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Roofing-Tiles. 1⁄4 261⁄2 – 30

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Tiles are thin slabs of baked clay. They are extensively used in Europe for roofs, gutters, and house-siding, and, to some extent, in this country.

Plain roofing-tiles are usually made of an inch in thickness, 101⁄2 inches long, and 6 inches wide. They weigh from 2 to 2 pounds each, and expose about one-half to the weather. 740 tiles cover 100 superficial fect. They are hung upon the lath by two oak pins inserted into holes made by the moulder. Plain tiles are now made with grooves and fillets on the edges, so that they are laid without overlapping very far, the grooves leading the water. This is economical of tiles, and saves half of the weight, but is subject to leak in drifting rains, and to injury by hard frosts.

Pan-tiles, first used in Flanders, have a wavy surface, lapping under, and being overlapped by, the adjacent tiles of the same rank. They are made 14 by 10, expose ten inches to the weather, and weigh from 5 to 5 pounds each. 170 cover 100 square feet of surface.

Crown, ridge, hip, and valley tiles are semi-cylindrical, or segments of cylinders, used for the purposes indicated. A gutter-tile has been introduced in England, forming the lower course, being nailed to the lower sheathing-board or lath.

Siding-tiles are used as a substitute for weather-boarding. Holes are made in them when moulding, and they are secured to the lath by flat-headed nails. The gage, or exposed face, is sometimes indented to represent courses of brick. Fine mortar is introduced between them when they rest upon each other. Siding-tiles are sometimes called "weather-tiles" and "mathematical tiles." These names are derived from their exposure or markings. They are variously formed, having curved or crenated edges, and various ornaments, either raised or encaustic.

The unglazed tiles are inferior to slate, as they imbibe about oneseventh of their weight of water, and tend to rot the lath on which they are laid. Good roofing-slate only imbibes one two-hundredth part of its weight, and is nearly waterproof.

Tin Roofs.

[Revised for Fourth Edition.]

A tin roof of good material, properly put on, and kept properly painted, will last from thirty to forty years. It should not be painted for the first time until it has been well washed by rain, to get the grease off the tin; and all rosin, if used, should be carefully scraped off. One or more layers of felt-paper should be placed

under the tin, to serve as a cushion, and also to deaden the noise produced by the rain striking the tin.

For a steep roof, the tin should be put on with a standing groove, and with the cross seams double-locked and soldered. A very common and cheaper method for steep roof is, to double-lock both the vertical and cross seams, and fill the joint with white lead instead of soldering; but the other method is much the best. For flat roofs, the tin should be locked and soldered at all joints, and secured by tin cleats, and not by driving the nails through the tin itself.

In soldering the joints, rosin as a flux is generally preferred; although some roofers recommend the use of diluted chloride of zinc.

Roofing-plates are made of steel or iron, and covered with a mixture of lead and tin, and are designated as "tern," "leaded,” or "roofing tin," in distinction from plates coated only with tin, and therefore called "bright tin." Roofing-plates are coated by two methods. The original manner of coating the plates was by dipping the black plate into the mixture of tin and lead, and allowing the sheets to absorb all the coating that was possible; and several brands of roofing-tin are still made by this process. The other process, by which the majority of roofing-plates are now made, is known as the "Patent-roller Process," by which the plates are put into a bath of tin and lead, and are passed through rolls, the pressure of which leaves on the iron or steel a thickness of coating which, to a great extent, determines the value of the plate. These rolls can be so adjusted as to leave a good amount of coating on the plate, an ordinary coating, or a very scant one; the heavier the coating, the more valuable the plate.

There have been only two sizes of roofing-plates made for a number of years; namely, 14 × 20 and 20 × 28: and of these two sizes, the larger is more generally used, from the fact that, being double the size of the smaller plate, it requires less seams on the roof, and consequently cheapens the cost of putting on.

Besides these two sizes, there is another size, 10 × 20, which is used for gutters and leader-pipe. A better roof will be obtained by using the 14 × 20 than the 20 × 28, because the seams are closer together, thus making the roof stronger; and, if put on with a standing seam, there is more allowance for expansion and contraetion.

For steep roofs with standing groove, the tin should be laid with the smallest dimension for the width; as it makes the roof stronger, and allows a greater amount of expansion and contraction. Unfortunately, it is much cheaper to lay them the other way, as less

cleats, solder, nails, and labor are required. Hence the architect should always specify in what way the sheets are to be laid. For a flat roof with flat seams, it does not make any difference which way the plates are laid, as the entire roof is practically a solid sheet.

There are two thicknesses of roofing-plates: namely, IC, or No. 29 gauge, which represents a weight of eight ounces to the square foot; and IX, or No. 27 gauge, which represents a weight of ten ounces to the square foot. The IC plates are far more extensively used than the IX, because they are less expensive; and as the question of cheapness has more or less bearing on the subject of tin roofs, the IC has therefore been given the larger preference. But at the same time it should not be forgotten, that, for the extra cost of a box of IX over IC, there is an excess of weight given over that on an IC plate of two ounces per square foot; and this is fully worth the difference in price.

