The prospects for wood

The House of the Future raises the question of the structural use of timber in buildings. Timber scores well on the sustainability scale, provided it is obtained from an accredited source such as the Forestry Stewardship Council. The Weald and Downland Open Air Museum 7 miles north of Chichester is a national centre for the conservation and study of traditional timber-framed buildings. The Conservation Centre explores new techniques in greenwood timber construction. Edward Cullinan Architects in association with Buro Happold Engineers have produced an undulating structure which rhymes with the South Downs landscape. The timber structure comprises a clear span gridshell formed out of a weave of oak laths. The high moisture content of the timber allows it to be formed into the necessary curves and then locked into shape. Once the laths are in place natural drying strengthens the structure. Oak is twice as strong as an equivalent size of other timbers which means that the cross-section of members can be reduced. The longest laths are 37 metres. Unique to the structure is the green jointing of the gridshell laths from freshly sawn oak. It is developments in glue technology which have made this possible.

The structure is set on an earth sheltered masonry ground floor. The lower storey is temperature controlled to safeguard archival material. A central row of glue-laminated columns supports the floor of the workshop.

This is the first timber gridshell structure in Britain and should become an icon of sustainable construction (Figure 8.7).

An even more ambitious gridshell structure is taking shape in Savill Garden in Windsor Great Park. Architects Glenn Howells won a competition for a visitor centre with a wave form grid structure that

Weald Down Visitor Centre

differs from the Weald and Downland building in that it is raised above ground, allowing panoramic views of the park. It will be the largest grid-shell structure in the UK at 90 m long and 25 m wide. The structure has been designed by Buro Happold, the engineers involved at Weald and Downland, using 80 by 50 mm larch timbers harvested from the Park with oak forming the outer rainscreen.

As a research exercise in multi-storey timber buildings, the Building Research Establishment Centre for Timber Technology and Construction has built a six-storey timber-framed apartment block as a test facility in its vast airship hangar at Cardington (Figure 8.8). The results of the tests may well have a profound impact on the house building industry. The building comprises:

• platform timber frame;

• timber protected shaft;

• single timber stair and lift shaft;

The report on the project concludes:

This high profile project has provided a unique opportunity to demonstrate the safety, benefits and performance of timber frame construction technologies. This project has brought all aspects of construction together, including Regulations,

Figure 8.8

Building Research Establishment experimental timber-framed apartments

Figure 8.8

Building Research Establishment experimental timber-framed apartments

Bre Garston

Research, Design, Construction and Whole Building Evaluation. Many Building Regulations, codes and standards are being updated as a result of this project. It has been the most challenging and exciting opportunity to obtain technical backup data for promotion of timber frame in the last 20 years and it has been recognised as one of the most valued projects (Enjily, V. (2003) Performance Assessment of Six-Storey Timber Frame Buildings against the UK Building Regulations, BRE Garston)

A tour de force of timber construction is the recently completed Sibelius Hall at Lahti in Finland. This concert hall epitomises how timber used both as a structural and sheeting material can produce a building great elegance and beauty. It is a testimony to the mastery of timber developed by the Finns over the centuries and serves to exemplify the versatility of this material as the ultimate renewable resource for construction. The architects are Hanna Tikka and Kimmo Lintula.

As well as being a renewable resource, timber also has a good strength to weight ratio, which is why it was used to construct one of the most famous aircraft of the Second World War, the Mosquito. The designers of this aircraft pioneered timber monocoque construction in which the skin and framework as a unified whole coping with both compression and tension. The advantage is this system is that it can accommodate curved and flowing shapes combining lightness with strength. The main structural element is laminated veneered lumber (LVL) typically

Experimental Structures Glue Laminated

Figure 8.9

Roof formation, the Maggie Centre, Dundee (courtesy of RIBA Journal)

Figure 8.9

Roof formation, the Maggie Centre, Dundee (courtesy of RIBA Journal)

Figure 8.10

Maggie Centre, Dundee. RIBA Building of the Year for 2004

Figure 8.10

Maggie Centre, Dundee. RIBA Building of the Year for 2004

Figure 8.11

Winter Gardens, Sheffield 2002 (architects: Pringle Richards Sharratt)

made from Norwegian spruce. It can be produced in sheets up 26 m long by using staggered and scarf jointing.

Timber can even accommodate the fluid imagination of Frank Gehry. LVL was chosen for the roof of the Maggie Centre in Dundee. It is finished in stainless steel (Figures 8.9 and 8.10).

The Winter Gardens form a spectacular element of the 'heart of the city' project for Sheffield (Figure 8.11). It is conceived partly as a glazed street in the spirit of the galleria connecting with the wider urban structure. It opens at right angles to the Millennium Galleries that also integrate a pedestrian route with gallery and restaurant provision. The contrasting space and architectural expression of the two buildings achieve the height of the poetic in urban terms. The most striking feature is the laminated larch parabolic arches which support the glass skin forming a counterpoint to the trees within. Larch was chosen for its

Figure 8.11

Winter Gardens, Sheffield 2002 (architects: Pringle Richards Sharratt)

Wooden Parabolic Arch

durability and minimal maintenance characteristics. In time it will turn a silvery grey.

The space is 65.5 m long and 22 m wide and designed to accommodate a wide variety of exotic plants, many of which are under threat, in a frost-free environment. Underfloor heating in winter is provided by the city centre district low grade heating scheme. In summer surrounding buildings will provide solar shading. Vents in the roof and at both ends of the building encourage stack effect ventilation. Trees such as Norfolk Island Pine and New Zealand Flax occupy the highest central zone of the space which rises to 22 m. For the citizens of Sheffield it has been a spectacular success.

A useful guide to designing in timber is provided by Willis, A.-M. and Toukin, C. (1998) Timber in Context - A Guide to Sustainable Use, NATSPEC 3 Guide.

Homeowners Guide To Landscaping

Homeowners Guide To Landscaping

How would you like to save a ton of money and increase the value of your home by as much as thirty percent! If your homes landscape is designed properly it will be a source of enjoyment for your entire family, it will enhance your community and add to the resale value of your property. Landscape design involves much more than placing trees, shrubs and other plants on the property. It is an art which deals with conscious arrangement or organization of outdoor space for human satisfaction and enjoyment.

Get My Free Ebook


Post a comment