Koia Architects select innovative 45mm structural cavity system & Rosenfeld Kidson timbers
- Western red cedar cladding blends Southland exterior aesthetics of high country resilience, and provides interior glow.
- Innovative new 45mm structural cavity system enables improved weather protection and ventilation while allowing more depth around windows for a clean exterior profile.
- FSC 100% certified Garapa hardwood decking timber marries perfectly with the chosen materials and surrounds.
Koia Architects designs Law House in the Wanaka hills
The Law house is a superb example of New Zealand architecture with cool clean lines and a breath-taking outlook over Lake Wanaka.
Designed to complement and enhance the spectacular natural landscape, the Law House utilises its great location and aspect to maximise views and energy efficiency. Wide windows and decks on two sides provide a nearly continuous outlook and a feeling of being connected to the dramatic and spacious surroundings.
"We have worked hard to ensure the building blends with the environment. The timber cladding is a very important component of this. The Rosenfeld Kidson corner and jamb profile is a beautiful way to detail these junctions. The window flashing system we developed has been refined to work with this and ensure the water protection, drainage, air seal and insulation all align as they should."
Tony Koia, Principal Architect, Koia Architects
For the house’s distinctive exterior cladding Koia Architects chose Western Red Cedar. Cedar has a very low shrinkage factor and therefore is very stable.
"Many builders in Wanaka will only use cedar as their timber cladding. The climate has a very low humidity which causes significant shrinkage. It can cause damage to any antique furniture on the inside of a house and the exterior of a house is a much harsher environment." - Tony Koia.
Western Red Cedar varies from dark brown to pink and readily accepts stains and oils to provide a wide choice of palette. Available in an endless variety of profiles, finishes and coating products, cedar provides designers and architects with great design flexibility.
Western Red Cedar was also employed for internal panelling throughout the Law House.
"We wanted to create a 'warm glow', reminiscent of a ski lodge, to the living room. In a bright large glazed area, cedar panelling absorbs the light and minimises glare.
Using cedar for the interior has worked really well to link the exterior to the interior, and combine with the local schist and break up other flat painted surfaces. - Tony Koia.
The 45mm structural cavity system utilises a structural 45mm Radiata cavity batten with vertical shiplap Cedar weatherboards. The ventilated cavity batten is fixed to the wall framing without requiring additional supporting dwangs or nogs meaning it is much easier to install.
The primary benefit of a 45mm structural cavity system is that the cladding only needs to be fixed to the batten itself and not through the building envelope, helping to maintain the integrity of the air seal. The 45mm structural cavity also allows for improved drainage and ventilation.
"With the 45mm structural cavity system, the exterior nails do not penetrate the RAB board lining, which means there is significantly reduced risk of water penetration and better pressure equalisation.
There is less risk of water or air leakage, and the better ventilation provided by the system means better drying. Windows and doors can be recessed to the insulation and RAB board line to ensure these are a continuous line around the perimeter." - Tony Koia.
The greater cavity space provided by the 45mm structural cavity system allowed the recessed windows in the Law House design to be brought forward to the outer line of the framing, rather than recessed behind it.
Attractive, hard wearing timbers that suit Wanaka’s stunning landscape
Koia Architects specified Garapa for the striking deck of Law House. Garapa has a history of success in New Zealand, tried and tested in our country’s varied climatic conditions for almost a decade.
Garapa is a honey brown colour with a very fine finish which appealed to Koia Architect’s Tony Koia on an aesthetic level.
"I think the colour and grain of Garapa wood is better suited to Wanaka than most timbers, as it blends beautifully with the natural surroundings." - Tony Koia.
Because Rosenfeld Kidson’s Garapa is a kiln-dried timber, it delivers great properties of stability in addition to its great durability. Garapa also does not suffer end-checking or leach staining tannins in the way some other hardwoods can.
As well as having many superior properties compared to other hardwoods available on the market, Garapa is environmentally certified as FSC 100%, which is the most stringent third-party environmental standard available.
"We had designed an outdoor bath which is hidden under a removable deck cover. This meant we needed a timber that wouldn’t leach into the bath, so we wanted an alternative to Kwila. We also wanted a more sustainable hardwood, and the colour of Garapa made it an attractive alternative." - Tony Koia.
A great builder ensured the vision was faultlessly realised
"It is essential to have a quality builder at any time and Tony Quirk Builders have been great. Their attention to detail has been particularly impressive in aligning the cedar sacking to the interior to the doorway openings; and it is this quality that is needed to create architecture." - Tony Koia.
About Koia Architects
Koia Architects was established in Auckland, New Zealand in 1995 by architect, Tony Koia. The practice has expanded over the years and a second office was established in Queenstown in 2004. Each commission is special and unique. Every client brings a different hierarchy of requirements and Koia Architects identify these at the outset - whether they are aesthetic, quality, time or budget constraints - so a successful outcome is achieved. For more see www.koia.co.nz.