The Green Oak Carpentry Company collaborated with TSH during the technical design phase to contribute to the Glulam Frame’s design and specifications. Nigel Challis from AWA was enlisted for structural design expertise. Overcoming the challenge of achieving portal action, slender 315 x 120mm oak glulam beams were utilized, concealing any steelwork within the section.
Innovative joint design, known as the ‘Corbett Knuckle,’ involved machining large steel billets into timber recesses with threaded bolts, plate washers, and nuts, ensuring a tight connection. Precision in the German factory’s production, where oak glulam beams were manufactured and CNC-cut, was maintained by meticulous data files from draftsman Mike Shally.
Assembly, assisted by ‘Cherry Pickers’ and a site crane, showcased the use of tapered dovetail joints for seamless component integration. Oak glulam sections featured finger joints for defect grading, earning a cautious D30 structural grade, though realistically attributed D40 by engineer Nigel. Despite a thin application of clear oil in the factory, the assembly coincided with a wet spring causing oak tannins to run, but a pre-applied sealer facilitated easy cleaning.
The final structure, despite potential concerns about the roof light’s relationship to the frame grid, exuded a sumptuous quality, serving as a beautiful and valuable addition to the school.