Kōrero: Building materials

Whārangi 1. Early houses

Ngā whakaahua

Māori building materials

Māori used what they found in forests and swamps to make houses and other structures. They wove building materials together as they had no nails. They used timber for posts, ridge poles and outer walls, and rushes, bark or toetoe for thatching, which was attached to battens, often made from mānuka. Slabs of tree ferns were used for walls, and reeds for interior walls.

In the 19th century a few wealthier European settlers brought small prefabricated houses to New Zealand from Britain, or small windows ready to install in a new dwelling, when this could be built. But most people had to rely on local materials. In Wellington local Māori helped settlers build shelters of wood, reed, grass and bark.

Earth houses

In the 1840s and 1850s settlers from Dorset, Cornwall and Devon arriving in Otago, Canterbury, Nelson and New Plymouth constructed cob houses. Layers of mixed clay and straw or grass formed thick, warm walls. A stone wall foundation kept moisture from rising into porous walls. Roofs had wide eaves to keep rain off. Outside walls were plastered.

Sod houses were made from squares of turf laid on edge in layers creating walls. Adobe used the same material as cob to make large blocks. These were sun-dried and laid in walls. Pisé or rammed earth used slightly damp soil rather than clay. Rammed into a timber frame it made a kind of instant concrete.

Wooden houses

As the country was heavily forested, the easiest way to build a house was from wood. New arrivals found wooden houses flimsy, cold, draughty and not very private. Many roofs were covered with overlapping shakes (narrow timber tiles split from blocks), or later shingles (tiles sawn from blocks). Other early roofing included fern fronds, reeds, bark sheets, bitumen-coated fabric, canvas and long boards. From the mid-1800s until about 1915, roofs were pitched between 30 and 45 degrees to ensure that rain would run off – in the south, even steeper roofs were preferred to shed snow.

At first timber was hand-cut using a pit saw. A pit was dug under a felled tree. A long two-man saw reduced the trunk to framing and boards. One man stood on top of the trunk and the other in the pit below. In the late 1850s mass-produced steam-powered machines transformed timber production. These included circular saws, reciprocating (push and pull) saws, and gang saws, which cut multiple boards simultaneously. Increasingly sophisticated machinery produced an astonishing range of wood products.

Sources of timber

By 1900, kauri – the most popular timber for construction – was depleted, and mills turned to other native timbers such as rimu and mataī. In the early 1900s Oregon timber was imported from North America, and can still be found in houses of that period. Large production forests of mainly radiata pine (Pinus radiata) were planted from the 1920s and 1930s. Pine can be used in many different ways for building, including laminating, and its generally clean texture means that it can be worked and finished to a high standard.

Light timber framing

Plentiful wood supplies meant light timber framing was the technique most commonly adopted in New Zealand. A skeleton of closely spaced small timbers (typically 100 by 50 millimetres or 100 by 75 millimetres) was covered with plain weatherboards, each of which overlapped the one below, creating a weatherproof skin. Frames were stiffened with diagonal braces to resist the force of the wind.

Treaty treenails

 

The Waitangi Treaty House was prefabricated in Australia and assembled in New Zealand. All the joints were numbered with Roman numerals cut into the adjoining timbers, and the joints were secured with timber dowels or ‘treenails’.

 

In the 1840s and 1850s iron nails were hand-made, scarce and expensive, so frames were assembled using mechanical joints. These might also be secured with a wooden peg – a trunnel or treenail. The most common jointing method was the mortise and tenon joint, where one piece of wood had a hole in it and the other a projecting piece – some were shaped as dovetails. From the 1860s and 1870s cheaper nails transformed construction, allowing frames to be assembled quickly and boards to be fixed with comparative ease.

Wide rough-sawn boards (called ‘deal’) were attached to inside walls and covered with a form of woven jute called scrim. Wallpaper could be attached over this. In utility rooms, and often on ceilings, plain thin boards with the edges chamfered into V-joints covered large areas. Boards were also tongued and grooved, fitting into one another to create a sealed surface which could be painted or varnished.

In more expensive houses and institutional buildings, plaster walls were preferred. Until the early 1900s this was applied over timber laths – narrow thin wooden strips attached to a timber frame. In the early 1900s metal laths replaced wooden ones in some government buildings. Metal laths were strips punctured and deformed, which created a rough surface to provide a key for the plaster.

Me pēnei te tohu i te whārangi:

Jeremy Salmond, 'Building materials - Early houses', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/mi/building-materials/page-1 (accessed 15 October 2019)

Story by Jeremy Salmond, published 11 Mar 2010