Main ContractorMorgan Sindall
ArchitectCorstorphine & Wright
Structural EngineerCurtins Consulting
B&K Structures designed, supplied, and installed a hybrid timber and steel structural system for Extra MSA Group's Skelton Lake Services, located just outside of Leeds.

The client, Extra MSA Group, commissioned the project in a bid to provide a world-class service station to passing travellers in a tranquil backdrop that didn't negatively impact the bird sanctuary and instead integrated itself within RSPB Skelton Lake. The service station is an exemplar of hybrid timber and steel construction, showcasing the biophilic and sustainability properties of the timber materials in collaboration with the structural benefits of steel.

The brief for Skelton Lake Services was to deliver an entirely new concept of service stations that places a focus on the wellbeing of the end-user through a diverse range of services and facilities and the biophilic benefits of engineered timber. Extra MSA Group required a striking and ambitious structure that integrates with the surrounding area of the service station, creating a relaxing and tranquil space for visitors.

Skelton Lake is a stunning example of embracing a location aesthetic and the possibilities of using mass timber in conjunction with steel frames for a hybrid structure. The building benefits from striking architecture that is visible against the beautiful backdrop of the nature sanctury. This is an incredibly effective look that breaks the trend of traditionall service station aesthetics.

B&K Structures delivered an exposed glulam frame for the roof to achieve the required unique aesthetic and paired it with a steel structure for the retail and back of house ancillary spaces, to suit the client's value expectations and requirement for flexible spaces.

The curved cassettes used on the roof of the building required technical development to determine buildability through a trial erection in Austria, which streamlined the installation process on-site due to the complexity of the build A series of 12 undulating roof ribbons, each with their own unique geometry, are combined to form the structure's curvilinear roof to create a stunning external feature piece.

The varying requirements of Skelton Lake required the use of the appropriate structural solutions in order to meet the brief, which in this case was hybrid glulam and steel. It was imperative that the onsite performance of Skelton Lake met the design expectations, therefore detailed research was undertaken on the physics of the building which positively impacted the outcome. From a build point of view, the hybrid structure performed much better than either a solo steel or timber construction, as it allowed for much of the differential movement between the timber and steelwork.

The exposed structure and ireggular pattern of intersections between eaach roof ribbon used on Skelton Lake cretes a striking form to the underside of the ceiling over the double-height atrium, allowing for the addition of glazing at a high level where the adjacent ribbons cross one another. In total, B&K Structures installed 142 glulam beams with a total of 1,793 lifts of timber cassettes, glulam, and structural steelwork components. Split across three phases, the construction was completed in approximately 18 weeks. Strong collaboration between BKS and Rubner ensured that each roof cassette was designed to follow the glulam's complelx geometry to form the flowing design of the roof structure.


Corstorphine & Wright investigated the use of glulam for the whole building; however, a hybrid structure of timber and steel was found to be more suitable. Steel was more appropriate for the cellular nature of retail and back of hour ancillary spaces, whereas for the main seating and dining areas, the exposed glulam frame achieved the long, open spans and decor required for public and visible areas, as well as forming a strong link to the landscape with the external curved glulam beams.

Using a Computer-Aided Engineering approach, B&K Structures was abkle to extract data to produce a robust design strategy. The use of a combination of bespoke brakcets and Megant Connectors reveals no visual clues internally, meaning that visitors can fully appreciate the impression of movement given by the continuous undulating beams.

Versatile roofing cassettes can be adapted to meet various physical and loadbearing requirements, and for Skelton Lake the timber cassettes were tailored to accommodate the loading demands of the undulating green roof. The structure consists of loadbearing timber ribs, and clad top and bottom with mineral wool thermal insulation. A moisture-adaptive vapour barrier was applied seamlessly across the full width of the cassette, ensuring the desired performance of the building can be met. For motorway service stations, noise levels present a real issue due to the close proximity of the road to the building - this is where the timber cassettes come into their own, as they are designed to resist sounds travelling into the space.


The prefabricated and pre-assembled timber roof cassettes were delivered to the site as one through wall build-up to maximise the offsite advantages including a reduced number of material deliveries, reduced social impact due to fewer onsite personnel and a dramatically reduced installation time, while also minimising the amount of waste generated by the construction. The key to the successful delivery of this project was the excellent collaboration across all disciplines of the design team at B&K Structures and Corstorphine & Wright who worked together closely to ensure a strong architectural concept that was driven through the technical delivery phases of offsite manufacture and onsite delivery. 


Substantial research was conducted on the building physics of Skelton Lake to ensure that the sustainability performance met the design expectations. The use of sustainable glulam beams and timber cassettes proved to be key in reducing the environmental impact and went on to mitigate the 'in use' impact by achieving a highly energy-efficient and airtight structure.

Throughout the design stages, Corstorphine & Wright audited sustainability measures against their in-house sustainability criteria and, as standard, waste strategies were implemetned, and sustainable materials were sourced. All timber supplied by B&K Structures is sourced from well managed and legally compliant sources, and to assure the responsible sourcing verification of the timber, the company gained FSC and PEFC Chain of Custody Certification, which ensures that any cultivated timber is replanted, thus protecting the local ecology and assuring that forest workers are treated fairly.

The CLT and glulam used in the project will store carbon for the lifetime of the building and, should it be recycled correctly, beyond this time. Additionally, the creation of a green roof planter with wildflower turf and local plant species adds to the biodiversity of the area, and tree planting along the borders links the site with existing tree cover.

Skelton Lake is a major local employer, providing up to 300 new jobs to the area, which will prove to be incredibly important as land to the east is due for the development of 2,000 new homes. The structure received a 'Very Good' BREEAM which is awarded based on a wide range of sustainable values including but not limited to innovation, land use, materials, energy, and waste.

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