This week we look at modular building à la mode, including a pre-assembled office system from Laing O'Rourke, a panel design for social housing from Mirus and Countryside's steel-frame factory in Greenwich
Airtight panel-based system
Murus has launched a panel-based building system for social housing, student accommodation and hotels up to six storeys. The company says it has been certified by BRE as a zero-heat system. The wall and roof panels' U-value of 0.15 W/m2°K means that properties built with the system only need minimal heating. The panels can be up to 9 m long and 3 m high because the panel stucture is formed using I-section beams instead of timber. The single-skin system features "reverse wall" construction, whereby the inside of the panel is made from sheathing board, and cladding materials – such as brick slips or render – are attached directly to the outer cement-based particle board. Each panel is filled with recycled newspaper or wood insulation and can be supplied with high-performance Scandinavian doors and windows ready-fitted. The entire structure is built using the company's wall, floor and roof cassettes, making the envelope airtight. Murus has completed an academic building for Durham University and a care home is on site in Ireland.
Murus 305

Modular underfloor heating
Wavin Plastics has added three modular underfloor heating systems to its range of products. The first is called System Plates, and is designed for solid screeded floors. A series of plastic plates lock together to ensure the floor screed material does not slip between the gaps, and the plastic heating pipes are inserted into clips. The second system is suitable for fitting between floor joists. Expanded polystyrene panels measuring 1200 × 340 × 50 mm can be installed from above or below the floor and contain integrated aluminium heat diffusers. L-shaped brackets secure the panels to the side of the joists. The third system is intended to fit over a wooden floor deck and is similar to the joist system, except that the panels are 600 mm wide. These incorporate a plastic film cover to separate the panel from the floor and prevent "ticking" from thermal expansion and contraction.
Wavin Plastics 306

Composite roofing
Integrated Polymer Systems has teamed up with steel firm Corus to develop a panellised composite roofing solution called Superdeck 1000. It has a Corus galvanized steel deck combined with foam composite insulation said to provide 100% insulation over the roof. The entire roof is waterproofed with IPS's Rubberfuse single-ply roofing membrane.
Integrated Polymer Systems 307

Mix-and-match roofing
New company Smartroof has launched a complete panellised roofing solution for homes. It consists of stressed skin panels incorporating a choice of different insulation materials to which the roof covering is subsequently attached. The panels are designed to span the width of the house from gable to gable, so no intermediate structural support is necessary. Measuring either 600 mm or 1200 mm wide, they have an interlocking joint that the company says is watertight. The roof construction starts with a custom-made eaves panel, then standard sections are fitted up to the ridge. Sections incorporating cut-outs for windows can be specified, or alternatively a whole section can be omitted to allow space for a full width rooflight.
Smartroof 312

Secure doorset package
Steel-door specialist AccentHansen has launched a range of high security doorsets called SecureShield, supplied as a package complete with frame and hardware to ensure there are no weak points. Five levels of protection are available, from attempted entry by casual intruders to assault by heavily armed raiders.

The doorsets are also said to be fire-resistant from 90 to 240 minutes, depending on specification, and include smoke control and noise attenuation. They are finished in a high-impact gloss in a wide choice of colours, or in brushed or polished stainless steel.
AccentHansen 313

What’s the spec? Bridge Place, Admirals Park, Crossways, Dartmouth

The staff of contractor Laing O’Rourke have just finished moving into their headquarters building in Dartmouth, Kent. They are the guinea pigs for their employer’s Customised Office Solution, a modular building system that combines fast-track construction, cost certainty and customisation.

At the heart of the process is an integrated supply chain that provides everything from design to fabrication to installation of the pre-assembled units. Rather than designing a standard building plan, the Laing O’Rourke team has designed the most important interfaces between the building’s components. This gives clients a wide choice of building size and specification.

Each office is based around a 9 × 9 m structural grid with a standard storey height of 3.9 m that will accommodate a choice of servicing solutions, such as fan coils, displacement air-conditioning or natural ventilation.

The building’s frame is constructed from precast concrete vertical elements, with post-tensioned concrete floor slabs cast in situ using prefabricated, reusable steel shuttering to save time. The system even incorporates precast concrete-edge shuttering with cut-outs for the steel tendons running through the slabs. These are tensioned 24 hours after the floor is cast.

Components such as the lifts and the cladding frames are standardised. The lead-in time for the 7400 m² building was cut from an industry average of six-to-eight months to four, as so much of the design was pre-decided and standardised. Construction, including fit-out, took 40 weeks rather than the usual 12 months.

The concept seems to have paid off, as a speculative building for developer Land Securities next door has just been completed. Although similar in appearance and size to its neighbour, the building has an atrium and differs in terms of cladding, the services solution and the internal finishes.

Precast frame components
Malling Products 301

Unitised curtain wall cladding
Schmidlin UK 302

Modular lighting
Zumtobel 303

Aluminium louvres
Colt International 304

Project team
Client/main contractor Laing O’Rourke
Architect Reid Architecture
Engineer Buro Happold
Quantity surveyor Franklin + Andrews

Product innovation

Countryside Properties has brought the factory onto site at Greenwich Millennium Village, the housing development near London’s Millennium Dome where it is a joint venture client with Taylor Woodrow. The housebuilder has invested in a cold-steel rolling machine to produce metal stick cladding frames for 120 reinforced-concrete-frame homes, and structural steel frames for another 66 homes. It even made the steel structure of its own shed. By producing components on site instead of ordering them weeks in advance, the construction process is faster and more responsive to fluctuating demand. Transportation costs to site and waste are reduced, and if the project is delayed, there is no need to store previously delivered framing components.

The only deliveries to site are 50 m long rolls of 1.2 mm thick steel. The architect’s CAD drawing is read by a manufacturing program, which then calculates the sizes of the steelwork needed for each room or floor of a development and automatically adjusts the sizes to account for building tolerances. The program drives the machine that cuts the steel to shape and drills holes ready for assembly. The machine also numbers each component so site workers can easily assemble trusses or framing sections by riveting the steel components together. These are then craned into final position.