Open and shut case

£600 per scratch? That's cheap

Renovating windows can save on costly reglazing

Windows are among the first elements to get fitted in a building. Which is one of the reasons why, by the time the building is up and ready for the client to take control, they can sustain some very expensive damage. As each successive gang of workmen gets to work on their respective jobs, windows can get broken, cracked, scuffed, scratched and spattered with paint spills and weld splashes.

Paradoxically, even the final builder's clean can damage windows. "Projects employ the finest architects, the top construction companies and the best craftsmen, then they go and take people off the street, give them a rag and a scraper and say, 'Get cleaning'," says Tony Gribble, sales manager of Glass Renovation.

"Whatever the reason the result is scratches on the windows. And as new glass is so soft – it takes time to harden off – a poor builder's clean does a lot of damage."

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So what can construction managers do? Replacing damaged windows will inflate construction costs, particularly if the windows are embedded in a frame that also has to be removed and possibly repainted or retreated. And with the lead time for some types of glass taking up to 13 weeks, the project itself could be unacceptably delayed, particularly as repairing the glazing is often a last minute thing.

The use of flame-retardant glazing protectors to prevent damage in the first place is widespread. But protectors aren't fail-safe. "They can be blown off by the wind, or a tradesman might rip one off to take a look at the view," says Anton Winkler of glazing specialist Seele. "And the cost of damage can be huge. Replacing a pane of glass can cost 10 times as much as it costs to install it in the first place."

Alternatives
In the high street, the use of prestigious display windows makes replacement particularly expensive. "Some of our shop windows cost over £3,000," says Dale Higgins, projects manager at fashion retailer Karen Millen. "The management won't live with a scratched window. But you can't make an insurance claim on a scratch – the glass has to be completely smashed. That makes Glass Renovation invaluable – they only charge £600 to get a scratch out."

Winkler does not believe damaged glazing is a big problem for the construction manager. He puts the proportion of damaged windows on a recent Seele project at just 0.2% and says it is really the problem of the glazing contractor or fitter-out, although he admits it doesn't always work out that way. In practice, even just one damaged window can threaten the timetable for handover.

Obviously, if glazing is cracked or broken, you have no choice but to replace it. But for windows that are only damaged superficially, it is possible to grind and repolish the surface of the glass.

Essex-based Glass Renovation charges nearly twice as much per day as its glass repolishing rivals, but claims to be five to six times more productive. How come?

Supercharged
"We supercharge our grinding machines," says Gribble. "The machine is made in the US, but we've developed it further. We reckon we've made it 30 to 40 times faster. And we put a lot of effort into staff training. It's a combination of technology, methodology and expertise."

The grinding machine is attached to the face of the pane with suckers rather than moving it to and fro freely over the window. The jets of water that cool the glass as it heats up under polishing are also fixed to the grinder, so operatives don't have to hose it down manually.

Robert Porter, project manager for commercial office building Mid City Place in London's Holborn, had used a glass polishing firm on another job and wasn't impressed. "There was extensive visual distortion where they'd polished the glass," he says. "It looked like a fish-eye lens. We used Glass Renovation to repolish 20 to 30 damaged panes in Mid City Place and they were a lot better. They were quicker and cheaper, and the results were far more acceptable."

Steel frames march to a new tune

steel framed-windows rise to new part l challenge

For years, steel-framed windows and doors have been in retreat before the all-conquering PVC frame. And in lowering the permitted heat loss for steel-framed windows from 3.3 to 2.2Wm2K, the new Part L implemented last April was expected to bang the last nail into the coffin of steel frames, which trail behind timber, PVC and aluminium for thermal efficiency.

But for steel frame specialist Clement Windows, the new Part L may have been the best thing to happen. It has developed a range of windows, called EB24, with a U-value reduced from 3.3 to 2.1 for opening casements and 1.8 for non-opening casements.

The depth of the double-glazing unit has been increased to 24mm, compared with 14mm or 16mm for most units. The sightlines remain the same because the company increased the depth rather than the thickness of the frame.

"Windows have to be Part L-compliant," says Paul Trace, group development manager for Clement Windows, "otherwise you get into thermal trade-off complications. Steel used to be a niche material, for listed buildings and the like, but EB24 opens up new build to steel."

Having made up the thermal deficit, steel windows now offer a robust alternative to PVC. Modern steel frames are galvanised so they won't rust, weather-stripped so water can't get in, and factory-painted with a polyester powder-coating so they won't need painting for the first 10 years. "Basically, a steel window will last the lifetime of the building," says Trace.

