B&K Structures are one of the UK’s leading sustainable frame contractors, specialising in the design and delivery of engineered timber and timber-steel hybrids. 2024 marks their 50th anniversary, having begun their journey in 1974 specialising in steel fabrication before adding engineered timber to their portfolio in 2007.
Since then, the Derby-based business have become experts in timber and timber-steel hybrids, carrying out numerous innovative and award-winning CLT, glulam, steel and hybrid projects across the UK. Their roots in steel have enabled then to become one of the UK’s largest timber-steel contractors, now split into two distinct entities: B&K Structures (BKS) and B&K Hybrid Solutions (BKHS).
The curving roof beams at Skelton Lake Services. Images courtesy of B&K Structures.
“We have extensive specialist experience with designing and constructing both engieered timber projects and structural steelwork projects. However, hybrids – integrating both materials – now account for a significant proportion of our work,” explains Alex Brock, Pre-Construction Manager. “We are seeing an increasing demand for timber-steel hybrids combining the benefits of, and our significant experience with, both solutions.”
Since 2007, BKS and BKHS have delivered over 500 engineered timber, steel and timber-steel hybrids in the UK, operating across all major sectors including commercial, industrial, education, leisure and retail. They now have a team of over 150 staff – including Structural Engineers, Draughtsmen, Project Managers, and a dedicated Sustainability team – and in 2021 they acquired a state-of the-art steel manufacturing facility. This significant investment has not only doubled turnover but guarantees in-house supply for their steelwork and hybrid projects, allowing them to take on larger and more complex schemes, up to and above £10m.
Re-envisioning retail
While commercial, industrial and education are now their primary sectors, it was retail that was the first major sector to embrace engineered timber.
“These were typically glulam and engineered timber structures to the front of house and structural steelwork frames to the back,” Alex explains. “Drawing on our experience with structural steelwork, these were the first ‘hybrids’ we constructed and have paved the way for some of the large-scale projects we are seeing today.”
M&S Cheshire Oaks exemplifies B&K Structure’s innovative supermarket designs
M&S Cheshire Oaks is an excellent example of this; one of the largest stores built by the retailer comprising 148,000sq feet of retail space with prominent curved glulam beams to the roof. The store’s roof is supported by 48 structural steel tree arms, and, with the incorporation of timber, it is 20% lighter than a steel equivalent. An iconic retail project, it has laid the foundations for more recent hybrids in this sector.
Skelton Lake Services
Skelton Lake Services is another notable project – this time bringing a hybrid timber-steel solution to a motorway service station. The client wanted a unique design which would blend seamlessly into the landscape, and BKS were appointed to design, supply and install an ambitious curved roof formed from CLT and glulam beams. A series of 12 undulating roof ribbons, each with their own unique geometry, are combined to form the curvilinear roof.
The timber structure is paired with a steel frame for the retail and back-of-house ancillary spaces, and a combination of bespoke brackets and Megant Connectors keep the exposed timber’s look undisturbed so that visitors can fully appreciate the impression of movement given by the continuous beams.
6 Orsman Road, designed by Waugh Thistleton architects combines CLT and steel to provide 34,000 sq. feet of office space
The commercial sector
Many TDUK members have noted the increased appetite for timber within the commercial sector over the past few years, and BKS are no exception. “This is due in part to increasing demand from clients for sustainable, aesthetically pleasing workspaces which prioritise occupier’s health and wellbeing” says Alex.
“Tenants and end users are becoming increasingly conscious of their own carbon credentials and timber is quickly becoming the accepted solution.”
High-profile commercial projects are helping to reshape this landscape, and Orsman Road was a landmark project in this respect. Backing onto London’s Regent’s Canal, the building’s core walls, stairs and floors are CLT, in combination with cellular steel beams and steel columns, to provide 34,000 sq. feet of office space. The use of a hybrid timber-steel solution enabled a lighter building to be constructed within a reduced time scale, with smaller foundations and fewer deliveries to site.
“It was one of the first high-profile commercial offices to specify exposed timber soffits,” Alex points out. “CLT is showcased throughout the building – in the staircases, in the walls. It is still, in many ways, the model building for hybrid timber offices.”
CLT runs throughout Orsman Road’s interior: exposed on the walls and providing staircases too.
More recently, timber-steel hybrids have been a favoured solution in commercial redevelopments, where timber’s lightweight strength presents an advantage. BKS recently delivered both the Gramophone Works and the Technique building – which fall into the “extension/retrofit/refurb” category – utilising timber to economically add additional storeys, increasing tenant capacity without the need for significant strengthening of the existing superstructure.
