Faster, greener, neater and more accurate building with CLT - Eight-storey Bridport House completed in London
The unique residential building Bridport House represents green urban architecture of the future. It marks the first time that cross-laminated timber (CLT) has been chosen in the UK for an entire multi-storey structure, including the ground floor, which is traditionally constructed from concrete. Commissioned by the London Borough of Hackney and designed by Karakusevic Carson Architects, Bridport House offers altogether 41 maisonettes and apartments. It is considered one of the tallest residential timber structures in the world. The groundbreaking building with its innovative design replaces an old block of flats built in the 1950s.
Building type: Multi-storey residential building with 41 units
Location: Bridport Place, Hackney, London
Owner: London Borough of Hackney
Architect: Karakusevic Carson Architects
Main Contractor: Willmott Dixon ltd
Wood construction and assembly: EURBAN ltd
Quantity of CLT: 1,100 CLT boards, about 1,576 m³, 30 deliveries
Construction time: 12 weeks, from October to November 2010
London Borough of Hackney: “Using environmental materials we were able to meet the sustainability objectives and in the end real construction costs remained under budget.”
Great environmental advantage
The environmental advantage of using timber as a main construction material is that it stores carbon dioxide from the atmosphere as the wood grows. Construction with timber is the most sustainable way of building. It significantly reduces the global amount of CO₂.
According to the calculations for Bridport House, each apartment contains 30-40 m³ of timber, which is equivalent to more than 30 tonnes of CO₂. In addition, the wood used by Stora Enso Wood Products always comes from sustainable sources. It is PEFC certified, which is one of the two main internationally recognised certification schemes.
Karakusevic Carson Architects:
“CLT offers total freedom to design architecture that will stand the test of time. Our goal was to create architecture that is both high quality, expressive, robust, simple and of a durable and lasting nature.” Learn more about Karakusevic Carson Architects.
Freedom of design
The wood-framed Bridport House, located in Hackney, London, is orientated east-west, with all apartments benefiting from morning or evening sun. Family units with private entrances are located on the ground floor. The upper floors provide a range of 1-3 bedroom apartments. All apartments are well lit with natural daylight thanks to large windows.
Generous balconies with excellent daylight are provided in all 33 apartments located on the upper floors. All of the ground-floor family apartments have private patio gardens. The key objective of the design team was to achieve a practical and economical layout using the flexible CLT building system, which presents no limitations to the architecture, design or style of a building. CLT boards were prefabricated according to the architect’s designs.
In Bridport House, solid timber is successfully combined with other building materials such as brick, aluminium and copper, which were used in the architectural details.
Willmott Dixon, Terry Waite, Site Manager:
“I love building with CLT. It’s fast and simple to use, as well as clean and precise. Because CLT is factory-made and delivered to the site for assembly, there is far less waste than in conventional construction. The workers on the site also enjoyed working with prefabricated timber as opposed to steel or concrete. It is a nicer and cleaner material to work with.” Learn more about Willmott Dixon.
Safe and long-lasting structure
The main contractor, Willmott Dixon, consider CLT an ideal solution to the very specific issue of weight. “The large Victorian sewer running beneath the site of Bridport House made it unsuitable for a traditional and heavy concrete frame structure,” explains Terry Waite, Site Manager, Willmott Dixon.
Waite also highlights that cross-laminated timber from Stora Enso offers many additional advantages apart from its light weight, air-tightness, acoustics and minimal assembly time. Because of CLT’s dimensional stability, the material was also used to form the lift shaft instead of steel or concrete. Safeness and fire performance are additional benefits. The frame structure is long-lasting and would be suitable also for earthquake zones due to its strength. The massive wood creates a healthy indoor climate since solid wood regulates room air humidity to the optimal level for health. “Cross-laminated timber is a massive timber material that does not bear extra risk in the case of fire. The outer parts would char, protecting the bulk of the material and bringing no danger of structural collapse,” Waite comments.
Wood Engineering and Construction:
Timber engineer and contractor, EURBAN, engineer Philip Zumbrunnen:
“CLT is considerably lighter than the alternative structural materials. With CLT you have line loads, not point loads. Thanks to CLT, the height of the structure was doubled compared to the previous building, while the weight increased by only 10 per cent.” Learn more about EURBAN.
Only 12 weeks’ assembly
The short, only 12 weeks’ assembly time on the site was possible due to the prefabricated CLT boards, which are simple and accurate to put together. EURBAN estimates that the assembly time is half that of conventional reinforced concrete. According to EURBAN’s professionals, CLT is an attractive and competitive alternative to concrete or steel. Even 10+ storeys are possible with the flexible material. When building with timber, the process is less likely to be interrupted in bad weather conditions, such as temperatures below zero. Because construction was faster, the disruption the site caused to the neighbours was also reduced. Watch a video of the construction process!
Stora Enso Wood Products, Matti Mikkola, SVP, Building Solutions:
“Bridport House is excellent proof that urban multi-storey construction can be done both cost-competitively and sustainably using CLT as a green building system. If the majority of European homes were to be built of wood instead of concrete, the environmental load caused by housing construction would reduce substantially.”
Bridport House in BBC News
Wooden buildings reach new heights. Bridport House is built of wood, and it is the largest timber-built apartment block in the world. See the video!
Green homes: What about wood? Nick Higham reports on why Britain has started to build blocks of flats out of timber. Listen!
Stora Enso CLT facts
Cross-laminated timber (CLT) is a strong and dimensionally stable material built up with layers of wood, almost always spruce, in which the timber in each layer is orientated in the opposite direction of the material below. Using odd numbers of layers, CLT is manufactured in different thicknesses. At Bridport House, the CLT in the walls vary from three layers (95mm) to five (160mm) or seven layers (220mm). Stora Enso Wood Products’ CLT is produced at the company’s purpose-built factory in Austria using locally sourced PEFC-certified spruce. It differs from other brands of CLT because it requires only a minimum of three layers to achieve air-tightness, not five or seven, as is often the case. It is also edge-glued to make it even more stable and airtight.
Stora Enso facts
Stora Enso Wood Products is Europe’s leading wood products manufacturer and part of the Stora Enso Group, providing a wide portfolio of wood-based products and solutions for building, decorative and packaging uses. The Building Solutions unit of Stora Enso Wood Products aims to be the leading company in sustainable construction solutions in Europe. This is the first high-rise built with our CLT – do you want to build the second, third or the fourth?