Now that we have considered bricks and partly considered mortar, it remains to pay some attention to brickwork. The simplest and most familiar work for a bricklayer to do is to build a wall. In doing this his object should be to make it as stout as possible for the thickness, and this stoutness can only be obtained by interlacing the bricks. If they were simply laid on the top of each other, the wall would be no more than a row of disconnected piles of bricks liable to tumble down. When the whole is so adjusted that throughout the entire wall the joints in one course shall rest on solid bricks and shall be covered by solid bricks again--in short, when the whole shall break joint--then this wall is said to be properly bonded, and has as much stability given to it as it can possibly possess. There are two systems of bonding in use in London, know as English bond and Flemish bond. English bond is the method which we find followed in ancient brickwork in this country.
In this system a course of bricks is laid across the wall, showing their heads at the surface, hence called "headers," and next above comes a course of bricks stretching lengthways at the wall, called stretchers, and so on alternately. With the Dutch fashions came in Flemish bond, in which, in each course, a header and a stretcher alternate. In either case, at the corners, a quarter-brick called a closer has to be used in each alternate course to complete the breaking joint. There is not much to choose between these methods where the walls are only one brick thick. But where they are thicker the English has a decided advantage, for in walls built in Flemish bond of one and a half brick thickness or more there must be a few broken bricks, or bats, and there is a strong temptation to make use of many. If this takes place, the wall is unsound.
Many of the failures of brickwork in London houses arise from the external walls, where they are 1½ bricks thick, being virtually in two skins; the inner 9 in. does the whole of the work of supporting floors and roof, and when it begins to fail, the outer face bulges off like a large blister. I have known cases where this had occurred, and where there was no header brick for yards, so that one could pass a 5 ft. rod into the space between the two skins and turn it about. This is rather less easy to accomplish with English bond, and there are other advantages in the use of that bond which make it decidedly preferable, and it is now coming back into very general use. There are some odd varieties of bond, such as garden bond and chimney bond. But of these I only wish to draw your attention to what is called cross bond. The name is not quite a happy one. Diagonal bond is hardly better. The thing itself is to be often met with on the Continent, and it is almost unknown here. But it would be worth introducing, as the effect of it is very good.
French cross bond, otherwise diagonal bond (liaison en croix), is English bond, but with the peculiarity that in every fourth course one header is made use of in the stretcher course at the quoin. The result is that the stretchers break joint with each other, and all the joints range themselves in diagonal lines, and if in any part of the work headers of a different brick are introduced, the appearance of a cross is at once brought out; and even without this the diagonal arrangement of joints is very perceptible and pleasing.
Besides wall building, the bricklayer has many other works to perform. He has to form fireplaces, flues, chimneys, and the flat trimmer arches which support the hearth, and has to set the stove, kitchen range, copper, etc., in a proper manner. He has to form various ornamental features and much else, some of which we shall have an opportunity of noticing rather later. The strangest business, however, which is intrusted to the bricklayer is building downward--by the method known as underpinning--so that if a foundation has failed, a sounder one at a greater depth may be reached; or if a basement is required under an existing building which has none, the space may be excavated and the new walls built so as to maintain the old.
This work has to be done with great caution, and bit by bit, and is usually left to experienced hands. The mode in which the mortar joints of a brick wall are finished where they show on the external or internal face is a matter worth a moment's attention. It is important that the joints of the work shall be so finished as to keep out wet and to be as durable as possible, and it is desirable that they should improve, or at any rate not disfigure, the appearance of the work.
The method which architects strongly advocate is that the joints shall be struck as the work proceeds--that is, that very shortly after a brick is laid, and while the mortar is yet soft, the bricklayer shall draw his trowel, or a tool made for the purpose, across it, to give it a smooth and a sloping surface. This is best when the joint is what is called a weather joint--i.e., one in which the joint slopes outward. Sloping it inward is not good, as it lets in wet; finishing it with a hollow on the face is often practiced, and is not bad. Bricklayers, however, most of them prefer that the mortar joints should be raked out and pointed--that is to say, an inch or an inch and a half of the mortar next the outer face be scratched out and replaced with fresh mortar, and finished to a line.
In cases where the brickwork is exposed to frost, this proceeding cannot be avoided, because the frost damages the external mortar of the joints. But the bricklayers prefer it at all seasons of the year, partly because brickwork is more quickly done if joints are not struck at the time; partly because they can, if they like, wash the whole surface of the work with ocher, or other color, to improve the tint; and partly because, whether the washing is done or not, it smartens up the appearance of the work. The misfortune is that this pointing, instead of being the edge of the same mortar that goes right through, is only the edge of a narrow strip, and does not hold on to the old undisturbed mortar, and so is far less sound, and far more liable to decay. There is a system of improving the appearance of old, decayed work by raking out and filling up the joint, and then making a narrow mortar joint in the middle of this filling in, and projecting from the face. This is called tuck pointing. It is very specious, but it is not sound work.