While local authority building regulation officers appreciate their low maintenance costs, conservation officers like them because they match the original design of much social housing. Many listed buildings are also required to use steel frames.

In converting the old Tramshed in Bath to housing, HBG's project manager, Rodney Northwood, had to replace all the old steel frames. "Many of the frames had completely rusted away," he says. It took four visits from Clement Windows to replace all the steel-framed windows.

Nearly all steel windows are made from recycled steel and can in turn be easily reused, unlike PVC.

Maintenance adds to PFI costs

cost of lifetime maintenance moves up the agenda

A concentration on purchase and installation costs comes naturally to construction managers, but this is no longer enough. With constructors obliged to maintain the building for 25-odd years in PFI projects, and maintenance moving up the agenda in social housing, lifetime costs can't be shrugged off.

"All construction companies are at different stages of lifecycle understanding," says Alex Brown, managing director of Scandinavian timber doors and windows importer Janex. "Contractors aren't experts in windows and doors, we are, and we want to form partnerships to focus on savings, lifetime costs and efficiency. Long-term relationships make it easier to plan ahead and control costs."

Construction and civil engineering contractor Gleeson built four schools in the Scottish Highlands under a PFI partnership for which Janex supplied the windows and doors, which are guaranteed for 25 years. Unlike the tender market, where the construction specifications are already written, PFI schemes require the builder to design the structure. Accordingly, Gleeson involved Janex eight months before the job started to bring its specialist knowledge to the project.

"Janex helped us a lot with information on specs and installation," says Gleeson buyer Graeme Hornal. "That's what we'd expect from a key partnering supplier. For example, the architect had asked for fire-rated doors in certain areas, but Janex pointed out they weren't needed because they were sited in a fire-rated corridor. Dispensing with the original door spec meant a massive price saving for us."

Over half Gleeson's business now comes from PFI and the company is convinced that bringing in pre-construction expertise is a successful strategy.

Janex has also teamed up with the Timber Research & Development Association to measure the lifecycles of doors and windows as a whole, rather than just the componentry, such as the handles and hinges.

While PVC's dominance in the UK window market was built on a perception of low or no maintenance, some customers have come out against plastic because little can be done when it discolours or breaks.

The result is a renewed interest in wood. Brown says poor design and inferior material are things of the past. "We've designed out rot using composite materials," he says. "We use aluminium for the sills and introduced proper air circulation and water drainage. Timber windows are sustainable and can be repaired.

Hard core to social housing doors

Fibreglass facing adds insulation and durability

When it decided to replace 2XG timber front doors in its 7,000-odd properties, Chelmsford-based social housing provider Chelmer Housing Partnership chose Doorman composite doors from Door Panels.

It is expected that the number of doors replaced under the contract will eventually run into the thousands.

Peter Scales, building maintenance surveyor at Chelmer, says good looks and high levels of insulation and durability were the big attractions.

The Doorman's polyurethane core gives a high level of acoustic and thermal insulation. A solid Doorman has a U-value of 0.6, while a half-glazed model is rated at 1.4, compared with 3.7 for a 44mm-thick solid oak door.

Wood effect
The timber frame is faced with 2mm of wood-effect fibreglass, which is available in a range of colours. The doors look and feel like a traditional timber door, but they don't require painting, varnishing or regular maintenance.

The fibreglass "skins" are also designed to resist denting, warping or cracking from exposure to the weather.

"We trawled the market and couldn't find anything better," says Scales. "The finish is colour-fast, strong and resistant to impact. The embossed timber effect looks much better than flush-face doors. We also wanted a product that would be maintenance-free, so there would be no subsequent damage to wall renderings or facings."

Security is also a big selling point. People worried about break-ins wlecome feeling safer.

The Doorman has a multipoint locking mechanism, high-strength hinges, steel latch lock and anti-drill key barrel as well as a double rebate. It also uses a reinforced PVC frame, so it won't be shattered by a determined assault in the same way that timber would.

"The Doorman has a PAS 23/24 security rating on the strength of its locking and the kind of damage it can take," says Martin Dickie, regional commercial manager for Door Panels. "That is a police-endorsed benchmark and external doors on all new-build social housing have got to have it."

Project managers need to keep in mind buildability, or the ease with which components can be assembled on site.

The Doorman comes as a completely finished doorset, with adjustable hinges to simplify installation.

