CONCRETE HOUSES.

Sun (Christchurch), Volume VI, Issue 1808, 29 November 1919, Page 11

CONCRETE HOUSES.

TWO SYSTEMS OF BUILDING, j MONOLITHIC PRINCIPLE CONDEMNED. It was announced during the week that the Government had made a contract with a Wellington builder for the erection of 66 dwellings with solid concrete walls. There is a good deal of difference of opinion regarding the use of solid concrete walls in this climate, which, in the opinion of experts, demands the use of hollow concrete walls. Some comments on the Wellington proposal are contained in the article published below. There is no comparison between a continuous-cavity wall of two 3in thick blocks set in cement mortar and cross tied with metal ties, making a Din wall | overall, against a wall built of 6in poured concrete in one solid wall, 6in overall, known as monolithic or ferroconcrete construction. ! The advocates of solid concrete monolithic walls are running a great risk in regard to damp houses. In the first place, concrete is a great conductor of damp, as well as cold. Providing a cold atmosphere prevails outside ami a hot one inside, condensation will result.*on inner walls, as is seen on glass windows. Freezing companies throughout the Dominion do not use concrete, because it so readily conducts the cold air outwards, if used as solid walls. Solid concrete walls are only suitable for tropical countries. Solid concrete block walling is extensively used in India, Africa and the Canal zone with great success for the coolness it gives. In countries further north it is entirely unsuitable unless used with a continuous cavity—practically an inner skin within an outer skin is an absolute necessity for countries situated such as the United Kingdom and New Zealand, which experience bleak winds, accompanied by driving rains. The Norwegian Government is building house walls with a double air space, showing that the colder the climate the more necessity for air insulation.

Waterproofing the rough-cast plaster on the outside of a building, even if it stops the rain from penetrating, does not alter the temperature of the concrete, and condensation goes on as before.

The drawback to monolithic walling is that it standardises the design. To change design and plan is ( to. spoil all chance of cheap building. When 'wealthy American corporations have to call in the aid of town planners to place monumental giant match-boxes on new garden city sites for their employees, they obtain variety in the plotting of the property, in setting the houses out of alignment, and in groups rather than rows. Variety is further enhanced by the varied topography of the land and the irregularity of the streets. Further variety is attained with lattices, pergolas, entrance hoods, and in minor details. All this is bad chough, but how is the New Zealand Government getting on in buying rows of sections in suburbs and having two match-box designs in 200 houses? The remedy for this is concrete block building and planning with this system of continuuous cavity walling. By the adoption of the unit system of blocks and fractional blocks, the blocks always being a division of the length, height and thickness of walls, any plan can be built with as much ease as straight walling, including for pieces and projection courses. Design blocks, including rock face, panels, etc., can be used to break with plain blocks, interchanageable throughout.

A factory putting out 1000 blocks a day, stamping any variety of• design asked for, would soon cope with a house containing 3000 blocks, and, given a fair supply of concrete block-setting labour, houses would rise very rapidly. By the adoption of the winning designs at the town-planning conference, the Government as easily—by the block system alluded to —build 20 or 30 different designs as cheaply as the two referred to in the solid concrete. The monolithic houses have to be coated with stucco. Window-sills must | be worked out in plaster, and at 3/6 per

yard are a heavy item per house. Inside, the same system has to have two coats of plaster to make a job, which cannot be done under 2/- per yard —another burden in cost. The continuous cavity block, on the other hand, when laid, needs only a cement-coloured wash, on account of the finely-pressed face, and pointed down in finishing for outside walling, costing 30/- per house. Inside the same block needs only a skin coat of the present" plaster materials commonly called setting, at a cost of Od to 9d per yard. Washhouses, coalhouscs, etc., do not even need this, as the surface is good enough for colour only. The optimistic builder in Wellington who is going to show the way how to build concrete houses iiQ not built them yet, and it will be interesting to hear the tenants' remarks after the first winter spent in them if it be a rather wet and cold one. Solid concrete, whether block or monolithic walls, are only fit in this country for .stables, outhouses, fences, etc. No architect would even dream of putting up a brick or stone house otherwise than hollow, and if it is not good with these materials, it is not good with concrete, the absorption being just as great. | Moral. —Hollow walls for dry houses and machine-pressed concrete blocks are best and cheapest when taken in conjunotion with what is saved in plastercovering and the facility it gives to designing and planning. In c?ld climates, air space blocks are set in the middle of the walls. If this is not done, it is essential that all solid concrete exterior walls should be furred, lathed and plastered on the inside.