Above left: Using MiTek Pamir software alongside AutoCAD, Crendon’s design team developed a comprehensive 3D model Above right: Solid timber ceiling joists created the ceiling structure
Crendon’s comprehensive package included the supply and installation of wallplates and straps, trusses, posi-rafters, infill timbers, valley gutters, firrings, ply decking, and associated metalwork. The end result was a fully integrated structure designed for accuracy, performance, and ease of installation.
DESIGN INNOVATION AND TECHNICAL CHALLENGES
The complexity of the roof design presented several technical challenges, particularly around accommodating the vapour control membrane that ran internally throughout the building. Although this was outside Crendon’s direct scope, the design team incorporated the detail into their drawings to ensure it was correctly co-ordinated on site. With independent ceiling joists and posi-rafters rather than a prefabricated truss system, the structure also required additional consideration for wind uplift and restraint. Mr Underwood and his team devised a robust solution using framing anchors, inverted truss clips, and through-plate fixings to provide full structural stability.
Due to varying wallplate levels across the roof zones, detailed plate-level drawings were produced to ensure each section could be accurately installed. At the ridge level, the posi-rafters were extended vertically to meet the underside of the steel, allowing for a fully nailed hanger connection into timber packing within the steel web, a detail that demonstrated the team’s precision and attention to buildability.
COMMITMENT TO SAFETY
Health and safety were central to Crendon’s approach. The company placed emphasis on maximising off-site manufacture to minimise manual handling and cutting on-site.
Solid timber joists were OSB-clad before installation of the posi-rafters, creating a secure working platform above. Within the ceiling area, service voids were capped during installation to prevent falls. Pre-cut noggins and firrings further reduced the need for on-site cutting, helping to minimise dust and improve efficiency.
Crendon’s contracts manager prepared the RAMS documentation and carried out regular site inspections to ensure a safe working environment. His management of the site programme and material deliveries ensured progress remained consistent while maintaining clear, hazard-free workspaces.
A SUSTAINABLE APPROACH Sustainability was an integral part of Crendon’s design philosophy.
The company prioritised simplicity and efficiency, producing a design that reduced waste, optimised material use and minimised site emissions.
By maximising the use of engineered timber products such as posi-rafters and trusses, the design reduced the reliance on heavier, more carbon-intensive materials. Although ridge steelwork had already been specified before Crendon’s involvement, the design team continues to explore timber alternatives wherever feasible.
All timber supplied was covered by PEFC Chain of Custody certification, ensuring it originated from responsibly managed forests. Beyond individual projects, Crendon continues to invest in sustainable operations, installing solar PV panels, EV charging infrastructure, and electric forklifts across its manufacturing sites.
COLLABORATION AND LEARNING The success of the project was underpinned by early collaboration between Crendon Timber Engineering, Kier Construction, and the wider design team.
Jamie Underwood, who has worked in timber engineering since 2005, led the technical delivery and brought extensive experience from both commercial and residential projects.
Regular design meetings ensured potential issues were resolved early, avoiding costly delays. Using MiTek Pamir software alongside AutoCAD, Crendon’s design team developed a comprehensive 3D model that supported clear co-ordination between disciplines and ensured a seamless transition from design to manufacture.
The project also highlighted the importance of flexibility and adaptability. Late design
amendments were handled efficiently through clear communication between Crendon’s office-based designers and on-site teams.
RECOGNITION OF EXCELLENCE The TRA Roofscape Design Awards judges praised Mr Underwood’s design for its technical proficiency, attention to detail, and strong collaborative ethos. The LDA Unit project exemplified best practice in roof design and installation, meeting the twin demands of structural complexity and healthcare sector safety.
“This is a strong example of engineered timber performing well in a complex healthcare setting,” said Nick Boulton, chief executive of the Trussed Rafter Association. “The roof design supported sequencing requirements and integrated cleanly with structural steel and services.
“What stands out is the focus on safety, repeatability and co-ordination. These are the kind of projects that demonstrate the versatility of structural timber, particularly when design and manufacturing are aligned early.
“The Roofscape Design Awards are designed to highlight precisely this kind of work, where structural expertise meets real- world delivery.”
“The project required high levels of accuracy, particularly around sequencing and interface points,” added Mr Underwood. “The focus was on delivering a safe, efficient and robust solution that could be installed with minimal rework. It was a technically challenging scheme and the outcome reflects co-ordinated input from all parties.” The company’s win at the TRA Awards follows a series of recent successes, including being named Structural Timber Systems Supplier of the Year at the TTJ Awards in September, further recognition of Crendon’s ongoing commitment to quality, sustainability and innovation in engineered timber design (see pp20-25).
Through thoughtful planning and expert
execution, Crendon Timber Engineering delivered a challenging roofscape that now stands as a model of excellence within the trussed rafter industry. ■
www.ttjonline.com | November/December 2025 | TTJ
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