Home-Building Experiments

Press, Volume CVI, Issue 31221, 19 November 1966, Page 27

Home-Building Experiments

A bold experiment in j home-building with uncon-) ventional materials is being) made at Porirua East, for the j Housing Division of the I Ministry of Works. The result might be muchl less reliance on some| imported items, notably copper, and much less need) for dwindling supplies of I native timbers.

Many kinds of material are being used in the two threebedroom houses in Fantame street that are the subjects of the experiment. They range from load-bearing wall-panels of precast concrete to rainwater, drainage and sewage pipes and fittings that are made of a rigid plastic, polyvinyl chloride. Radiata pine is being used for window frames and sashes. The houses are expected to be finished before Christmas. Research will then be based on them, and the performance of the new materials, components and methods will be assessed. One house is 1150 sq. ft and the other, alongside it, I is 1050 sq. ft. J. R. Dunlop 1 Construction Company is ibuilding both. The larger one can be called the “concrete house.” ; It has no conventional ' foundations; instead, the site ) was excavated 6in. for the 'whole area within the perimeter of the house. The topsoil was replaced by hard fill (shingle and broken stone), which was then given a topping of well-watered clean sand to form a smooth, firm base. This area was then rolled and consolidated to a smooth surface, on which polythene film was laid to block rising dampness. A concrete slab, 4in thick and reinforced with steel fabric, was then placed on packing blocks of cast concrete. The next step, to be taken in the finishing stages of floor ) construction, will be to proi vide a smooth surface of | cement plaster tin thick. Thick vinyl tiles will be laid I in the hall and lounge, and I linoleum elsewhere. ! Concrete floors are not new I here or overseas, but if they ! are shown to be suitable and

economical in State housing their use could save native timbers, such as matai and rimu, in sub-floor framing and in flooring.

Panels for Weatherboards The outside walls of this house are sheathed with pumice-concrete panels instead of weatherboards. The panels are 18in wide and are linked by rebated joints. They are 2in thick, with webbing 4in thick at the outer edges and at the base. Each joint carries a polyvinylchloride plastic gasket to ground level. This is a protection against leakage through the joints when the concrete expands or contracts. The use of these panels for external walls saves matai or rimu weatherboarding. The internal wall-linings are gibraltar board, with removable panels so that the framing and exterior sheathing can be inspected. The roof, of concrete tiles, is pitched at 20 degrees instead of the usual 32, thus requiring fewer tiles and less framing. The roof frame is of prebuilt trusses, its sections being connected by gang nails when placed in position. A gang nail is a massproduced steel plate incor- ) porating 10 nails. This method permits the use of lighter wood, in trusses each 3ft instead of rafters the usual 18in, again economising in heavier timbers.

Flooring, outer walls and roof are all of concrete. Plastic Pipes

Spouting and downpipes, cold-water pipes, vent pipes, traps and wastes, and stormwater drains are polyvinylchloride plastic instead of cast iron, copper, lead or earthenware. “P.v.c.” is not only lighter but also cheaper than the normal piping made of imported raw materials.

If has not, so far as the Housing Division knows, previously been used in New Zealand for soil pipes, wastes and traps. Clean radiata pine, free of heart, has been used for casement window frames and sashes in this house, and the smaller one. It was treated to Timber Preservation Authority specifications and kilndried. Heart of radiata pine cannot, in the opinion of the Housing Division, be satisfactorily treated against decay and is not durable.

The joints were metalpinned and sealed with water-

proof glue. Galvanised screws were used instead of cadmium plated. The sashes of one house were pre-treated to make them water-repellant. Comparison with the others will be made later. Solar Water-Heating Solar water-heating is an important part of the experiments. The Housing Division has already successfully tried it as a boost to-electricity in a house in Cumberland grove, Porirua East, where the only economy test was with electricity accounts. These have been a third to a half less than in other houses and the water is at times hot enough to allow the electricity to be switched off. At Fantame street, the Housing Division aims at exact comparisons. One of the two experimental houses will have a solar water-heater as a hot-water booster. The other will rely solely on electricity.

A kilowatt-hour meter in each will measure separately the power consumption for water heating and a watermeter in each will measure the draw-off. Thus, regardless of how much hot water either set of tenants uses, the financial advantages of a solar-boosted system can be accurately gauged. At the Cumberland grove house the copper-piped, glasscovered black base collector that attracts the sun’s rays is mounted on the exterior wall at the back of the house, facing north. In the larger house in Fantame street, the collector will be mounted over the roofing titles on the northwest slop. This is aesthetically more pleasing and also better for houses with outer walls not suitable for mounting a collector. The Department of Scientific and Industrial Research (physics and engineering laboratory) has done much research into solar heating and devised the systems for both Cumberland grove and Fantame street. Its officers will supervise the Fantame street installation and make the subsequent checks. Taking into account the cost of the apparatus, a special 40-gallon tank, and installation, the basic test for

the solar water-heating system is that it should pay for itself in five years in savings over a hot-water system using electricity alone. This experiment could have significant results. At least half the electricity generated in New Zealand is used for domestic purposes, including heating water. Widespread use of solar heaters, which would be much less expensive if mass-produced, could lessen the demand on the national electricity grid. Roof Nearly Flat

The smaller house has conventional foundations but here, particularly in materials, resemblance to the average house ends.

With a pitch of four degrees, the roof is almost flat. It is covered with long-run metal sheets. The few inches space between the roof and ceilings is insulated with fibre glass against extremes of heat or cold.

Flooring is Jin high-density particle board. The floors were prelaid, the framing of the house following. This was a reversal of ordinary practice. Hardboard, 12in wide with a liin overlap, forms the weatherboarding. Building paper has been placed between the external sheathing and the timber frame and double-sided paper between the frame and interior walllining. This is the first known time this hardboard has been used as weatherboarding, except in staffhouses built by the manuacturers in Tokaroa. There is no water-supply tank on the roof of this house, and lack of space above the ceiling leaves no room for one inside. Instead, the hotwater supply tank will be fed direct from the main supply by means of a pressure-reduc-ing valve. Several types will be experimented with. Both houses are being fitted with polyvinyl-chloride syphonic cisterns in the toilets. Sewage and vent pipes are four-inch p.v.c. Each house will have a stainless steel washing tub. I The photograph shows the concrete house, with concrete floors, pumiceconcrete panel weatherboards and concrete tile roof.