HOW DID NEW ZEALAND arrive at the building controls system we have today? From a background of fire and epidemics in London, New Zealand building controls developed out of the necessity for buildings to be designed to withstand both fire and earthquakes.
Great Fire of London
The Great Fire of London in 1666 started when sparks from a baker’s oven ignited wood stored by the oven, before spreading to the buildings next door. It destroyed 80% of the city although the death toll was only 16.
Buildings at the time were largely built from oak with a coating of tar to keep the weather out. Fire prevention relied on the local population.
Following the fire, London was rebuilt using bricks and masonry, with wider lanes and streets to make passage for firefighting appliances easier.
Industrial Revolution
The Industrial Revolution saw the invention and use of textile machines in city factories replacing hand weaving in the home. The move to factories meant large numbers of people living and working closer together.
The key public health issue was the widespread outbreaks of infectious diseases such as cholera, typhoid, typhus, smallpox and tuberculosis. These outbreaks were a direct result of overpopulated cities, poor housingand living conditions, mass pollution and a lack of a public infrastructure to care for people’s health.
Moving to New Zealand
Fire was also the predominant reason for early regulation of building construction in New Zealand. The Raupo Houses Ordinance in 1842 gave the Governor power to ban the construction of houses made of native straws and flaxes such as raupō, nīkau and toetoe. Twenty pounds was levied annually on anyone building with these materials.
There was, however, a plentiful supply of timber for construction. This was a popular building material for houses and even small commercial buildings until the City of Auckland Building Act of 1856 restricted its use.
There were many instances of fires destroying timber buildings in town centres. By 1858, a fire that destroyed Government House in Auckland was the final impetus for a transition from timber to unreinforced masonry construction for city buildings. In regions such as Wellington where settlers had experienced earthquakes, there was less uptake of masonry construction.
Napier earthquake brought change
Earthquakes are a frequent occurrence in New Zealand, sometimes causing loss of life and significant damage to buildings.
Following the 1931 7.8 magnitude Napier earthquake, which killed 256 people, the New Zealand Standards Institute prepared the first model building bylaw. This was adopted by almost all local authorities and revised and amended from then on.
By 1964, the model building bylaw was known as NZS 1900, covering fire safety, sanitation, earthquake resistance and other aspects of design and construction.
Standards New Zealand, today’s equivalent of the Standards Institute, develops and publishes many building standards now used in building controls. NZS 3604:2011 Timber-framed buildings is one of the most used standards for design and construction of houses.
Many further building regulations
There are examples of further regulation of building construction:
Housing Improvement Regulations 1947, which contained minimum prescriptive requirements for housing including minimum room sizes, minimum ceiling height and kitchen and bathroom requirements.
Drainage and Plumbing Regulations 1959, which contained design and installation of sanitary plumbing and drainage.
Electric Wiring Regulations 1969, which contained the designated installation of electrical wiring in buildings.
There were also many other Acts and regulations with building control provisions for buildings ranging from shearers’ accommodation to export freezing works and crematoria.
Building Act 1991 marks turning point
Development of New Zealand building controls was piecemeal, and by 1979, prescriptive requirements were included in around 60 Acts. These were administered by more than 300 local councils and many private and public agencies. Local government reforms of the late 1980s reduced the number of local authorities.
The Building Act 1991 and supporting regulation was the culmination of the rationalisation of the provisions of the multitude of Acts into one with supporting regulations containing a national performance-based Building Code. Consenting and inspection was initially carried out by territorial authorities and later also by building certifiers.
The performance-based Building Code set the levels that completed buildings and building work must achieve, not the prescriptive way that building work must be carried out. The Building Code was augmented with documents that, if followed, had to be accepted by territorial authorities as complying with the Building Code.
These documents, called Approved Documents and Compliance Documents at different times, contained Acceptable
Solutions and Verification Methods and are not mandatory. Other Alternative Solutions could be proposed in the building consent application as complying with the Building Code.
