Concrete Roofing Tiles

Progress, Volume XI, Issue 11, 1 July 1916, Page 679

Concrete Roofing Tiles

Now that the price of building materials is up so high, advantage will no doubt be taken where possible to utilize local productions. Concrete roofing tiles are a case in point. These are being made in Auckland, and if correctly, and carefully made good results are obtained with the use of the corrugated concrete tile.

The corrugated concrete roofing tile, has proved to be the best, and is now used very largely. Weight, imperviousness, colour, appearance, shape, durability, protection against fire and storm and rainthe advantages are all in favour of the concrete roofing tile, if you manufacture your tiles of the right materials and in the right way. ''Don't

mix too dry, and ‘ keep the freshly made tiles from draught and sun.” Do not mix too wet, for if you do, the concrete will run off the pallets or the tile will lose its shape, but add as much water to your mixture as you can. To keep the freshly made tiles from draught and sun is important, because . both tend to dry the tile, which is very thin, too quickly, and thus rob the concrete of the moisture which it absolutely requires for the perfect crystallization of the cement in it. This can, of course, be overcome by lightly sprinkling the tiles with water while still on the pallets, which generally improves them. The materials used for this manufacture should be clean, sharp sand or washed granite or stone dust, all passing through an eighth inch sieve. This should be mixed in a proportion of three to one—three parts of sand, etc., to one part of cement. Mix well, for you should always remember that the difference between a tile and a brick is like that between a wine glass and a thick plate glass. The best machines for concrete roofing tiles are the hand machines, on which a man can turn out one hundred and fifty to two hundred and fifty tiles per day, equal to about one hundred and ten to one hundred and forty super, feet of roofing.

After the pallet has been placed in the machine, the workman puts on it one shovelful of mixed material. He then tamps down and shapes the surface of the tile by means of a shaped bar. After the tile has been made the correct shape and a

smooth surface, the colour sprayer is moved over the surface of the tile, and by one quick movement an even layer of dry colour mixture is spread over the surface. This is rubbed into the surface by means of a shaped bar, which at the same time forms a kind of glaze on the tile. The man then releases the tile by pressing on the foot lever. The tile resting on the pallet is then placed on the rack to harden. The process may seem rather complicated, but it is not in reality, and labourers can do this work to perfection, with ordinary care. The "Colour Mixture" consists of ten parts cement with one part of special colour powder (dry) which can be bought in any shade, but should preferably have waterproofing qualities. Tiles made by this method retain their colour and do not fade, but improve with age.

To mix colour, (it is a dry powder) with cement by hand perfectly, is next to impossible. It is possible, but three men would not be able to mix sufficient for one tile-maker to use daily, while in a colour mixer one man in an hour can mix a quantity sufficient to keep a tile maker going for a week. This type of mill, has a number of turned steel rollers in the drum.

Two days after the tiles have been made they can be taken off the pallets and stacked. They should not be sent out or placed on the roof before they are six weeks old. This is important.

The tiles are fourteen and a half by nine inches (thickness three eighths of an inch), and one hundred and forty go to the square ten feet by ten feet. The weight is about seven hundredweight per square.

To make one thousand concrete roofing tiles requires one and a half cubic yards fresh water clean sharp sand, eleven and a half hundredweight cement, and quarter of a hundredweight special colouring.

We are indebted to the "Crown" Magazine for the above particulars.