“From a commercial perspective, timber-steel hybrids can help to reduce cost and maximise building and material efficiency, often allowing timber to be considered in the place of other materials,” Alex says. “With the UK’s commitment to Net Zero by 2050 fast approaching, we believe hybrid solutions and engineered timber structures are the construction industry’s only answer to the climate crisis.”
Berkeley Square: London’s tallest mass timber office building
Increasingly, the scale and complexity of these commercial timber and hybrid timber-steel buildings is growing.
BKS and BKHS are currently on site with several large-scale projects, including Paradise SE11, the Metropolis Building and 36-38 Berkeley Square. The latter is due to complete this year and is a nine-storey exposed CLT office block. Key to the realization of Berkeley Square’s ambitious design was a shared commitment to timber across the team and early engagement.
]“There was no wavering, or talk of using any other materials,” Alex says. “A great deal of hard work went into demonstrating the compliance of engineered timber within the current guidance. Early engagement between all parties was crucial – particularly with specialist timber subcontractors like ourselves, who have vast experience of overcoming the challenges associated with the design and delivery of timber and hybrid timber-steel structures, and can offer early guidance,” says Alex.
Image showing proposed design for 36-38 Berkeley Square. Image courtesy of Piercy&Company Architects.
By having a design team and project team that understands timber and how to design with it, any risks can be mitigated and designed out at an early stage, increasing the speed and ease of construction.
“We are really pushing clients that aspire to build with timber to engage with us pre-construction to help mitigate those risks.”
The team’s hard work has paid off: Berkeley Square has already found a prestigious tenant – Chanel – who have secured the whole building for the next 20 years, despite it still being on site.
Education and leisure
While momentum is now increasing in the commercial sector, the education sector has long advocated for timber.
The past few years have seen some great examples of engineered timber schools and universities, and CLT and timber-steel hybrids can be excellent solutions.
BKS and BKHS have contributed to numerous education projects. One recent project of note is Fife College, a new state-of-the-art learning campus designed as a Net Zero Carbon Pathfinder. Using a hybrid CLT, structural steelwork and Deltabeam solution, Fife College aims to be the first net zero tertiary education building in Scotland, saving 25% of the embodied carbon usually anticipated in a structure of this scale.
It’s currently the largest Deltabeam and CLT hybrid project in the UK. The team designed and delivered almost 9,000m2 of CLT and over 1,400 tonnes of structural steelwork to create a sustainable campus for over 4,500 students and faculty.
“Engaged early under a PCSA, we developed the Deltabeam and CLT solution alongside the project team,” Alex reveals.
Another example is Trent View College in Scunthorpe, a DfE Passivhaus school where structural steel was used internally for the columns and beams, with CLT used as the external wall system. Sealing the joints and details to reach the airtightness standards required to achieve Passivhaus, Trent View is now one of the most energy-efficient education facilities in the UK
The leisure sector is another mainstay of BKS and BKHS’ work. Spelthorne Leisure Centre uses a similar structural concept to Trent View College: a load- bearing CLT external wall, with a steel exoskeleton, with structural steelwork and glulam internally. Located in Staines-upon-Thames, it will be the UK’s largest ‘wet and dry’ Passivhaus leisure facility, housing a 25m pool, sports hall, studios and a sports pitch on the roof. Spelthorne Borough Council expect the new building to use 60% less energy than a typical modern leisure centre.
Trent View College: the CLT exterior houses the steel frame within. Image © HLM Architects.
The right materials for the right project
“We have now delivered well over 500 engineered timber, steel and timber-steel hybrids,” Alex states. “We’re seeing timber’s potential in the commercial sector develop, and the scale of these projects is substantially larger in recent years.”
“I think this is a direct result of the confidence in building with timber at scale. However, in this sector, the interaction between timber and steelwork is currently the biggest mover.”
He points out that, while full-timber solutions unquestionably have lower embodied carbon emissions, a timber-steel hybrid is often the most efficient and commercially viable way – sometimes the only way – of introducing timber into a project. “Large full-timber schemes are trending upwards in the UK market, despite facing some financial and insurance challenges,” Alex says. “While this is improving, it can still introduce some trepidation for clients.”
“Developers often compare traditional methods of construction versus full engineered timber, and if they can’t quantify the benefits, they may revert to traditional building methods. This is where timber-steel hybrids can be an inroad for timber and our ability to now supply steel in-house is an advantage. Having the right combination of materials in the right place is the best way to ensure timber gets used.”
This article appears in Designing Timber issue 7.
Thanks to Alex Brock and Bethan Roper of B&K Structures.
