik eliminates this problem and complaints from occupants in a refurb job. At the Pavilion, Burgoyne glued down a felt vapour barrier as a temporary seal until the weatherproof membrane went on – screwing the felt down would have let rain in through the fixings. So that just leaves safe. Cold-applied Insta-Stik is safer than hot bitumen, which exposes workers and the building to the risk of splashback, burns and pot fires. The safer working environment should also mean lower insurance costs for roofing contractors.
Enquiry number 202
Death sentence repealed
A Simple scan saved the roofGraham Donaldson’s a hard nut to crack. He manages an estate of pieds-a-terre for the seriously rich, but was sceptical of an otherwise attractive roofing tender from Liquid Plastics Limited (LPL). “As a surveyor myself, I was very concerned that LPL was just adding a coat of paint to a failing system,” says the factor of Guthrie Court at Gleneagles in Scotland. Robert Grey, specification development manager in Scotland for LPL, set out to convince the refurbishment committee, which is stuffed with architects and building professionals. “Everyone thinks a leak means stripping off the whole roof,” says Grey, “but they’re wrong.” To back up his argument that the three-layer felt roof was essentially in good condition, Grey took core samples and then produced his trump card: an infrared night-time scan of the roof. The £10,000 scan identified which insulating panels were wet – and they amounted to only 5% of the 2,000m2 roof covering. Donaldson peeled back the felt to check the scan’s accuracy, and came back down convinced. Grey replaced the insulation in the areas where the scan showed it had failed before covering it with Decothane Delta 25. The cold-applied polyurethane coating with glass fibre matting reinforcement is not a patch repair. It completely covers the roof and is guaranteed for 25 years before the first maintenance. Although LPL was slightly cheaper than its rivals, price wasn’t the biggest benefit for Donaldson. Using the coating sealed the roof and left it watertight. And it would have taken much longer if the entire roofing had been stripped off and replaced. “With LPL, it was more like a painting job,” says Donaldson.
Enquiry number 203
The generation game
Traditionally, you build the roof, then bolt on the solar panels. But now, instead of putting solar panels on as an afterthought, you can use them to build the roof itself. At the Beddington Zero Energy Development near Croydon, architect Bill Dunster used panels from BP Solar for vertical glazing and sloping rooflights as well as mounting them, old-style, above the roof. They look impossibly high-tech and futuristic, but building with them is a piece of cake. “I wish I could say it took amazing ingenuity on our part to install them,” says GTCM’s Eric Muscat, the construction manager at BedZed, “but it didn’t.” All it needed, he says, was careful handling. The cost of the panels makes breakages expensive and puts them high on the nickability list, so he stored them in secure compounds and made sure the contractors handled them with respect. The result? Not a single panel was stolen or broken on site. Muscat also made sure the contractors kept the panels covered up until they were in place, because they start generating electricity and become live as soon as the sun shines on them. The panels sandwich a layer of photovoltaic silicon cells between two layers of glass. While light can’t pass through the cells, it does go through the space between them. So the panels let daylight in but, because you can specify the amount of clear space between the cells, also provide as much or as little shade as your building needs. The panels are decorative and can be used as glass in curtain walling as well as roof glazing. Two wires project from each panel, linking it to the one before and the one after it. The first and last wire in a series connect to a standard inverter that converts the DC electricity generated by the cells to AC and channels it back into the building’s mains electricity or a grid system. According to BP Solar, the typical British home could supply all its energy needs by installing panels on the south/south-west facing half of its roof area. Although the solar market currently supplies only a tiny fraction of energy demand, the government wants it to generate 50% by the middle of the century. To create that market, it is subsidising construction clients who install solar panels, providing 40% of costs for commercial projects, 50% for housing and 65% for all public buildings.
