Highwood Court, Harlesden, north London

5/7/2010

This scheme's innovation in design and modern methods of construction makes it a model for urban infill sites.

Prefabrication was an obvious choice when developer-architect SUSD acquired a tight urban backland site. It opted for timber frame to deliver the homes cost effectively, efficiently and sustainably, and was pleasantly surprised at the end result.

Description

Highwood Court in Harlesden is a great location for urbanite homebuyers, but a difficult place to build. The nine-home scheme is in a small courtyard surrounded by buildings, has a single narrow alleyway for access and leads into busy Harlesden High Street.

It was hardly surprising then that developer architect SUSD chose to build in modern methods of construction rather than traditional. The developer also set out with a bold ambition: not by fill the site with apartments, but to build houses, and ones that would be sustainable and not highly priced. The scheme of eight three-bedroom houses and one two-bedroom unit is designed as a tight curved terrace around a courtyard to create a small community where residents can find both privacy and easy interaction. Overlooking is avoided through the orientation of the homes with no windows onto the site boundary.

SUSD's in-house design team specified the Becker-Haus timber panel system and worked closely with the German supplier to come up with a design that worked for manufacture. The timber panels are self-finished and pre-clad with windows fitted, while services are pre-installed into party walls.

The basic homes were constructed over four weeks, including glazing, doors and making structures weather-tight. For buyers, the appeal of the homes comes less from their innovative form of construction and more from their comfort and open plan layouts, terraces and green roofs, and urban townhouse chic. "As a model, this is perfect for inner city infill locations," says SUSD co-founder and director Peter Harris. "There's no wasted circulation space in the house and we managed to achieve great efficiency."

Key features

Solid prefabricated timber construction
Exposed timber on internal walls for a natural finish and simplicity of construction
Low-energy costs. The timber panel system helps achieve air tightness levels that are more than five times standard requirements.
Green roofs
Natural wood fibre insulation, to provide high thermal performance, low energy costs and good sound insulation between floors.
hardwood double-glazed windows
Thermowood Scandavian soft wood decking from sustainable sources, which is steam heat treated at a high temperature. As a result the product offers such advantages as high resistance to insects and fungi
Bicycle storage system.

Project outcome to date

A certificate from the Carbon Bank shows that the Becker-Haus solid timber system used on this project captured 221 tonnes of carbon.

Learning points

When SUSD planned the project, the timber frame appeared extremely cost effective, but changes in the exchange rate pushed up the cost
In spite of the potential for language barriers between the English contractor and German key supplier, SUSD co-founder and director Peter Harris says this turned out to be the most straight-forward build project he'd ever worked on.
The scheme achieved level 3 of the Code for Sustainable Homes. Harris says: "That's because we have electric heating. If we hadn't included that we would have achieved level 4. The homes are unbelievably efficient in winter."
Although German regulations make no requirement for coating, UK fire regulations required the internal wood to have an intumescent lacquer applied for Class 0 protection. "We've had to learn about the product," says Harris.

Project team

Developer/architect: SUSD

Quantity surveyor: PT Projects

Manufacturer: Becker-Haus

Main contractor: Philiam

Structural engineer: KMG Partnership

M&E engineer: WR Associates

Landscape design: Jonathan Cook Landscape Architects and SUSD

Sales agent: Rolfe East New Homes

Images: Photographs by David Grandorge