Timber frame meets defence requirements

A major housing development for the Defence Infrastructure Organisation in Wiltshire is using timber frame kits to help speed up the programme.

A timber frame system is being used to construct 322 homes on a defence accommodation project in the garrison town of Tidworth in Wiltshire.

The system, supplied by Herefordshire-based timber frame specialist Taylor Lane, was selected by housebuilder Hill, working for client the Defence Infrastructure Organisation, because of the speed benefits it offered to the programme.

“We required quick design, mobilisation and delivery to ensure that we achieved the project completion date,” says Ryan Harris, project director at Hill.

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The development encompasses a mix of three and four bed houses, with five different house types. Hill engaged early with the Taylor Lane in-house team to develop the designs for the timber frame kits, which comprised ground and first floor open panels, which were pre-insulated offsite, floor cassettes and roof components. Insulation for the external walls was also fitted in the factory.

“The timber frame designs were fundamental to early commencement of site operations,” explains Harris. “We needed to know the line loads of the timber frame to design the foundations, so we could secure firm costs and make an active start on the ground.”

The houses use strip foundations and Nu-Span precast insulated floor slabs. The thermal performance of the properties will be strong. Taylor Lane’s Thermaline insulation system, used for the Tidworth development, features 120mm-thick PIR (polyisocyanurate) insulation board and foil-faced reflective breather membrane, to achieve a U-value of 0.19 W.m2K.

The Taylor Lane kits arriving at Tidworth and being assembled and erected

The completed houses

The timber kits were manufactured by Taylor Lane, delivered to site and erected over a period of 13 months, with 10 units completed per week over a phased programme. The firm worked on a just-in-time basis, generally working back one week from the delivery date, with the manufacturing process taking 12 to 15 hours per unit.

Taylor Lane contracts manager Liam Hale supervised the delivery and erection of the timber frame kits, managing a team of up to 25 erectors and 300 labourers.

“The greatest challenge for the team was the erection of a pair of three-bed semi-detached houses in one day,” he says. “The build was time-critical as the only available crane position for the plots blocked the main site entrance, and this could only be closed for one day.

“Working with a team of six erectors and one crane, we constructed these houses from three delivery loads – one with the ground floor and first floor panels, the second with the floor cassettes, and the third and final load, with the roof components. All were then assembled onsite prior to erection.”

For the roofs, lifting straps were attached to longitudinal trusses in the pre-assembled structure, which was then craned in to position.

“These longitudinal trusses also serve as part of the roof bracing,” explains Hale. “This approach helped us achieve the build in the limited timeframe.”

The homes will be faced with red brickwork and traditional roof coverings to match the surrounding villages. The project is due for completion this spring.