Enquiry number 204
Plant higher
KALZIP HAS A Natural SOLUTION TO YOUR WATER TORTUREYour client wants to build a distribution centre on a greenfield site. Problem is, it’s on a floodplain and the local planning department is determined not to add to flooding problems in the area. As a result, it won’t grant permission unless you can prove the rain run-off will be no greater than the fields the centre is built on. Your best hope could be to go green, with the Kalzip Nature Roof - a roof covered with hardy plants that will store rain. A Nature Roof holds around 60% of rainfall on the roof, allowing it to evaporate. Building a green roof is not particularly difficult. The Nature Roof fits on top of Kalzip’s well-established standing seam roof system, and will work at up to 30 degrees of pitch. The standing seam roof is the usual layer of insulation topped with aluminium sheets whose upright edges are clamped together for a completely watertight surface uncompromised by any holes or screws. The trick is the rainwater reservoir mat, which is made up of hundreds of small cups arranged like a large egg tray. When the cups are full, rainwater spills over and drains away through the eaves and guttering. A planting substrate covers the mat. This is a layer of fire-blown clay that looks and feels like cinders. At 75kg per square saturated metre, it’s a third as light as simple grass or turf roofs. The roof is planted with a mixture of young sedum plug plants, low-growing perennials that live in rocky soils and can tolerate extreme conditions. The filter web stops plant debris clogging up the gutters. Instead, dead flowerheads and leaves blow away. There’s no need for watering and maintenance involves a visit once a year by Kalzip to apply a liquid plant feed and spray any diseased areas. Obviously, it’s more expensive to install a Nature Roof than just a standing seam system – it will double the cost – although installation is fast and simple. But with extreme conditions bringing more stringent planning controls over drainage, a green roof may be the only way to get your project built.
Enquiry number 206
Run-off research
Current best practice is to build a roof so that water lies on it for as short a time as possible. Even ‘flat’ roofs have some degree of pitch, while sloping roofs shed water almost as fast as it lands. However, the increase in flooding in the UK and mainland Europe has led to suspicions that quick shedding of water from the built environment, coupled with heavier rainfall, is overloading drainage systems. The Building Research Establishment has launched a Partners in Innovation project to come up with guidelines on techniques required to cope. The BRE’s Gerry Saunders says the project will look at how roofs affect the whole environment. “There may be an argument for keeping water on a roof in certain areas,” he says. The built environment may need to become more imaginative at finding ways to reduce the rate and quantity of run-off. Greater rainfall would also imply the need for stronger weatherproofing measures, with thicker membranes, heavier flashing, more rigorous detailing, higher upstands and so on. The degree of slope on a pitched roof may also need to be steeper.A roof in three weeks
Taylor Woodrow’s installation of 10,000m2 of TopDek single-piece roofing panel earlier this year on a new Tesco supermarket in Doncaster gave a watertight roof in three weeks – just over half the time it would have taken with a traditional, layered construction. TopDek, from Ward Building Components, is a one-piece roof panel that combines a 1.2mm single-ply PVC outer membrane with a firesafe-protected core and a steel deck. The panels are fixed to Ward’s Multibeam purlin sections. Dick Janney, Taylor Woodrow customer service director, reckons that the installed cost of TopDek and built-up roofs are similar, at around £27 per square metre. But he rates speed as one of TopDek’s prime benefits. “It only has to be screwed down once,” he says. While faster materials will always attract a construction manager’s attention, TopDek also has safety benefits. Installation is a one-pass operation, so it creates an instantly safe roof. The weather poses fewer problems for laying TopDek as there’s no liner to be blown away in high winds. “Hail, rain, snow – it really makes no difference at all,” says Eddie Hilditch, contracts manager at Cobsen Davies Roofing, who has installed TopDek on two Tescos so far. Taylor Woodrow ran acoustic tests on the panel, fearing the single-piece build would act as a drum in the rain. It didn’t. It was airtight too. An air leakage test gave the Doncaster store a rating of 1.56m3/hr/m2 compared with the maximum leakage of 10m3/hr/m2 laid down by the Building Regulations.
Enquiry number 205
Supplier news
Source
Construction Manager
Postscript
For more information on a product, go to www.construction-manager.co.uk/enquiries
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