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Buildings of stone
Few buildings were constructed of stone in New Zealand and today is more likely to
be used for façade than structure.
By Nigel Isaacs, BRANZ Principal Scientist and Teaching/Research Fellow, School of Architecture, Victoria University of Wellington
F
rom the earliest days of European
settlement, stone has not been the
most used construction material in New
Zealand. In the 1861 Census, only 2%
of dwellings were brick or stone (these were
counted together), 68% were wood and 16%
were canvas. As the country became more
urbanised, and the temporary tent buildings
of the gold rushes were replaced, timber was
favoured because of its ready availability and
ease of construction. By 1901, only 4% of
dwellings were brick or stone, whereas 90%
were timber. Stone was often used in prestigious
buildings, such as churches and town halls.
Not all stones good for building
Stone is heavy and durable, and although
strong in compression, it is weak in tension,
and its earthquake performance is poor without
reinforcing. Most rock types are good conductors
of heat – for example, the R-value of limestone
(0.04 m²°C/W) is only one-tenth the R-value
of the same thickness timber at 0.4 m²°C/W.
Much heavier rock can store heat from the day
and release it in the cool of the night, creating a
more comfortable environment.
Not all stones are suitable for use in building.
A building stone needs to be readily workable,
strong and durable, have a suitable appearance
and be fit for purpose. For example, Tonga Bay
granite (from Tonga Bay in Abel Tasman National
Park) was used for buildings in the 1890s, but
it crumbled badly and would not retain a high
polish. Today, it can only be seen in the steps
built in 1913 leading up to Nelson Cathedral
and on the exterior of the 1908 (former) Public
Trust Building in central Wellington.
Although decorative stones may be trans­
ported long distances, building stones were
normally selected from locally available material.
Examples include basalt lava in Kerikeri, scoria
in Auckland, greywacke in Nelson, marble in
Takaka, limestone in Oamaru and schist in
Central Otago. Early settlers either used their
86 BUILD April/May 2009
Isel House, Stoke. The front section, completed in 1915, uses local river boulders with bricks providing colour contrast.
own skills or the services of skilled masons, if
available. The use of local stones resulted in the
development of local industries with the skills
and expertise for its cutting and construction.
Stones’ differing performances led to their
use in different situations. Granite, for example,
is generally resistant to chemical damage, but a
spot of vinegar quickly damages marble.
Type of building stones
Two main wall types
Building stones are classified by the origin
of the rock, and all three types are found in
New Zealand:
❚❚ Igneous – formed from the cooling and
solidifying of molten magma from deep
within the earth. This can be hard and strong
(for example, granite, basalt, quartz) or,
when formed from ash and pumice deposits,
more variable like ignimbrite.
❚❚ Sedimentary – formed from sediments that
accumulated in layers under the sea, lakes
or river valleys and were then compacted.
These are less durable, and examples
include sandstone and limestone.
❚❚ Metamorphic – igneous or sedimentary rocks
that have been modified by heat, pressure
and/or hot gases or solutions. Examples are
marble, slate and schist.
Many stones have local or trade names that
may disguise or even incorrectly state the type.
Among the most well known are Oamaru stone
and Hanmer marble (limestone), Halswell stone
(basalt) and Hinuera stone (ignimbrite).
Although there are many types of building stone,
two main wall types can be used individually
or in combination. ‘Ashlar’ uses shaped and
formed pieces of stone, whereas ‘rubble’ uses
rough stones either as found or further shaped.
Although mortar (lime or cement) can be used
to both hold the stones together and give shape
to the construction, walls can also be laid ‘dry’,
with the friction between the stones giving the
strength.
The brick and stone front part of Isel House
at Stoke, near Nelson, was completed in 1915.
The rubble construction used the river stone
from nearby Poorman’s Valley, with local bricks
used to provide contrast around the windows
and corners.
Stone from near and far
Early settlers made use of stones from the land
the house was to be built on and nearby fields
or rivers. Once transport was available, stone
could be brought from further afield, although
the cost was limiting for private buildings.
Public buildings were less constrained,
and could even attempt to provide regional
representation through the materials. The current
Parliament House in Wellington, built between
1912 and 1922, replaced the timber structure
destroyed by fire in 1907. It is faced with Takaka
marble on a base of Coromandel granite.
The marble was extracted from the Kairuru
quarry on Takaka Hill using traditional tools and
techniques. The photograph shows the ‘plug
and feather’ method in use – a development
of the even older ‘wedge and groove’ method of
quarrying stone. A row of holes was drilled into
the marble and a ‘feather’ of two pieces of steel
inserted. A ‘plug’ was then driven into each
‘feather’, pushing the two pieces of steel apart,
ultimately fracturing the marble and splitting
off a large piece that could be further split into
suitable sized pieces.
More recently, power tools have revolutionised
the extraction of stone. Drills, wire cutters,
chainsaw cutters and circular saws permit
stone to be more readily and efficiently quarried
and then cut to size and shape, to be finished
as required.
Oamaru’s Victorian buildings
Men cutting marble for Parliament Buildings in about 1920 at
Kairuru quarry, Takaka Hill. (Leslie Hinge, Alexander Turnbull
Library Ref: 1/1-021976-G.)
Around Oamaru, limestone has been quarried
since the 1860s. In 1862, the government
land sales notice reported that a ‘superior
limestone abounds and is generally used for
building purposes in the town of Oamaru’.
The agricultural wealth of the time supported
the construction of substantial Oamaru Stone
buildings, many of which form (in the words
of the Oamaru Whitestone Civic Trust) ‘New
Zealand’s most complete collection of Victorian
buildings’.
Façades and many uses
Earthquake and other safety requirements,
coupled with the reducing cost of other
construction systems (including concrete and
steel framing), have meant New Zealand and
imported stone is now used more for façade than
for structure. Despite this, New Zealand stone
can still be found in road curbing, stock or house
fences, memorial arches, decorative surfaces
in buildings, tombstones, statues, pedestals,
plaques, steps, benchtops and roofing slates.
The article benefited from Granite and
marble – A guide to building stones in
New Zealand by Bruce W. Hayward, published
by the Geological Society of New Zealand in
1987.
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