Light gauge steel is the generic term for galvanised steel sections formed in a cold process by rolling. They are generally between 1mm and 3mm in thickness, and measure anything from 100mm to 150mm in depth if they are to be used for wall sections and 150mm to 300mm for floor joists.
Such sections have traditionally been used in light industrial buildings, but are increasingly being specified as part of a system either for new build, refurbishment or building extensions.
Many companies working with light gauge steel prefabricate the sections into panels for a variety of uses including internal walls, roofs, cladding systems and entire housing units.
These panels or systems can be constructed from a kit of parts to any size within the structural constraints of the material.
Light gauge steel has been successfully used in the domestic housing market for more than five years. A recent SCI study concluded that construction time could be cut dramatically. There is also far less 'call back' to make good minor cracks caused by settlement or shrinkage.
Four companies in the UK currently produce domestic steel frame systems: Ayrshire Metal Products; Metsec, which makes the Metframe system; Ward, which has developed Speedframe; and British Steel, maker of the SureBuild system. Most of the volume housebuilders have yet to commit themselves to steel framed housing, but Taywood Homes has incorporated the SureBuild system into its housing portfolio.
Metsec director Erle Andrews says: 'There is a big future for steel frame housing in the long term.' However, this sector accounts for just 10% of the Metframe sales. Andrew says that in the short term the company is focusing on flat developments as well as hotels and student accommodation.
'The loads are higher in flatted developments, so they need more material,' he explains. 'Commercially it makes more sense for us to attack the flat market.'
Metsec's system includes steel stud panels that can be used as load bearing internal walls or for external walls carrying rainscreen cladding. 'We are getting a lot of reaction from architects where we use load bearing steel studding as an alternative to blockwork for walling,' says Andrews.
These internal walls are designed to be combined with dry lining, so the construction process becomes one of joining together factory-produced components.
Since 1996, Metsec has successfully sold light gauge steel panel systems into the hotel market, including a rewarding relationship with the Holiday Inn chain. The load bearing internal walls support composite decks made up of permanent formwork and in situ concrete; and internal panels offer the required high levels of sound insulation.
Some hotel chains have opted to accept a longer lead-in time in return for a dramatic reduction in the construction period and higher levels of factory production, and both Granada Travelodge and Forte Posthouse are now procuring hotels built using modular systems.
Light gauge steel is used for the basic frame of the modules, which are assembled in the factory and fitted out with services, carpet, bathroom pods - even the furniture and minibar.
Terrapin has just completed an order for 300 bedroom modules for Travelodge. Managing director Nick Whitehouse says the firm has invested heavily in equipping its Milton Keynes factory with specialist machinery to build the modules, including jigs that can turn a roof or floor section over to work on both sides at the same time. He admits: 'There is a longer lead-in time when we start a new project because, when you're producing something in a factory, you have to have all the detailing completed before you start. But once we're up and running we soon catch up.'
Whitehouse says modular techniques already use 'lean construction' principles. 'Most of the key recommendations in the Egan report are already being applied in prefabrication: lack of wastage through control of materials; efficiency of the supply chain; a controlled environment for manufacture.'
His views are echoed by Yorkon marketing manager Andrew Atkins. 'Sir John Egan's report has been to our good because it is proof of what can be achieved through modular methods,' he says. 'We've seen a lot more interest from a variety of areas.'
Yorkon - a subsidiary of Portakabin - supplies fully fitted out bedroom units to hotel chains, and also builds fast food units for McDonald's which are supplied complete with catering equipment, tables and chairs.
The company has just won a contract to provide 30 modular houses for a development in Hackney, east London, for the Peabody Trust. The five storey Murray Grove is the first modular housing development in the UK.
In 1997 the Peabody Trust invited young architects to submit designs for the site. The competition was won by Cartwright Pickard with a design that openly expresses the modular construction, with lightweight precast concrete balconies, steel cable cross bracing and a clay tile facade fixed to an aluminium support structure.
The 8m by 3.2m by 3m high modules will be fully equipped with plumbing, electrics, doors, windows, bathroom and kitchen fittings, tiles and carpets. They will be delivered to site by lorry in the spring. The main contractor on the job is Japanese firm Kajima.
Light gauge steel frame and modular construction firms are watching Murray Grove with keen interest. If the project is successful, it may well herald a boom in prefabricated steel construction for the next millennium.
Space to grow
Architect Adrian James chose lightweight steel frame techniques for the house he recently designed for himself in Oxford. 'I drew it up so that it could be done in steel or traditional blockwork,' he recalls. The two options came out at roughly the same cost, but James opted for the steel frame because of the speed of construction.
The three storey house sits on piled foundations which extend into the river on one side. It has large open rooms on all three floors, and a curved roof. The brick cladding is supported off the foundations and tied into the lightweight steel frame.
James used Metsec's Metframe system and says both the speed of construction and quality of work were 'very good'.
He believes steel framed housing has not taken off in the UK because it has so far only been used to mimic existing house types. 'Where steel comes into its own is with big rooms in the roof,' he says.
'It gives you the freedom to have open plan rooms and big spaces because there are no trussed rafters. The challenge is to produce houses with
'kerb appeal', and I think steel can do that.'
James is working with British Steel to develop new house styles for the SureBuild system.