AA Design + Make Masters study at the Architectural Association Hooke Park

Project: Big Shed 2010-12

Above: Sharing stories about architecture: Hooke Park, a film by Safwat + Williams.

The Big Shed is D+M students’ first building. It was designed in 2011 by the first intake working with students of AA Diploma Unit 19. The building is a 500m2 assembly workshop that accommodates fabrication, assembly and prototyping activities at Hooke Park. Since spring 2012, the building is the primary workspace of Design + Make, providing a sheltered site for the production of the programme’s future built output.

The building is constructed from larch, sourced from Hooke Park and local woodlands. For the primary structure, tree-trunks are be used “in-the-round”, thereby retaining their full structural integrity.

Big Shed project student blog here.

Project Credits

Students: Nozomi Nakabayashi (Design & Make); Elena Gaider, Eyal Shaviv, Olivia Putihrai, Samuel Nelson, Sanem Alper (Diploma Unit 19)

Teaching Team: Martin Self (Program Director); Piers Taylor, Kate Darby (Studio Tutors); Charley Brentnall (Make Tutor)

Executive Architect: Mitchell Taylor Workshop (Piers Taylor, Luke Holcombe)

Structural Engineer: Atelier One (Aran Chadwick, Luis Fernandez, Elizabeth Bismut, Eva MacNamara)

Civil Enginner: Buro Happold (Bob Riley, Joseph Walton)

Timber Testing: Bath University (Prof Richard Harris, Nick Gathercole)

Contractor: Charley Brentnall

The building structure, engineered by consultants Atelier One, has pioneered the use of high-capacity screwed connections within large round-wood trusses. Developed through an experimental testing collaboration with Bath University, this approach allows trees to be used in-the-round in complex structures without the need for major engineering processing. It demonstrates an approach to building that maximises the use of local resources and minimises reliance on industrial production of building components.

Un-regularised larch roundwood was used for the primary structure. Larch was chosen for its good durability and current availability due to recent surgical felling to prevent the spread of phytophthra in South West England. The wall panels are clad using western red cedar planking (typically 30mm thick and 100mm wide), sawn from about 30 trees felled at Hooke Park. The planks are carried on triangular “cassettes” with a sawn larch substructure.

The fabrication of the trusses was carried out by a team which consisted of students both from Design + Make and summer volunteers on the AA’s SummerBuild programme at Hooke Park, who worked alongside experienced timber framers led by Charley Brentnall. Each of the planar trusses was fabricated and assembled horizontally, before all being lifted into position on the building’s concrete slab. Similarly, the cladding cassettes were assembled flat and then lifted into place.

The majority of the truss connections use sets of Heco Topix screws, up to 400mm long, at cross-angles through each joint. The angle of each screw had to be defined in a way that correctly related to the force direction and the timber grain (the screws need to be oblique to the radial axis of the tree to prevent splitting).

Another complexity was in how to best match the naturally varying trees trunk to the differing structural performance requirements within the structure. By mapping the engineer’s analysis-derived forces onto the structure, the natural variations in diameter, taper, straightness and quality (measured by the number and size of knots) were taken into account so that each tree is optimally used in the building.