Lasting Konka heritage

MADE TO LAST: A Kosy Californian bungalow in Gonville, made from Konka board which used pumice. PHOTO/KAREN WRIGGLESWORTH, 2015 09102015WCSUPKONKA1

MOST early New Zealand houses were built from timber or brick, but by the early 1900s many new products were being developed. Monolithic concrete claddings called Oratonu (patented in Dunedin in 1911), Fabricona (1940s), and Pearse's Patent (patented by a Feilding builder in 1920) were all developed in New Zealand.

The specialty in Wanganui was a concrete cladding innovation called Konka board, developed around 1912 and used through to the 1960s. By 1922, 80 per cent of new Wanganui houses had Konka board cladding.

A Government test on a 7-year-old Konka-clad home in Castlecliff in 1921 found the cladding so tough that pickaxes and crowbars were required to penetrate it. A seaward spot was tested, and framing and nails were found to be in perfect condition.

Konka board was a panel cladding system that used powdered pumice instead of sand as an aggregate, flax fibre for strength, and a waterproofing mineral called pudlo. The pumice meant panels were lightweight, and houses were warmer in winter and cooler in summer. Konka board walls were also damp, borer and fire-proof, and were much cheaper and quicker to install than traditional alternatives.

Panels were held in position with patented galvanised steel clips, and were suitable for internal and external walls. Joints were covered with hessian (sacking) soaked in wet cement and the whole surface was then roughcast/stuccoed.

Konka board was labour-intensive and required a lot of space to make, and these were key reasons for the product's eventual decline. The boards were made by filling flat, paper-lined frames with a hand-mixed concrete-pumice slurry. Flax fibre was added, and the boards were cured for three days, after which the frames were removed and the boards were hung to dry. Drying times depended on airflow and humidity - no steam chambers or kilns were ever used.

Konka board was patented by RM Maunder of Palmerston North in 1915. It is unclear when and how it came to be manufactured by Bassett and Co in Wanganui, but there were public disputes about patent infringements in later years.

In August 1918, due to difficulties connected with the war, an article announced that the business of Green and Beaven, Timber Joinery, Cement and Konka Merchants, would transfer to Bassett's.

Fred Beaven joined Bassett's, while RW Green moved on. An article in the Chronicle in May 1919 states that Bassett and Co were "the Dominion manufacturers for the patentee", and a 1923 article states that Konka manufacture and distribution were now controlled in Wanganui.

Bassett's (now Carters, and still on the company's original site) was established in Wanganui by engineer William Bassett in 1874. Konka was a winner because of abundant local supplies of pumice (from caves at Papaiti) and flax (from between Ingestre St and Dublin St).

Konka board was widely used in Wanganui during the 1920s, when Californian bungalows were replacing Victorian and Edwardian villas as the homes of choice. It was also used in many post-war homes. Bassett built hundreds of Kosy Konka homes from 1914 to promote the product. The development of solid concrete foundation walls around the same time was also beneficial, as brick foundations tended to slump when loaded with stuccoed walls.

By 1928 a dispute had arisen between Wanganui Sash and Door Factory, and the patent-holder RM Maunder and Wanganui-based AD Beaven over the validity of the Konka patent.

The Court of Appeal found in favour of Maunder and Beaven in 1928, but in 1929 the Privy Council upheld the company's objections (among other matters, that the product was 'discovered' and so could not be patented). In addition, the product could easily be copied, and with minor modifications would not breach the patent.

By the 1960s, mechanised manufacturing processes made alternative cladding products more cost effective to produce. Attempts to revitalise Konka board by rebranding it Bassetts Beta Board, and later Wanga Board, proved futile. The time for hand-made products had passed, but Wanganui's Konka heritage can still be seen throughout the city.

- Karen Wrigglesworth is a Whanganui engineer, writer and a research volunteer at the Whanganui Regional Museum.