Laying Th Brick

612.

The brick should be laid in a truly horizontal position. Masons are apt to lay brick with the back edge higher than the front, so as to tip the top edge of the front face out a little and thus give a projecting edge upon which to rest the trowel while finishing the joint (see 5 613). If the brick are laid in this way, the wall has a rough irregular appearance. This defect is more common with pressed than with common brick, since with the latter it is not customary to attempt to finish the joint except to knock off any projecting mortar.

The top edge of the face should be laid to a stretched string. The joints should be kept of uniform thickness throughout. The horizontal joints should be truly horizontal. Care should be taken to preserve the bond.

Pointing.

In laying inside walls that are to be plastered, the mortar that is forced out when the brick is pressed into position is merely cut off with the trowel; but for out side walls and also for inside walls that are to be left exposed, the joints should be more carefully finished. In laying common brick the mortar in the vertical joints is simply pressed back with the flat face of the trowel; but there are three methods of pointing or finishing the bed joints, viz.: (1) flush joints, (2) struck joints, and (3) weather joints.

Flush pointing consists in pressing the mortar flat with the trowel, thus making the edge of the joint flush with the face of the wall—see The struck joint is formed by resting the lower edge of the blade of the trowel upon the edge of the brick below the joint and drawing the trowel along the joint, which smoothes the face of the joint and slightly consolidates the mortar, and leaves the joint as shown in the center of Fig. 77.

The weather joint is formed, as shown in right-hand side of Fig. 77, by pressing the mortar back with the upper edge of the trowel. This form of finish is much more durable than the struck joint, since water will not lodge in the joint and soak into the mortar, and on freezing dislodge the mortar; but this form of joint is much more difficult to make, since the mason stands above and back of the brick he is laying. If the weather joint is desired, it must be dis tinctly specified and the inspector must be watchful to see that it is secured.

Brick masonry is usually laid with lime mortar or with lime cement mortar, the lime giving cohesive strength to the mortar so that enough mortar stays in the joint to permit of its being success fully struck; but when cement mortar or mortar containing but little lime is used, the mortar is so lacking in cohesion that enough does not remain in the joint to permit of striking it, and hence with cement mortar it is necessary to formally point the masonry. For

description of methods of pointing applicable to brick masonry, see § 565.

Pressed brick are usually laid with a mortar made of one volume of stiff lime paste (called lime putty) and one volume of fine sand; and when this mortar is used, the brick is buttered, i.e., a little mortar is spread upon only the edges of the brick before it is laid. If the above mortar were spread over the entire surface of the brick, the joint could not be made as thin as is usually specified; but some of the better architects specify thicker joints for pressed work so that the bricks can be laid otherwise than by being buttered. If the mortar is to be spread in the usual way, it should consist of 1 volume of lime paste to about 2 volumes of rather fine sand. Some architects specify 1 volume lime paste, 1 volume natural cement, and 2 volumes of fine sand. Some contractors prefer to substitute at their own expense a rich natural-cement mortar and lay thicker joints rather than lay thin buttered joints, since the brick mason can lay more brick with the former than with the latter.

The joints of pressed-brick work are finished by grooving or beading (see Fig. 74, page 287), the former more common. The grooved joint is preferred to the flush joint, because of the variation in light and shade that the former gives to the face of a wall.

A brick wall whose top surface is to be exposed to the weather should be finished with some protective covering to pre vent water from penetrating to the interior of the wall. This covering may consist of a layer of lime or cement mortar, or a coping of stone or vitrified clay. The latter is made with a crowned upper surface, over-lapping joints, and a lip to project downward past the face of the wall.

IMPROVZMZNrs IN BRICKLAYING. The methods of bricklay ing in common use at present are substantially the same as those em ployed from time immemorial, with the exception of the compara tively recent modification of the so-called English bond by using one course of headers to each five or six courses of stretchers instead of alternate courses of headers and stretchers; but very recently three innovations have been proposed which seem to be important improve ments in the methods of laying brick. These innovations are: 1. The packet system of handling the brick from the car or wagon to the wall. 2. A special scaffold for holding the packets of brick within easy reach of the mason. 3. A fountain trowel which facili tates the spreading of the mortar.