Facing the challenge of designing an earth covered library to be built into the side of a hill in the Macedon Ranges, Victorian architect Paul Haar knew he’d need some exceptional materials to achieve his ambitious vision.
The school was situated on southeast sloping land in a small forest clearing with only one plot free for a new building.
Keen to preserve the view into the valley below from the school dining hub above this free plot, Paul recommended that the new library be built into the side of the hill with an earth covered roof. As such it could also be effective as a wildfire refuge in this bushfire prone area.
The resulting library sits on a concrete slab that lies 4.5m below natural ground at its northern edge and meets natural ground levels at its southern edge while the roof structure supports approximately 500-600mm of earth laid over the top.
In order to meet the engineering challenge, Paul proposed massive post and beam portals that carpenters could manufacture offsite in seasoned pine laminated veneer lumber (LVL) sustainably sourced from plantations of Maritime Pine (Pinus pinaster) grown in Western Australia.
As a result, 12m long x 1.2m wide x 35 and 45mm thick slabs of LVL (the stock from which LVL beams are normally cut to size) were specially intercepted from the LVL production line at Wesbeam in Neerabup Western Australia. They were delivered by train to Melbourne and by truck to the builder’s shed in Gisborne, ready for fabrication.
Paul was pleased that the LVL used for portals and purlin roof framing was able to address what was a massive structural challenge with some elegance.
“LVL timbers can do this and much more in a context where many would think they shouldn't – in a building that also provides effective wildfire shelter,” he added.
“Large billets of LVL were profiled and vertically screw-laminated into massive portal frames exposed internally to form a visually dramatic and gently warped roof structure that fans out like an opening book to the view below.
“Together with LVL purlins (ripped from portal billet off-cuts), a Radiata Pine plywood roof substrate and some good waterproofing, this timber roof structure supports 500-600mm of earth, grass, a tractor-mower and students at play.”
The stunning building was recognised at the 2012 Australian Timber Design Awards winning six awards including top honour, the 2012 Australian Timber Design Award. It also won the Engineered Timber Products Award, Best Public or Commercial Building, the People’s Choice Award and the 2012 honour on the Geoffrey Sanderson Perpetual Trophy.
The judging panel said it was greatly impressed by the expert use of engineered timber within the Candlebark building structure, particularly the broad-span timber roof designed to overcome the significant engineering challenge of supporting the layer of earth above it.
“The design is remarkable also for its careful detailing and timber selection,” they added.
Undeterred by advice from the structural engineer that such roof loads should be carried by concrete or steel structures, Paul held onto his dream of an all-timber roof frame, chosen for the carbon dioxide captured in it from the atmosphere, its easy workability, cost effectiveness and potential aesthetics.
“Sustainably sourced timbers used throughout the project have engaged the hands and hearts of a school community living in harmony with its forest surrounds,” he said.
“Complemented by blonde plywoods and salvaged and recycled woods, engineered timber products including Wesbeam LVL (e-beam + [F17]) elicit a warm but powerful architectural expression – a dance amongst the rustic and the refined – a place of strength and solidity that opens to a bright future.”