In the 7 million years that the human species has existed, over 99.99% of our evolution has taken place in a natural, outdoor environment. This has continued through the beginning of mass urbanisation from the industrial revolution, with a very small amount of time spent in an artificial, urbanised environment. Consequently it’s reasonable to conclude that humans are primarily adapted to a natural setting and research clearly shows that natural environments have a positive effect on our wellbeing.

Biophilic design is a synthesis of principles for designing the places where people live, work, heal and learn. It recognises that we need nature in a deep and fundamental fashion, but we have often designed our cities and suburbs in ways that both degrade the environment and separate people from it.

When used well wood creates buildings that combine many key elements biophilic design, including natural light, air flow and views of green spaces. Wood can also be used to reflect the patterns and shapes seen in nature, known as biomorphism, and as a natural material on display in a building.

This Guide provides an introduction and overview based on typical engineered timber buildings while considering the relevant factors to take on board in order to provide appropriate estimates.

The value proposition of Engineered Timber goes beyond lowest price mentality and more about when is it appropriate to use and seeking to quantify the Sustainability benefits, Health Safety and programme efficiency which should be part of the assessment to highlight the true benefits of Engineered Timber Solutions.

The WPMA, in conjunction with NZ Wood Design Guides, has recognised this need and set about implementing a suite of new and revised Timber Guides. Engineered timber products available in New Zealand, for use in construction, has technically evolved to be able to offer superior products that compete with traditional steel and reinforced concrete options. Encouraging the construction industry to adopt innovative approaches, needs information and evidence. In order to show the value proposition of timber construction requires some guidance.

The familiarity of wood products in New Zealand’s industry is its advantage. Utilizing the most familiar product in the evolution of construction is the next logical step.

The wood processing industry has recognised the trend and provides a growing and evolving product range. LVL, CLT, Glulam, PLT, light timber-framed wall and floor panels and many other complimentary products are offered to realise various structural and architectural solutions. Components become larger and more precise, providing the opportunity for more efficient construction processes. Although timber is a familiar product, large scale timber components made from timber and their assembly methods are not.

The scope for contractors is changing with prefabricated timber products, an unfamiliar terrain for most. Risks have increased and are largely unknown, opportunities are substantial. At the end, higher productivity will convince, ensure the success of the most versatile companies and change the approach to the delivery of construction projects.

Recent New Zealand earthquakes have shown the excellent resilience of timber buildings under seismic loading.

Timber houses and other timber buildings generally showed excellent structural behaviour in the 2010 and 2011 Canterbury earthquakes and in the 2016 Kaikoura earthquake. That excellent structural behaviour was observed in light timber frames houses, timber log-style houses, and timber commercial, industrial and educational buildings.

The few timber buildings which suffered significant damage had design flaws or were located on unsuitable sites with inadequate foundations. The excellent behaviour of timber buildings in earthquakes results from the low weight of the buildings and the flexibility of timber structures.

This design guide is an introductory design guide produced with the aim to help designers produce cost-effective multi-residential timber buildings for the New Zealand context. It is intended for residential buildings and does not cover commercial buildings. In practice, this means that relatively small, apartment-sized rooms are assumed, rather than large halls.

In this design guide fundamentals of acoustics are presented first along with the New Zealand building code and local authority requirements. The reader is then introduced to some principals for improving acoustic insulation in timber building elements. Finally, some example details are presented for timber frame construction and for massive timber (CLT) construction.

Because wood burns, many people assume that all timber buildings have poor behaviour in fires. However, where necessary, timber buildings can be designed with excellent fire safety for the occupants, and sufficient fire resistance to prevent spread of fire or structural failure.

Timber structures tend to fall into two distinct categories; “heavy timber” structures and “light timber framing”. Heavy timber structures are those where the principal structural elements are beams, columns, or panels made from sawn timber, glue laminated timber (glulam), laminated veneer lumber (LVL), or cross laminated timber (CLT). Light timber framing consists of timber stud and joist construction, typical of New Zealand house construction.