CONCRETE HOUSES

Evening Post, Volume CXL, Issue 102, 27 October 1945, Page 9

CONCRETE HOUSES

IN PLACE OF TIMBER

A PROMISING SYSTEM

In their search for a substitute for timber, the technical officers of the Housing Department have kept an open mind. They have welcomed suggestions from practical builders, and from amateurs too, who claim that .they have the solution of how to build the ideal home—cheap, permanent, weather, pest, and maintenance proof. There have been plenty of ideas;- but many are so extreme as to warrant no encouragement, and gene-, rally a plain test is applied: Will the originator undertake to build, or have built, a small line of these new homes, say, two? three, or four, at a cost, say, comparable with the cost of a timber house? Not so many stand that test, for nine times out of 10 the reaction, is that "this system" is highly economical when employed on a grand scale, but is hardly applicable to an individual house or even to a line of samples, because,, obviously, of the preliminary outlay upon plant. And, anyhow, doesn't the country want homes by the thousand?

The country does, but contrary to a wide impression,- the Housing Department is not the Henry Kaiser of New Zealand, -building a home an hour, or a day. The Housing Department does not itself build houses, and for all the homes it promotes it relies upon the private builder. More than that, it relies today upon the small .man, or the small co-operative party, to a far greater extent than upon a few large construction companies, though it will require all the resources of the small and the large builder to overcome the shortage of houses for the next few years. For mass production and prefabrication to be successful material must come to hand at the exact time and in the quantity required, so that air can dovetail together according to the production schedule; mass production of houses is a possibility, but not a practical one until ample supplies of material are available.

IDEAS UNDER PRACTICAL TEST.

There are in the Hutt Valley, at Miramar, and in other of the larger housing blocks a number of houses of experimental and semi-experimental types, which were considered by the Department's officers to be sound in promise and which were backed by those who put forward the ideas by their willingness to go ahead and build them at a reasonable price. All of them aim at reduction of the quantity of timber. Some are in .brick, but a brick remains a brick, and these trials are mainly of variations of construction towards cost reduction or speed of construction; all brick houses in the blocks have earthquake safeguards which were missing in earlier home building. ( Concrete is a logical substitute for timber in this country, for there, are unlimited supplies of gravel and metal, and the periodic shortages of cement can be overcome, but concrete homes so far have not been widely satisfactory. The common faults of coldness, dampness, and sweating can be overcome by cavity wall construction or one or another of alternative plans of wall ventilation, but then costs climb until concrete cannot compete with timber.

"NO FINES CONCRETE." Working from an English experiment first publicised about 1923 and increasingly used until the war stopped home building there, the Housing Degartment is making practical test — y having houses built for people to live in—of an interesting and promising single concrete wall," mixed so coarse that capillary action cannot take place. "No fines concrete" is the term given it, and the mix, of half-inch broken metal bonded with straight cement, is so open that wind passes through an unplastered six-inch wall as an appreciable current, but not a sign of dampless showed through such an unfinished southerly wall during the spell of springtime weather Wellington put up with last week, nor does a nose, played full-bore from a couple of feet, make any showing on the inner surface. Less cement is used than in standard mix; pouring is not complicated by need of agitation, and with the simple and effective boxing used —the idea of a Christchurch builder, but open to anyone—three men Can complete the main and partition walls in nine days, using no scaffolding, profiling, or other gear for truing up, other than the boxing itself, and planks, carried on -the boxing brackets, from which to pour. The open texture of the concrete gives an ideal surface for the plasterers following on.

BUILDERS INTERESTED

Because so many claims have been made in the past for new methods of handling concrete and so many have slipped in practice, no one is being positive about this single, weather, damp, and sweat.proof wall, but visiting builders have been greatly interested, both in the mix and in the system of boxing. They reduce the timber required to the bare minimum; the boxing cpmes away remarkably clean and moves from job to job.

In other districts different coarse mixes are being tried; in the Rotorua district, for instance, eight-inch walls of screened pumice will be used. Reinforcing is used only in the foundations and in a tie band at window-top level.

More advanced tests are being made with concrete flooring, using a "warm" mix with a resiliency comparable with that of wood and with comparable wearing and appearance qualities. There is nothing new in "warm" mixes; in Britain and Europe, where stock are housed through the winter months, warm mixes have been used for years, but we are bound by convention to wooden floors in New Zealand homes. However, there are undoubted possibilities in the non-timber floor and trials are being made.

With the one-skin wall that behaves like the more expensive cavity wall and can compete in price with timber, with warm concrete for the floor, and with a concrete roof that does not leak, we may, as practical experiment shows the way, reduce the timber in the New Zealand home to the doors, cupboards, and window frames, but that is some way ahead. The practical trial is the way to find out; the human being is far superior to the guinea pig; : it can protest if the experiment annoys.