The value of trussed rafters

Trussed rafters offer a significant opportunity for hospitals and healthcare facilities to complete complex builds on time and in budget. A recent project in Dawlish, Devon, offers a perfect example.   

Hospitals demand the highest standards in design and delivery. At Langdon Hospital in Dawlish, a £15 million learning disability and autism (LDA) unit has recently been completed to provide specialist care in a modern, therapeutic environment. The roof structure was a particularly complex element of the build, highlighting why working with Trussed Rafter Association (TRA) members gives clients and specifiers confidence. 

The new unit measures 49m x 59m and incorporates four pitched roofs linked by interconnecting structures. Meeting this brief required a combination of trussed rafters, posi-rafters, raised tie trusses, solid timber joists and flat roof sections, all integrating with ridge steel beams and glulam valley beams. 

TRA member Crendon Timber Engineering was appointed by Kier Construction to design, supply and install the full roof package. Jamie Underwood, Senior Designer at Crendon, produced detailed drawings to ensure accuracy and prevent errors on-site. The team also had to account for a vapour control membrane running continuously across the building, as well as wind-uplift restraint where joists and rafters acted independently rather than as prefabricated trusses. 

Integrated supply and fix 

Crendon’s scope covered wall plates, straps, trusses, rafters, infill timbers, valley gutters and flat roof materials. By managing the complete roofing bundle, the company provided clarity and consistency across all elements. At the ridge level, posi-rafters were engineered with extended verticals to connect securely into the steel beams, ensuring robust fixing. 

Working at height poses risks on every project. TRA members are committed to designing systems that simplify installation and make sites safer. At Langdon Hospital, ceiling joists were OSB-clad to create safe working platforms, while service voids were capped to prevent falls. Pre-cut noggins and firrings were supplied to reduce on-site cutting and dust, improving both safety and efficiency. 

Sustainability in action 

Engineered timber is one of the most sustainable structural products available. For this project, trussed rafters and associated timber elements were chosen wherever possible to reduce reliance on steel. Off-site preparation minimised waste, and all timber supplied carried PEFC Chain of Custody certification. 

Nick Boulton, Chief Executive of the TRA, said: “Trussed rafters remain the most widely used roof solution in UK housebuilding because they combine strength, versatility and cost efficiency with sustainability. This project shows how TRA members bring the same trusted benefits to complex commercial builds.” 

Lessons for housebuilders 

Although this was a healthcare scheme, the principles are also directly relevant to housing. Trussed rafters offer speed of installation, flexibility in design, and just-in-time delivery that reduces site storage requirements. These are the same advantages that help housebuilders control programmes, reduce risks and achieve quality outcomes at scale. 

Reflecting on the project, Jamie said: “This was a technically demanding roof, but by applying TRA standards and working closely with Kier and our installation partners, we delivered a solution that was simple to install, safe for operatives, and sustainable. It’s a great example of how TRA members work together.” 

The Langdon Hospital roof was completed on programme in October 2024. It demonstrates how TRA members combine technical capability, design innovation and practical delivery to support clients on every kind of project. For specifiers and housebuilders alike, the message is clear: when trussed rafters are supplied and installed by TRA members, the result is a structure that is robust, efficient and sustainable. 

The Roofscape Design Awards celebrate excellence in timber trussed rafter roof design. The awards recognise projects that demonstrate innovation, sustainability, and high design standards.  

www.tra.org.uk