The best method of building a brick wall is to first lay the two outside courses by spreading the mortar with a trowel along the outer edge of the last course of brick to form a bed for the brick to be laid, and scraping a dab of mortar against the outer vertical angle of the last brick laid, and then pressing the brick to be laid into its place with a sliding motion, which forces the mortar to completely fill the joint.
Having continued the two outer courses of brick to an angle or opening, the space between the courses should be filled with a thick bed of soft mortar and the bricks pressed into this mortar with a downward diagonal motion, so as to press the mortar up into the joints. This method of laying is called "shoving." If the mortar is not too stiff, and is thrown into the wall with some force, it will completely fill the upper part of the joints, which are not filled by the shoving process. A brick wall laid up in this way will be very strong and difficult to break down. A very common method of laying the inside brick in a wall is to spread a bed of mortar and on this lay the dry brick. If the bricks are laid with open joints and thoroughly slushed up it makes very good work, but unless the men are carefully watched the joints do not get filled with mortar, and the wall will not be as strong as when the bricks are shoved.
Another method of laying the inside brick is to lay them dry on a bed of mortar, as described above, and then fill all the joints full of very thin mortar. This is called grouting, and, while it is condemned by many writers, the author knows from actual experience that when properly done it makes very strong work. No more water than is necessary to make the mortar fill all the joints should be used, and grouting should not be used in cold or freezing weather. Grouting is especially valuable when very porous bricks are used. (See Section 132.)
For inside walls that are to be plastered the mortar projecting from the joints is merely cut off flush with the trowel. For outside walls and inside walls, where the brick are left exposed, the joint should be "struck" as in Fig. 122. This is done with the point of the trowel, by holding the trowel obliquely. Fig. 123 is the easiest joint to make, and is the one generally made unless Fig. 122 is insisted on. For inside work it makes no particular difference which joint is used, but for outside work Fig. 122 is much more durable, as the water will not lodge in the joint and soak into the mortar, as will be the case when the joint is made as in Fig. 123.
When "struck joints" are desired they should always be specified, otherwise the brick mason may claim that he is not obliged to strike them.
B. Face Brick. - Face brick are usually laid in mortar made of lime putty and very fine sand, often colored with a mineral pigment.
(See Sections 104 and 148.) The joints should not exceed 3/16 of an inch, except in cases where a horizontal effect is desired, when the horizontal joints are made ¼ of an inch and the vertical joints as close as possible. For very fine work the joints are sometimes kept down to 1/8 of an inch. The joints should be carefully filled with mortar and either ruled at once with a small jointer or else raked out and left for pointing. In very particular work a straight-edge is held under the joint and the jointer drawn along on top of it, thus making a perfectly straight joint. This is called rulled work. In laying the soffits of arches and vaults with face brick the joint cannot be finished until the centre is removed, therefore the joint should not be quite filled with mortar, and must be raked out and pointed after the centre is removed
Many pressed brick and some handmade bricks have one or more depressions in the larger surfaces of the brick to give a better key to the mortar. When the depressions are only on one side of the brick that side should be uppermost.
When building of face brick a piece of brickwork at least 2 feet high and 2 feet 6 inches long should be built up in an out-of-the-way place as soon as the first lot of brick is delivered, as a sample piece, and all stone or terra cotta work should be made to conform absolutely to the brickwork.
Sorting. - Pressed brick, even from the same kiln, generally vary in size and shade, the darker brick often being 1/16 inch thinner than the lighter brick and also shorter. If, therefore, a perfectly uniform color is desired the bricks must be sorted into piles, so that each lot will be of the same shade, and each shade laid in the building by itself. The change between the different shades should occur, where possible, at a string course or at an angle in the building. Many architects, however, consider that a handsomer and brighter wall is secured by mixing the different shades, so that hardly two bricks of exactly the same shade will come together, although if the mixing is well done the general tone of the wall at a distance will be uniform. With colored bricks this haphazard method undoubtedly gives the most artistic and sparkling effect.
Circular Work. - For circular walls, faced with pressed brick, the bricks should be made of the same (or very nearly the same) curvature as the wall. Many pressed brick manufacturers carry circle brick of different curvatures in stock, and any curvature can be made to order.
When circle brick cannot be obtained straight bricks may be used for curvatures with a radius of 12 feet or over, and for lesser radii half brick or headers should be used.