Twi timber entryway Baptiste Marconnet Photography

Te Whare-iti: Dorking Road House


Richard Wright / Aonui Architecture

11. Innovative timber manufacturing & technology award

Photographed by: 
Baptiste Marconnet

The Dorking Road house in Wellington embodies the many benefits of Te Whare-iti modular timber design. Poor access discouraged attempts by the client to procure a small second dwelling on their unused back yard using traditional construction methods. The solution was an offsite-manufactured (OSM), crane-delivered, modular home with pinus radiata cross-laminated timber (CLT) as the primary structure.

The modular Te Whare-iti design is a response to the need for affordable architecturally designed homes to fit diverse buyer requirements even on challenging sites, including steep slopes without vehicle access. Utilising such sites allows densification of cities, promoting efficient use of infrastructure, and addressing the existential challenges of global warming.

The system comprises a set of standard modules that can be combined into plans of any size and shape. The advantage of having pre-designed modules is that the cost of designing each new house is kept to a minimum.

CLT makes up the floor, walls, and roof, with neoprene gaskets creating airtight panel joints. Computer numerical control (CNC) cut panels are delivered to the assembly site ready for construction, which enables Te Whare-iti houses to be completed within nine weeks. The strength and rigidity of CLT creates a robust building without structural steel or concrete, ensuring safe trucking and cranage.

Visual quality CLT interior surfaces are finished with natural linseed oil. Oiling rather than painting or damaging the CLT surface with strapped lining means the timber remains uncontaminated, promoting future reuse, and enabling circular economy implementation. Lower quality timber previously wasted at the mill is used for the unseen external faces with services, insulation, and cladding attached. With CLT providing both the structure and interior lining, this project avoids costly, time-consuming plasterboard, paint, skirtings, and architraves. The result is elegant architectural simplicity and low-waste construction.

Modular design offers a consideration for the end-of-life cycle of the building, as modules can be disconnected and removed intact for future relocation. This preserves the home’s inherent value that would otherwise be lost through demolition or environmentally forced retreat. Full disassembly is also possible as all joints are dry and able to be deconstructed with minimal material contamination for future reuse.

The BRANZ LCAQuick tool was used to calculate the embodied carbon over the building’s life cycle, see below. (We have not yet modelled the building’s operational energy.)

The upfront embodied carbon (A1-A5) is -4070.9 kg CO2eq. Whole of life embodied carbon (A1-A5, B1-B5, C1-C4) is 18563.62 kg CO2eq. Biogenic carbon sequestered CO2 -27147.24 kg CO2eq and sequestered CO2 exiting system boundary 4067.26 kg CO2eq. The benefits beyond the life cycle module (D) are -4249.10 kg CO2eq. Overall, the total life cycle analysis shows that the project has an embodied energy of 14314.5 CO2eq.

Prefabricated CLT modules provide an opportunity to shift design and construction towards building healthy, affordable, and sustainable homes, without compromising on the architectural design and integrity.