The value of one brand of roofing-plates as against another brand is dependent on five things: 1st, the quality of the material of which the plate is made; 2a, the coating, or the thickness of the tin and lead that is upon the plate, and which can only be determined by trying with a knife; 3d, the net weight of the hundred and twelve sheets in the box; 4th, the squareness of the sheets; 5th, assortment of the sheets. It is impossible to determine the value of any brand by the sample sheets; in fact, all plates are rolled hot, in packs of eight sheets each. The two outside sheets cooling more rapidly than the six inside sheets, the latter are always slightly thinner; consequently there are twentyeight sheets in every box heavier than the other eighty-four. As thousands of sheets are rolled at a time, then tinned, and indiscriminately packed, there is lawfully a slight difference in weight of the different boxes of the same brand, while there is a greater difference between the weights of the boxes of different brands. The standard weight of an ordinary IC plate, 14 × 20 size, is 108 pounds to the hundred and twelve sheets; while there are many boxes imported of IC 14 × 20 that run all the way from 90 to 120 pounds in weight. The standard weight of a box of IX 14 × 20 18 136 pounds; or IX 20 × 28, 272 pounds. There are IX 14 × 20 plates imported that do not weigh over 120 pounds per box, while others weigh as much as 150 pounds for the same size. It may be, that the lighter sheets have as heavy a coating of lead and tin as the heavier sheets; but the probability is, that they have not. All roofing-plates were formerly made of coke or charcoal iron, while now they are made of either Martin Siemen's or the Bessemer steel. Of these two makes, the former can always be depended

-upon as a perfectly reliable article; while this cannot at all times be said of the latter.

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In all tin roofs, whether the main body of the roof is made of ordinary rolled or dipped plates, the gutters, flashings, etc., should be made of the heaviest coated or dipped plates, and should always be of IX thickness. In the manufacture of all roofing-plates, there arise imperfect sheets, having corners and edges broken, spots uncovered with tin, etc. These are packed by themselves in separated boxes, and denominated as wasters;" while the perfect sheets are denominated "prime" plates. The boxes containing "wasters," or imperfect sheets, are marked "ICW," or "IXW," according to the thickness; so that, where the letter "W" appears on a box, it shows that the box contains imperfect sheets, and should not be accepted when "prime" tin is specified. To make sure of obtaining the best tin in the market, and getting the article specified for, the architect should specify that "every sheet be stamped with the name of the brand and thickness" (IC or IX, as the case may be), as all the best plates are now coming out with every sheet stamped.

In this way only can the architect or owner be sure that he is getting what the specifications call for; and it also protects the honest contractor against those who estimate with the intention of using a cheaper article.

An excellent paint for tin roofs is composed of 10 pounds Venetian red, pound red lead, 1 gallon pure linseed oil.

The tin should be painted again at the end of the first year, and once in four years afterwards.

HYDRAULICS OF PLUMBING.

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The following pages on the hydraulics of plumbing are, with the consent of the author, taken directly from the fifth edition (1884) of an excellent work on House-Drainage and Water-Service,"1 by James C. Bayles, Esq., editor of The Iron Age" and "The MetalWorker."

Water is practically an incompressible liquid, weighing, at the average temperature of sixty degrees F., about 62.3 pounds to the cubic foot, and 8.3 pounds to the gallon. These figures are subject to slight variations incident to changes in temperature.

A column of water twelve inches high exerts a downward pressure of about 0.43 of a pound to the square inch.

A columm two

Published by David Wilhams, 83 Reade Street, New York. The author recommends this work to architects and plumbers as a thorough and able trea tise on the plumbing of city and country houses.

feet high exerts a pressure of about 0.86 of a pound, or just twice that exerted by a column one foot high. This pressure per square inch, due to head, is irrespective of volume, or any thing else except vertical height of column. With these figures in mind, the calculation of the pressure per square inch due to any head is a simple matter. The following rules will be found valuable for reference:

TO FIND PRESSURE IN POUNDS PER SQUARE INCH EXERTED BY A COLUMN OF WATER. - Multiply the height of the columni, in feet, by 0.43.

TO FIND THE HEAD. - Multiply the pressure, in pounds per square inch, by 2.31.

Pressure of Water.-The weight of water or of other liquids is as the quantity, but the pressure exerted is as the vertical height.

Fluids press equally in all directions: hence any vessel or conduit containing a fluid sustains a pressure on the bottom equal to as many times the weight of the column of greatest height of that fluid as the area of the vessel is to the sectional area of the column.

Lateral Pressure. The lateral pressure of a fluid on the sides of the vessel or conduit in which it is contained is equal to the product of the length multiplied by half the square of the depth and by the weight of the fluid in cubic unit of dimensions. The following formula is simple and satisfactory: multiply the submerged area in inches by the pressure due to one-half the depth. By submerged area" is meant the surface upon which the water presses; for example, to find the lateral pressure upon the sides of a tank twelve feet long by twelve feet deep: 144 × 144 = 20736 inches of side. The pressure at the bottom will be 12 × 0.43 = 5.16 pounds, while the pressure at the top is 0, giving us, say, 2.6 pounds as the average: therefore 20736 × 2.6 = 53914 pounds.

Discharge of Water. The quantity of water discharged during a given time from a given orifice, under different heads, is nearly as the square roots of the corresponding heights of the water in the reservoir or containing vessel above the surface of the orifice.

Small orifices, on account of friction, discharge proportionately less than those which are larger and of the same shape under the same pressure.

Circular apertures are the most efficacious, having less surface in proportion to area than any other form.

If a cylindrical horizontal tube through which water is discharged

A head of water equals the height that the water rises above the orifice.

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