As with PVC doors, installation is easier than with timber doors because the overlapping of the frame by the door gives fitters more leeway when they come to fit the door.

"There is a very good turnaround time," says Scales. "They manufacture all the doors within three or four weeks of the survey and they fit each door within a day. We've had to call them back just twice to adjust the doors slightly when tenants couldn't open them properly, but they resolved the problem straight away, fixing it the next day."

Finance deal
By the end of the year, Door Panels should also be able to unveil a finance deal for local authorities that will allow them to replace doors (and windows and roofs, as the company is part of the Heywood Williams Group) within a five-year period but pay for the work over 15 years.

Another division, Mila Maintenance, can also offer long-term maintenance of all external works for an annual fee.

The heat is on frames

insulated frames help meet new part l for PVC windows

The heat is on to reduce the amount of warmth that leaks out of buildings. "Six months ago the new Part L lowered the permitted U-value of PVC windows to 2.0, while in Scotland it will drop to 1.8 next March," says David Strang Sheerframe product director at British PVC system manufacturer LB Plastics. "If, as seems likely, the rest of the UK follows suit, manufacturers of window frames will have their work cut out trying to achieve it."

The frame is the least thermally efficient element of a plastic-framed, metal-reinforced window because the chambers of the frame are filled with highly conductive steel or aluminium bars that give structural strength to the window. While most manufacturers can demonstrate Part L compliance for a simple window, the more complex structure of a typical English window, which incorporates a centre bar, a toplight or a sidelight or all three, reduces thermal insulation because it increases the ratio of frame, with its thermally inefficient metal bars, to glass.

One way to get a window to comply with Part L is to make the glass even more thermally efficient by using low-emissivity products. The most common form of low-E glass is soft-coat, which has special coatings applied to the glass in a vacuum chamber. However, soft-coat glass is costly and easily scratched or damaged.

The other way to make a window Part L-compliant is to make the frame more thermally efficient, which is the approach taken by British PVC system manufacturer LB Plastics.

Plastic blanket
The company's Thermlock system wraps the steel or aluminium bars in the frame chambers in a plastic blanket. The metal reinforcing material is covered with a special thermoplastic compound. The result is a four-chamber frame that has structural strength but less heat loss.

Closing the door on fires

fire door retaining system eliminates wedges and meets new fire regulations

For occupants of buildings, fire doors are a pain. In places such as nursing homes, where every bedroom has a fire door, residents leave them wedged open because they don't like feeling shut in.

The best way to combat the wedge has been to install a fire door retaining system, which holds the doors open until the fire alarm goes off, when they automatically release them. Indeed, the constant stream of fire regulations for residential homes have specified fire door retaining systems for ever more doors.

Retrospective
Such systems are typically wired into fire alarms, but there is a cheaper method. A fire door retaining system called Sureclose can be installed easily, swiftly and even retrospectively without any wiring at all.

Sureclose is a wireless technology in the form of two battery-powered devices: a transponder and a door retainer, both of which are simply screwed onto the wall. One transponder is fitted on each floor next to a fire bell or sounder, and a retainer is screwed next to each fire door that is to be held open. It takes about 15 minutes to install each retainer and transponder.

The system works with existing automatic fire detection and alarm systems. The transponder responds to an alarm by transmitting a coded radio signal to the door retainers to release the fire doors. The transponder is a dedicated listening device with response tailored to the frequency range of the fire alarm. It ignores bogus sounds from vacuum cleaners and other electrical and acoustic interference, and is unaffected by variations in alarm audibility. In wired systems, on the other hand, each retainer listens out for the fire alarm, which may well be far off and confused with other noises.

Sureclose transponders cost £99 each, as do retainers, whereas a wired system will cost around £60 per retainer plus the cost of the wiring and installation, and redecoration, plus another £250 for a fire systems check if it's retro-fitted.

"It should cut about 25% off the labour and wiring costs of a wired system," says Derek Paramanis, senior projects manager of Castleoak Construction, which builds nursing homes in the South East. "We've been wiring up all the fire doors in our nursing homes to future-proof them against more changes to the fire regulations. There are time restraints on normal wiring whereas you can leave the wireless system to the last minute if you need to.

The Sureclose system waits for the alarm to sound for six seconds before it transmits the door release radio signal, and doors are released after a further 12 seconds. Each retainer can be set to respond to an all-door release signal as well as a selective release signal. The doors can also be released manually.