Kangaroo Point QLD
The use of engineered timber was the key driver behind the development.
The site sits directly over the top of the M7 Clem Jones Tunnel, one of Brisbane’s road tunnels linking the south to the north under the Brisbane River.
Monterey uses a hybrid structural system, made up of multiple structural materials. The foundational basement structure is made of concrete, taking the load of the floors above. Concrete columns and beams then support a concrete transfer slab on the ground floor, which creates a sturdy base for the remaining mass timber apartment levels. CLT walls, glue laminated timber beams and CLT floor plates make up the mass timber floors.
Timber was chosen as the superstructure for multiple reasons, including:
- Speed of construction
- Site constraints
The initial, and most important reason timber was chosen, was due to its lighter weight than concrete. The project sits above an underground freeway tunnel, which meant the building had significant weight constraints in order to not impede on the structure below ground.
Aurecon, the engineers on the project, state the project was able to go from 5-6 stories to 10 stories due to the weight difference. This was ultimately what got the project over the line as financially viable. The engineers were able to model the pressure from the foundations against the pressure limits of the tunnel crest below.
An interesting factor that the engineers had to account for was axial shortening. Unlike concrete, timber changes moisture levels, so it can change length throughout time periods. Connections were detailed differently for different floors to ensure even axial shortening, which was essential to maintaining the integrity of the connection.
A concrete core houses the lift shaft for the building, and provides lateral bracing for the building. CLT buildings can have timber cores, but for this particular building, concrete became the best option. The structure is very long and narrow, which subjected it to high torsion loads, requiring the concrete core as a strong element to pin to.
XLAM, the suppliers of the CLT panels, notes that their manufacturing assembly line relies on automation, and limited handling by humans. This maintains a quality of timber, as it is moved around by vacuum lifts, avoiding bruising or denting that can arise from manual transport.
The project features a 1200m3 of CLT, and 83.5m3 of GLT, all of which locks in carbon dioxide, generating a positive impact on the environment.
Exposed CLT was used sparingly throughout the building, but a notable example is on the balcony soffits. The mass engineered timber superstructure becomes pronounced at night with external lighting enveloping the exposed timber in a warm glow.
The surrounding context of the site was mainly heritage Queenslanders. The use of mass engineered timber for the superstructure allowed the architects to align the datums with the timber framed heritage Queenslander homes in front.