The client required six levels of apartments in addition to car parking to be constructed on the inner-city site.
Height constraints and a contractor familiar with lightweight construction led to a timber-framed option being developed. A reinforced concrete car park was formed on the ground level, with a six-level timber-framed superstructure sitting above. Most apartments are studios, with relatively small proportions, meaning bracing lines were available at 4 m centres in each direction. This led to a concept based upon plywood-braced walls. Grade F8 timber studs are used, being 140 mm x 45 mm on the lower two levels and 90 mm x 45 mm on the upper levels. Plywood is nail fixed over these, with thicknesses of 19 mm on the lower two levels, 15 mm on the central two levels and 12 mm on the top levels. Floors consist of 19 mm plywood fixed over timber I-section joists. Additional to the ply bracing, three steel k-braces were used to provide torsional restraint to the structure while also accommodating window penetrations. This apartment block demonstrates that multi-storey buildings can be built successfully from timber.
This article, Six-Level Timber Apartment Building in a High Seismic Zone gives more information.
Wellington, New Zealand
Holmes Consulting Group
New Zealand Timber Design Journal, 2005, Issue 2, Vol 13, pp 11–15