Residential Concrete Masonry Building Systems
Concrete masonry has a long history of use in New Zealand as a domestic building material. Many notable homes have been designed and built using this versatile product. Construction of masonry homes can be very economical, particularly when the designer uses the modular sizes of the masonry units to full advantage in an effort to minimise wastage.
Masonry serves as a type of permanent formwork for concrete. The grout fill works in conjunction with the steel reinforcing to provide structural strength.
Masonry is available in a wide range of shapes, textures and colours; and in units suited for a variety of building surfaces and elements. The range of block products is expanding as blocks with special finishes, sizes and thermal properties emerge in the market.
The construction of masonry homes has been simplified with NZS 4229:1999 Concrete Masonry Buildings Not Requiring Specific Engineering Design. This document makes it possible to design a masonry home without a structural engineer, in a similar manner to the application of NZS 3604:2011 Timber-Framed Buildings to the design and construction of light timber framed houses.
Masonry For High Mass
Concrete masonry presents a number of options for use in a high mass home. These options allow insulation to be incorporated in the construction in several ways, helping to ensure effective storage of heat.
Walls insulated on the inside face (using sheets of polystyrene, for instance) isolate the mass of the wall from internally reflected and radiated heat. This can reduce some of the benefits of the high mass system, but can make the location and alteration of services very easy, as they are usually located in rebates cut in the polystyrene. Wallboard cladding systems are then easily fixed to this and decorated accordingly.
Walls can be insulated on the outside face using either polystyrene or an insulating plaster system. The insulating plaster systems enable the designer to select a variety of finishes and textures that can be applied to the surface. One block manufacturer supplies a polystyrene biscuit in the core of the block as the insulating medium. The thickness of this insulation is able to be increased for use in the lower temperature areas of the South Island and higher altitudes of the North Island.
A double skin construction system, where a structural masonry wall is clad with a masonry wall veneer, allows an internal cavity which can be insulated. The use of a cavity is also a very effective method of waterproofing.