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Theme: doors and windows

As in other sectors, new regulations for disabled access and fire resistance are driving developments in the doors and windows market, but aesthetic considerations and the demand for faster prefabricated units have also brought about innovations

In the welter of government consultation papers that seem to be released every day, the Office of the Deputy Prime Minister has just closed the review of Building Regulations Part M and is now assessing the results. Nestled among the papers seeking the 'response of communities (to) what they think of satellite dishes' and how to 'manage unauthorised camping', Part M emerged to little fanfare. Last appraised in 1999, the regulation deals with access and facilities for disabled people and is playing catch-up with more 'popular' legislation, such as the Disability Discrimination Act (DDA).

Official consultees ranged from the Doors and Shutters Manufacturers Association to the Flat Glass Manufacturers Association, but strangely, of 193 respondents, the Glass and Glazing Federation was not asked.

One of the more contentious changes, which could have implications for specifiers, is the proposed amendment to the unobstructed widths of door openings, according to Chris Waller of Stephen Limbrick Associates.

Amended details of access into buildings other than dwellings (see www. safety. odpm.gov. uk/bregs/consult/access/d10) propose redefining the clear-opening widths. These are described as the distance between the inside edge of the locking jamb and the perpendicular taken from the most protruding point on the hinged jamb - this is usually the outer edge of the door handle of the leaf at 90infinity. Apart from Table 2 increasing the necessary clear widths (to a minimum of 800mm), effectively, this adds another 45mm or so (the distance of the door handle from the leaf face) to add to the clear opening width. Many manufacturers will have to increase standard leaf sizes to suit.

One way to deal with the need for easeof-use of large door leaves for disabled users can be seen at the British Library. Large heavy doors, required for acoustic isolation, are operated by Macwood air-driven door controls from Woodwood Door Controls concealed in the doorframes. These provide silent, power-assisted opening, operated by press switches to hold the door open for a pre-set time. Additionally, the door swing can be triggered by touching the door handle (an architect-designed touch-sensor created by binding silver wire into the leather doorhandle covering).

The conflict between the pressure needed to close a fire door against its seal and the need for ease of operation for people with disabilities must be addressed in the new regulations.

Geze UK's new Boxer range of concealed closers combines double-action door swings with easily variable closing force and a hydraulic latching action, with a fully concealed mechanism - only the guide rail is visible on opening the door. This arrangement also deals with the issue of having to avoid using floor springs in some applications with concrete floors. The visually unobtrusive system comes with the option for electro-magnetic hold-open and freeswing functions, which are suited to applications for the frail, elderly and infirm.

A simpler, but still effective, means of facilitating disabled access without compromising the fire-resistant integrity of a structure is achieved with Fireco's Dorgard acoustically operated hold-open devices.

Fitted quickly and easily on to existing doors, the battery-operated device sits at the bottom of the door with a foot-operated 'plunger' extended to the floor to maintain the door in the open position. As soon as the building's fire alarm system goes off, the sound is detected, the plunger retracts and the door swings closed. This system is ideal for refit or upgrade schemes, since no connection to the mains or intelligent networks is required. Although advice on particular applicability should be sought, the device complies with all relevant standards and has been used on heritage buildings, schools and police service headquarters, among others. The battery has a life expectancy of 12 months.

The eternal difficulty of designing thresholds for inward-opening doors to accommodate wheelchair access without compromising weather protection, has been dealt with in the Stormguard AM3 sill by Sash UK. The manufacturer claims that complete weather protection is maintained under severe conditions. The Stormguard AM5 applies to outward opening doors.

Both are available in aluminium and matt gold finish.

To assist the visually disabled, and also in accordance with the new regulations' aim to protect 'parents with children', Kawneer's Finger Guard door safety feature could be a godsend to those whose children have had their digits pinched in door jambs.

Introduced as a standard option on its 190 robust doors, the Finger Guard replaces the traditional hinge stile with a rounded design - the frame jamb pivots around its centre. A weathered adaptor profile, fitted into the frame jamb, forms the seal around the door stile as it rotates, 'eliminating the possibility of trapped fingers', says David Taylor, Kawneer's product development manager. It is available on single and dual swing doors and does not compromise thermal efficiency on the 451 framing system.

Hidden agendas Discreet fixings are always a much soughtafter architectural means of supporting glazing. They perform their function without intruding into the smooth, clear appearance of the glass. Two recent schemes show how glazing fixings are more acceptable the more invisible they are.

In the first scheme, Metal UK has completed a £300,000 project to design, engineer and install double-glazed entrance facades to six Victorian railway arches in Isabella Street, London, which are being converted into restaurants, bars and retail units.

Each head section had to be curved and the external surface needed to be sheerfaced, with no protruding retaining bolts.

The architect, Allies and Morrison, also wanted the doors to appear frameless and to open fully, so that the units could be used as pavement cafes.

