Practical hints to builders and those contemplating building / Facts worth considering relating to foundation, cellar, kitchen, chimney, cistern, brick-work, mortar, heating, ventilation, the roof, and many items of interest to builders.

by National Sheet Metal Roofing Co.

WHAT IS GOOD MORTAR?

To a casual observer mortar is mud, but to a builder who understands the chemistry of mortar it is a compound of water, lime and sand, and when properly prepared forms an indestructible cement. Fresh slacked lime, when brought in contact with clean, sharp sand, adheres strongly to the surface of each grain, and forms the silicate of lime.

At the same time the drying mortar absorbs carbonic acid from the atmosphere, forming with it lime-stone, which in time becomes a rock in solidity. Now, all mortar is good or bad in proportion to the purity of the ingredients and their relative affinity for each other. The adhesive properties of mortar are nullified by loam or clay in sand, or the stale condition of lime used.

Loam mortar adheres freely to the surface of walls or ceilings. So does mud if thrown against an upright surface; but water dissolves it. It dries quickly, but does not harden with age. The foundation of many frame, and the entire walls of many brick houses are built with poor mortar, when the materials for good could be had at the same price.

Water, lime, sand and hair are the ingredients for plasterers’ mortar in about the following proportions: One bushel unslacked lime and four bushels sharp sand; (to this add twenty-four pounds of dry hair for every one hundred yards, when used for “scratch” or first coat,) and water sufficient to make it of proper consistency. After being properly mixed, the mortar should stand from three to ten days before using. However, the time it should stand depends upon the susceptibility of the lime to slack. Some lime requires a month, while good lime slacks immediately. Age improves mortar, provided it is kept wet, and makes it work easier under the workman’s trowel. As it is the keys formed by pressing the mortar against the lathing on the ceiling that holds it to its place, there should be a relative width of lath and key space to insure strength sufficient to prevent its falling. Ignorance of this, and poor mortar, is the cause of falling ceilings. Lath one inch wide, 7/16 inches thick, placed 7/16 inches apart will insure good strong work.

The second coat needs but a very small quantity of hair. Fifty bushels sand, and twelve and one-half bushels unslacked lime, will make mortar enough to cover one hundred square yards. If mortar freezes before it is dry it loses its cementing properties and becomes in common phase rotten, but if the sand used is clean, and it remains frozen without thawing until it is dry, it is not injured. The best way to treat a house in which the plastering is not dry, and cannot be kept from freezing before it dries, is to throw the house open, and let it freeze for eight or ten days, or until the plastering freezes dry.

Cisterns should be plastered inside with mortar made of equal parts of hydraulic lime and clean sand. For brick work above foundations use one part unslacked lime to four parts sand.

“THE INDEPENDENT,” 251 Broadway, New York, October 28th, 1889.

Gentlemen:—The shingles from your respected concern used on my new house look splendidly, and give entire satisfaction. They are far better than any metal shingles I have previously used on other buildings, which I have had torn off and thrown away as worthless. At times we were flooded by the water under their (want of) protection, and we could not stop the leaks. Noah in the ark I am sure was, fortunately, not troubled with leaks such as we endured for years; if he had been all would have been drowned. Now, under your protection, we are all right and still alive.

Faithfully,

HENRY C. BOWEN,
Chandler.