Where offsite works: Mad dash for the loos

How long does it take to build a 250,000 sq ft office and retail scheme behind 120m of retained facade in London's Regent Street? Well, either 96 weeks or 89 weeks depending on which programme you are working to.

This is a joint-venture job between developer Stanhope and construction manager Bovis Lend Lease, so the shorter programme length gets a fancy name: the Vision Programme. In the old days, you might have said there was a bit of fat in the programme, the difference being that nobody told the client back then.

What the Vision thing meant for joinery contractor Swift Horsman was that it was a chance for it to trial offsite methods. It is supplying five disabled bathroom pods and a flatpack version of a volumetric room, called Podwall, for the larger toilet blocks and for welfare facilities. "We selected the Regent Street job to try it out because Stanhope and Bovis tend to push innovation as much as possible where other parts of the industry are very traditional so you wouldn't suggest it," says Matthew Roberts, an asssociate director.

Rather than crane in a complete bathroom, the Podwall elements can fit in the hoists and moved to position on wheels. This allows for greater flexibilty than a volumetric solution.

Podwalls are made from a Metsek light steel frame with an internal skin of Fermacell drylining. They arrive on site tightly wrapped to protect the finishes and fittings. All plumbing and electrical work happens in the factory and is tested and certified by the specialist contractors of those packages so that they can be 'plugged in' once on site.

The cost for both permanent and temporary elements is within what it would have cost with traditional methods. Swift Horsman buys back the welfare wall modules at the end of the project for 30% of the original cost and then refurbishes them. Swift's contract is for £1.5m.

Offsite should decrease the risks of accidents because more of the carpenters are working in a controlled factory environment. Roberts reckons there are six to eight joiners on the Regent Street site as opposed to between 20 and 30. Time on site for a bathroom drops from eight weeks to two days. Quality should also be higher, with less snagging.

Building the bathrooms offsite has other positive impacts on the programme. Architect, client, and whoever else needs to can visit an early mock-up in the factory and agree the finishes. There's also the issue of whether elements fit together. "The architect may be trying to bring together components he's seen in a magazine, or which some salesman has peddled him and they may not work together," says Vince Lydon, Bovis' project director.

This job had changes too. "That glass screen was not as the architect envisaged it," explains Guy Hunt, the Bovis project manager for fit-out. "He didn't like it. It was no problem at all. This system allows a degree of flexibility."

Using Podwall for the welfare facilities means less waste. Normal practice on a job like this is to rip it and skip it each time the facilities moved.

These facilities are much better than you would normally find on site. The doors are birch-faced ply, for example. This contributes to morale, says Lydon. "There is no graffiti on this job. I've never experienced it before," he comments. It's impossible to measure what impact a better environment has on workers, says Lydon, but it must contribute to a more efficient job.

Lydon won't be drawn on what percentage of the £52.25m guaranteed maximum price was spent on prelims, only commenting that Stanhope and Bovis "have considerably raised the bar" on their welfare provision on this and previous jobs such as Paternoster Square.

Regent Street has taught Swift Horsman some lessons, not least "It's not always as easy as it sounds," says Roberts. It has had to learn fast about transportation and lifting. The set-length nature of the modules has also meant corner-cutting has been necessary. The firm needs to overcome that on the next job, says Roberts.

Swift Horsman is talking to other contractors about using Podwall, and is so confident of its success it is leasing a factory in Dumfries and Galloway to cope with its new line of business.

Meanwhile at Regent Street, if the site team hit their Vision target, all will be done and dusted by the end of September. A good performance here is important for all involved since the Crown Estate owns all the properties on Regent Street and has already submitted planning applications to upgrade two more massive chunks of it.