These challenges were overcome with the assistance of Fischer Fixings' new Micropoint technology, which is marketed exclusively in the UK by Metal UK.

'Micropoint is a unique retaining system, which is secured within the glass with an undercut hole, presenting a completely sheer external face, ' explains Metal UK managing director Rod Milicevic. The laminated fixing is ideal for use with double-toughened and laminated glass panels, as it secures the outer pane through the inner pane. The fixing is filled within the inner pane with Fischer's injection anchor, containing a styrene-free, quick-setting, high-quality hybrid resin.

Metal UK's specialist glass manufacturing sister company, Glass UK, created the huge double-glazed units for the project, and Metal UK set about designing the bespoke door system, which also uses the Micropoint technology. All the flexibility of the product occurs within the fixing, allowing use of a far smaller and more discreet bolt (typically 30mm against 50mm for other bolted systems). The product has great demonstrable benefits with monolithic toughened glass.

The £16 million Marriott Hotel in Kensington, west London, due to be opened this month, has the tallest hanging glass facade in Europe. Designed by Moren Greenhalgh Architects, the triangular atrium, which rises 28m above Cromwell Road, contains 200 vertical pieces of 10m Pilkington toughened safety glass, weighing a total of 30 tonnes. The planar fins that support the facade are 930mm, 1,100mm and 3m wide and 19mm thick. Charles Henshaw supplied and fixed the glazing, including the hanging brackets and tension rods.

More than 4,000 specially machined stainless steel Planar bolts secure the glass to the support steel which is, in turn, deflected by 68mm due to the self-weight of the glass.

To avoid stresses on the finished glazing, 20 tonnes of ballast were hung from the roof structure to simulate the finished condition.

This was removed progressively as more glass was added.

Looking back Looking back from today's reliance on proprietary fixings, proprietary detailing and often overworked design, an article on 'Window fixings at the Bauhaus' by Wiltshire architect James Lewis, tucked away in the latest Docomomo report, attempts to piece together scarce information to provide a fuller understanding.

Engagingly subtitled 'Lugs, stubs, brackets, clamps, and concrete dowels and bolts into the concrete', it looks at how window design and construction of the early Modern Movement were created from first principles. Lewis asks: 'How were window elements fixed to early reinforced concrete buildings and how much did the issue of fixing influence design?' Unfortunately, answers are in short supply.

With no surviving detailed documentation about the steel windows, and with darkgrey anodised aluminium replacement windows - though reliant on the original fixings - added to all elevations, detective work dries up quickly.

Lewis is forced to conclude that 'it was the absence of power tools that probably contributed more to structural innovation, ensuring as it did, that what was done was integrated into the construction process'.

Essentially there are three Bauhaus window conditions: conventionally fixed to brick openings, face fixed across concrete columns and curtain walling. Similarly, the three fixing types are steel lugs into brick joints; lugs and brackets; and bolts and clamps. Given that Gropius knew of Crittall Windows' 1926 lug-fixings, designed for brick coursing, Lewis states that the iconic three-storey curtain wall had to be more experimental.

The originality of the design demanded new solutions, and Lewis contends that even the design and fixing were integral to the overall concept; a dialectical relationship between aesthetics and buildability. Curtain wall brackets were bolted to the concrete directly but 'without the use of cast-in lugs, brackets or stubs or other intermediary device'.

Although not sufficiently rigorous to merit the title 'academic'; the article is certainly thought-provoking, quirky and generally entertaining.

Hot stuff Harmonised fire test standard BS-EN 16341:2000 imposes more stringent performance standards on fire doors, currently regulated in the UK by BS 476: Part 22. Although the final temperature of the furnace after halfhour and one-hour tests is the same, the test specimen is exposed to a higher temperature for a longer period of time. Importantly, during the test, the greater part of the door is under positive pressure, easing the lock/ latch zone away from the frame and making the requirements for integrity of the seal more onerous.

Shadbolt has already embarked on a comprehensive test programme on all its doors, to suit the new standard, and has carried out 18 full-scale tests and 25 small-scale tests covering all aspects of hardware and glazing, even though Part II, dealing with ironmongery has not yet been ratified. In some cases, Shadbolt doors have exceeded test criteria for 30- or 60-minute by up to 50 per cent.

A comprehensive guide to regulatory requirements, testing methods, the Construction Products Directive, glazed apertures, intumescents and many other key issues is combined in The Best Practice Guide to Timber Fire Doors from the Architectural and Specialist Door Manufacturers Association.

Authors Louis Hardy and Lin Parry's work should prove a useful reference source. It is priced at £25 and is available from ASDMA on 01494 447370 (www. asdma. com).

Fast tracking Technal's new GXi sliding balcony doors have found their way on to Cartwright Pickard Architects' latest foray into modular housing with Yorkon, for Yorkshire Housing in York - a four-storey block of 24 highquality apartments.

