Economic cycles, war, the Napier earthquake, housing shortages, and trends in building regulation and training all influenced house design during the 1940s to 1960s.
A housing shortage that existed in New Zealand during the 1920s became even more acute following the Depression years of the early 1930s.
Around 7,000 building permits were issued for new houses in 1927, according Cedric Firth’s book, State Housing in New Zealand, but by 1933 the figure had fallen to below 1,500. This was at a time when 6,000–7,000 new homes were required annually for a growing population. By the late 1930s, the housing shortage, estimated to be around 20,000 dwellings, was extreme.
The shortage continued during the war years, compounded by a shortfall of both skilled labour and building materials. Copper, steel, zinc, electrical cable, conduit, and paint ingredients, which were required for the war effort, were largely unavailable for house construction.
In response to shortages, the government introduced legislation to control the sale and use of building materials and the issue of building permits. Only construction considered to be essential was permitted. Domestic building was to meet the housing needs for families only (it was almost impossible for single people to build), and construction had to be economical.
These controls, which continued until well after the end of the war, had a significant influence on the construction of houses both during the war years and in the post-war period.
The Government also played a role in housing design through legislation and education. The original model building bylaw, NZS 95, was introduced in 1935 as a result of the Napier earthquake, but it was not until 1944 that Part IX, Light Timber Construction, was added. NZS 95 did not become enforceable until adopted by a council as a local bylaw – often with local modifications.
NZS 95 was replaced in 1964 with NZSS 1900 Model building bylaw. Chapter 6 Construction requirements for buildings not requiring specific design, Division 6.1, Timber which gave the framing requirements, was essentially no different to the original.
In 1951 a new Chapter 7 Small chimneys and appliance installation was published which superseded the 1935 provisions of NZS 95. The original NZS 95 document called for reinforcement in the chimney flues and timber boarding adjacent to the chimney. The 1951 Chapter 7 introduced the tying of chimneys to the timber structure or required that they otherwise be designed as self-supporting. An amendment in 1959 deleted the need to include the surrounding timber boarding.
At the same time, the state housing specification was developed and amended. At its first issue in 1936, it required continuous reinforced concrete perimeter foundation walls. The reasons were not for earthquake resistance, but rather to prevent termite infestation and to cater for the expansive clays in Auckland. However, by co-incidence the practice was good for earthquake resistance.
The 1946 issue of the specification probably presented the biggest backward step in the earthquake resistant design of timber houses. Since termites were no longer seen as a problem, the continuous perimeter foundation requirement was removed in favour of piles. One further backward step was a relaxation in the requirement for securing roof tiles to every alternate tile.
The New Zealand Trades Certification Board was established in 1949 to develop a national trade qualification. The Technical Correspondence School opened in July 1946. In 1958 the Technicians’ Certification Authority of New Zealand was established, with the mandate to prescribe courses and syllabuses and conduct national examinations. The first technical or trade training institute was established in 1960 – the Central Institute of Technology in Petone.
The book Carpentry in New Zealand was first published by the Department of Education in 1958, and this provided the guidelines that defined building methods for light timber frame construction for many years.