Leaky homes brought more changes
Weathertightness issues emerging in the late 1980s and continuing to the early 2000s caused homes and apartments to fail to keep water out of the structure, causing rotting of the timber frame. There were two major reports into weathertightness:
The Building Industry Authority commissioned the Report of the overview group on the weathertightness of buildings, known as the Hunn report, in 2002.
The Government Administration Select Committee published Weathertightness of buildings in New Zealand in 2003.
These reports led to the review of the Building Act 1991 and the passing of the Building Act 2004, which contains the introduction of building consent authorities (BCAs), accreditation of BCAs and a licensing regime for building practitioners and a review of the Building Code.
The Building Code was changed with the addition of an extra performance criteria to clause E2 External moisture, and a new greatly expanded Acceptable Solution E2/AS1 was published.
Building for the 21st century: review of the Building Code was published in 2007 and Protection from fire Building Code clauses were amended, along with a new Verification Method and seven Acceptable Solutions.
Canterbury earthquakes lessons adopted
Two significant earthquakes hit the Canterbury region – a magnitude 7.1 near Darfield on 4 September 2010 and a magnitude 6.3 near Christchurch on 22 February 2011.
The Christchurch quake resulted in extensive damage and the loss of 185 lives. While there was no amendment to the Building Code following these quakes, the lessons learned informed other change:
MBIE published extensive guidance documents Repairing and rebuilding houses affected by the Canterbury earthquakes.
The Z factor in the loadings standard was increased, and the definition of good ground was amended to exclude the Canterbury region from the definition used in NZS 3604:2011.
Ground that could be subject to lateral spread and liquefaction was excluded from the definition of good ground for all New Zealand
Kaikōura earthquake 2016
A magnitude 7.8 earthquake near Kaikōura in November 2016 caused two deaths and major damage to road and rail infrastructure along the east cost of the South Island. A significant number of buildings in Wellington were damaged to the extent that they required demolition.
This prompted the review and implementation of the provision for earthquake-prone buildings. Set times were introduced for evaluation and strengthening of earthquake-prone buildings, depending on the risk they pose to people.
For more information, visit www.building.govt.nz/managing-buildings/managing-earthquake-prone-buildings.
Grenfell Tower fire
The Grenfell Tower block of apartments in London suffered an extensive fire that quickly spread up the external façade on 14 June 2017, with 72 fatalities and 74 people injured.
In New Zealand, there was concern about the possibility of a similar fire occurring here due to the combustible nature of the external cladding.
Subsequently, MBIE published guidance on fire spread and cladding choice.
Climate change 2020
MBIE is currently considering feedback on two consultation documents about building for climate change under its Building for climate change programme.
Looking to the future
Events such as fire, earthquakes and weathertightness have increased the volume of information in documents such as:
Acceptable Solutions and Verification Methods – for example, E2/AS1
MBIE guidance – for example, Repairing and rebuilding houses affected by the Canterbury earthquakes.
Looking to the future, regular reviews and updates of the Building Code and supporting documents are planned. Anticipating changes is difficult, but the next steps signalled by MBIE include better product information and embodied carbon emissions reduction.
For buildings to withstand future earthquakes, GNS has instigated a review of the National Seismic Hazard Model, which models the likelihood and strength of earthquake shaking occurring in different parts of New Zealand. The updated model will inform changes to the design loadings codes, building design standards and decisions on building resilience.
Fire will continue to be reviewed as events occur and technology changes become available. The external claddings of high-rise buildings and passive fire are two issues that continue to receive attention.
Designers of buildings outside the scope of E2/AS1 also continue to look for weathertightness solutions.
The health, wellbeing and amenity settings of the Building Code have not been reviewed since the Building Code’s inception in 1992. Questions to ask include whether they are consistent with the government’s wellbeing direction and whether the wider impacts on health and mental health due to substandard housing have been costed. For example, is the Building Code performance for inter-tenancy acoustic insulation appropriate to the medium-density and medium-rise housing developments of today that did not exist in 1992?
For further information please click the link below
https://www.buildmagazine.org.nz/articles/show/building-controls-past-and-future
