Steel sets the standards in building

An Irish company has joined forces with a British firm to introduce a new building system particularly suited to apartment blocks, hotels and offices. It involves the use of galvanised steel joists and studs that assemble like timber framing but which are strong enough to support concrete flooring.

"You have a fast-track system but you can still have the concrete floor. You have a timber frame approach but the sound-deadening of concrete," explains Gerry McCaughey, managing director of Woodroe Ltd.

Woodroe is better known as the timberframe construction specialists, Century Homes, of Monaghan. It trades as Century Steel Systems for its steel frame activity, in partnership with its British steel section suppliers, Metsec plc of Birmingham.

"We were surprised at the level of activity for it," says Mr McCaughey. The company had not yet initiated a marketing drive for the system, he says, adding: "We are actually six months ahead of where we thought we would be."

Projects so far include two office blocks at the Plassey Technology Park in Limerick, two apartment blocks in Naas, and the Killarney Court Hotel, a 100-bedroom hotel in Killarney, Co Kerry. The company is pricing a Dublin project involving eight apartment blocks and another large project in Kilkenny.

The system is a substitute for conventional reinforced concrete construction, which has had little competition in buildings where concrete flooring was required for sound-deadening, as in hotels or apartment buildings. Metal framing is much less attractive in the domestic housing sector where this level of deadening is not required.

Timber could actually be used in specially designed framing that would support the weight of poured or pre-cast concrete floor elements but the expansion rates of wood and concrete are significantly different, says Mr McCaughey. There were no such difficulties with steel and concrete. "We do the engineering and design here and get the steel in the UK," he says.

Woodroe takes architectural drawings and converts them to allow for the steel frame approach. These are put together on a computer and these files can then be downloaded directly to Metsec's computers. The metal sections can then be quantified and prepared for shipment to Ireland. Conventional foundations are poured and "ringbeams" are anchored to them. Internal and external wall framing are then assembled and screwed into place, with these C sections carrying all of the weight above. Prefabricated rigid board insulation panels of 35 mm or 50 mm thickness can be attached to form external walls and these can have conventional plasterboard bonded to them. Internal walls can also receive the standard plaster board finish.

Metal decking which spans between loadbearing members is fixed into place and concrete can then be poured directly onto these sections to provide a standard 160 mm floor. It is possible to assemble the entire building and then pour the floors or to pour the floors as the decking is put in place, says Mr McCaughey.

Any external finish can be achieved, including single-skin block or brick work, metal sheeting or stone cladding. These are bound to the building using metal ties. Mr McCaughey says he has no hard figures comparing the cost of reinforced concrete construction with his steel framing system. Information from builders who have used the system suggests savings can be made, he says. "They are getting more volume done in the same amount of time."

While material costs might be higher, labour costs would be reduced because of the accelerated completion time on site.

"A lot of the advantages are not just related to the cost savings," he says. Builders using the system have the advantage of a "fast-track" construction method but the potential for concrete sound deadening. Components could be prefabricated for final assembly on site. Sites could also be kept much cleaner because there was virtually no wasted material.

Aside from the steel sections, most of the additional construction materials, such as insulation or plasterboard, can be sourced in Ireland. The framing also allows simple installation of cabling, heating and plumbing.

The system is approved in Ireland for buildings of up to four storeys, although it could be used on taller buildings if new approvals were sought. "The apartment construction business is actually crying out for this," says Mr McCaughey, which he expects will be a growth sector for his company.

The idea for the steel frame work, which began 18 months ago, grew as a natural extension from the company's experience since 1990 in the timber frame business. Woodroe was investigating the potential of steel framing, given growing markets for the technique in the US and Australia. Mr McCaughey visited 20 suppliers in Britain and the US looking for a partner before agreeing a venture with Metsec.

Woodroe employs 125 people at its base in Monaghan where it assembles timber frame components and roof trusses in a 60,000 sq ft industrial unit which is currently being expanded to 80,000 sq ft. By mid-October it is scheduled to open an additional 21,000 sq ft facility in Dungarvan, Co Waterford. "We are building the capacity so either plant can take on the metal framing," Mr McCaughey said.