Opening out on to timber balconies, the doors were fabricated by Securefront Systems and installed off site at Yorkon's production centre. Tested to 20,000 openand-close cycles, GXi has clean, narrow sightlines, a 9mm flush polyamide thermal break for performance in line with Part L, and the option of flat-faced or curved profiles. The steel-framed apartment modules were then craned into position at Sixth Avenue, complete with bathrooms, kitchens, doors and windows, compressing the programme to just 15 months from inception to completion.

Another fast-track prefabrication application involves the construction of Liverpool's first-ever five-star hotel. Fullyglazed fixed-light windows, comprising 8mlong prefabricated concrete panels, were made by Airedale Glass and Glazing in Leeds and installed into the panels off site in a factory in Cambridgeshire, improving accuracy and quality and significantly reducing the build time. The 8m-long pre-finished, white, acid-etched panels were then craned into position on site in Liverpool.

The 10-storey hotel is part of the £55 million flagship Beetham Tower development on the site of the former St Paul's Eye Hospital - the largest building project currently under way in Liverpool - which is due for completion in spring 2004. Designed by Aedas AHR and built by Carillion, the tower will provide 126 apartments and nine exclusive penthouses.

Airedale Glass and Glazing (www. airedaleglass. com) won the £1.5 million contract for the scheme in partnership with architectural-aluminium systems specialist, Technal, using 330 Fxi46 casement windows for the hotel and the tower. The project also includes 1,800m 2of Technal's MC facetted curtain walling The windows for the apartments use a specially adapted heavy-duty section to meet the wind-loading requirements for the tower. They achieve more than 2,000 Pa for wind resistance and 600 Pa for water tightness, and use an efficient flush polyamide thermal break.

Off-site production of another sort includes the supply and fitting of prefabricated units into building shells, from bathroom kits to kitchen modules. The benefits of specifying prefabricated doorsets have long been recognised on health-authority projects; fitting a fully fire-tested finished unit into prepared openings saves time, ensures performance and simplifies the supply chain.

Now LS Leaderflush Shapland has supplied doorsets to Hull Royal Infirmary maternity department, incorporating ironmongery as part of the package, and including manufacturers' warranties of up to 25 years to suit PFI projects. Furthermore, acoustic doorsets from 28dBRw to 49dBRw can be achieved with the same leaf thickness.

Fully finished windows offer another way of compressing site programmes. Joinery specialist Premdor, based in Hedingham in Essex, has installed a range of spray booths and drying equipment so that it can factoryapply Becker Acroma's wood finishes to its products. Using the full range of Laqvin high-performance water-borne exterior joinery coatings, developed to suit northern European climates, it provides a smooth, durable finish in factory conditions, for immediate installation on site. The typical finishing specification of primer and topcoat comes with an eight-year guarantee.

In a more traditional approach to supply and manufacture, contractor Senlac Windows and Doors has just completed the installation of W20-section steel windows at Suncourt House, a five-storey office block on Essex Road in north London. The building is in a conservation area, and exact copies of the original pre-war window units were fabricated from measurement and photography prior to building works.

Working from full-height scaffolding, Senlac's operatives assembled the individual window units to infill the large openings in the main elevations. The new units incorporate 4/6/4 sealed double glazing and have been given the dual corrosion protection of a Charcoal Grey polyester powder coat on the hot-dip-galvanised steelwork.

A new Specifiers' Guide to Steel Windows is available from the Steel Window Association on 020 7637 3571 or by visiting www. steel-window-association. co. uk.

Achieving closure Maintaining a robust seal is essential to compliance with Part L of the Building Regulations. A new generation of weather seals using 'a unique, environmentally responsible water-blown extrusion process' is about to emerge from the new 56,000m 2UK production facility of Linear, in North Yorkshire.

Foam Tite is made from Santoprene thermoplastic vulcanisate (TPV) foam. The soft closed-cell foam has a tough but flexible homogenous skin, which has been shown to absorb just 2 per cent of its 'body weight' after 24 hours' total immersion in water.

Advanced Elastomer Systems, an affiliate of ExxonMobil and world leader in TPV, says that the material offers 'excellent weatherability and flex-fatigue performance, as well as outstanding ozone and chemical resistance'. It is also co-extrudable, heat weldable and recyclable.

Checking compliance New European testing methods for measuring the U-value of roof windows have just been adopted across the EU, allowing exact comparison between manufacturers. Velux already measures its product to the new standard EN ISO 12567-2, giving a guaranteed U-value of 1.6W/m 2K for the whole window.

A new series of practical guides to timber windows has been published by the British Woodworking Federation, covering, inter alia, thermal requirements of Part L, Uvalue certification, care and protection of windows on site and sealant recommendations. Guides cost £2 and are available by telephoning 020 7608 5050 or emailing bwf@bwf. org. uk.

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