Ground-Breaking Bridport House Built from PEFC Certified Spruce Wood

13 March 2012 Construction

London-based Bridport House is a ground-breaking multi-storey residential complex built from cross-laminated timber (CLT) sourced from PEFC-certified spruce forests of Central Europe.

Designed by Karakusevic Carson Architects and overseen by building contractors Willmott Dixon, Bridport House in the London Borough of Hackney is the first stage in plans to reinvigorate the Colville Estate, a 1950s housing project. Built from cross laminated timber, it is intended to replace an original 1950s building. Bridport House includes 41 new homes, housed in two adjoining buildings, respectively eight and five storeys high.

The cross laminated timber is made from PEFC certified spruce wood supplied by the company Stora Enso Wood Products and sourced from its purpose-built factory with fully integrated sawmill at Bad St Leonard in Austria.

Stora Enso Wood Products is a Scandinavian wood products and packaging company with head offices in Stockholm and Helsinki. The company is committed to environmental sustainability. In particular, it is committed to respecting all national forestry laws. It also supports local certification schemes which are independently audited by third party certification bodies, including PEFC. The raw material that went into the cross laminated timber (CLT) supplied for Bridport House was sourced from PEFC-certified central European forests.

The Bridport House project has pushed the boundaries of timber engineering. This particular project is the first time that CLT has been used in the UK for the construction of an entire multi-storey structure, including the ground floor. In the past, although the material has been used in multi-storey constructions, until now, the ground floor has tended to be constructed from concrete.

This particular project has clearly demonstrated the advantages of using CLT for buildings. CLT is lightweight (one of the key criteria for this project), it can be assembled very rapidly and above all, it has important carbon sequestration properties. The issue of weight was an important consideration in light of the fact that the site on which Bridport House is located has a storm relief sewer running northwest to southeast directly beneath it making it unsuitable for a traditional heavy concrete frame structure.

The structure has been designed so that the load-bearing CLT panels, which have line loads as opposed to point loads, are placed in a variety of positions on each floor, thereby spreading the load. This has also made it possible to double the size of the structure with an overall increase in the weight of only 10%.

In addition, construction of the structure took 10 weeks, making it considerably faster than the time required for a structure with a conventional concrete frame for which construction time is estimated at around 21 weeks.

Finally, in addition to the structure's PEFC credentials, the use of CLT also makes further environmental sense, thanks to its carbon sequestration properties. According to the contractors, Willmott Dixon's in-house sustainability consultancy, Re-Thinking, which has been working with Cambridge University's Centre for Sustainable Development, had the building been made using a conventional reinforced concrete frame, the materials required would have incurred an additional 892 tonnes of carbon. This is equivalent to 12 years of operational energy required to heat and light all the dwellings at Bridport House. When the sequestered carbon locked up in this 1,576m³ timber structure is added to the carbon avoided, the total figure is 2,113 tonnes of carbon: equivalent to 29 years of operational energy. Put another way, with 20% renewable energy, it would take 144 years to save the same amount of carbon.

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