Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/512

Rh 462 BUILDING [BRICKWORK. Laying bricks. Mortar joints and beds. a gauge-mould or a ranging trammel, for every course, as it must be evident that the line cannot be applied to this in the manner just described. For every wall of more than one brick thick, two men should be employed at the same time, one outside and the other inside ; one man cannot do justice from one side even to a 14-inch wall. Bricks should not be merely laid; every brick should be rubbed and pressed down in such a manner as to force the mortar into the pores of the bricks, and so produce absolute adhesion. Moreover, to make brickwork as good and perfect as it may be, every brick should be made clamp, or even wet, before it is laid, especially in hot weather, otherwise it immediately absorbs the moisture of the mortar, and, its surface being covered with dry dust, and its pores full of air, no adhesion can take place ; but if the brick be damp, and the mortar moist, the dust is enveloped in the cementitious matter of the mortar, which also enters the pores of the brick, so that when the water evaporates their attachment is complete. To wet the bricks before they were carried to the scaffold would, by making them heavier, add materially to the labour of carrying ; in dry weather they would, moreover, become dry again before they could be used, and for the bricklayer to wet every brick himself would be an unnecessary waste of his time ; boys may therefore be advantageously em ployed to dip the bricks on the scaffold, and supply them in a damp state to the bricklayer s hand. A watering-pot with a fine rose to it should also be used to moisten the upper surface of the last laid course of bricks preparatory to strewing the mortar over it. In bricklaying with quick- setting cements all this is of even more importance ; in deed, unless the bricks to be set with cement are quite wet it will not attach itself to them at all. As mortar is a more yielding material, used in brick work merely for the purpose of making the detached por tions of the staple adhere, by filling up their interstices and excluding the air, and the object is to produce as unyielding and consistent a mass as possible, no more should be used than is sufficient to produce the desired result. No two bricks should be allowed to touch, because of their inaptitude to adhere to each other ; and no space between them should be left unoccupied by mortar which may produce adhesion. When the bricks are a fraction under 2J inches thick, four courses of bricks and mortar, or brickwork, are usually allowed 11 inches in height; and if they are fully that thickness, four courses are allowed 11 J inches. The result of thick beds of mortar between the bricks is, that the mortar is pressed out after the joint is drawn, on the outside, in front ; and being made convex instead of slightly concave, the joints catch every drop of rain that may trickle down the face of the wall, and are thus saturated ; the moisture freezes, and in thawing bursts the mortar, which crumbles away, and creates the necessity, which is constantly recurring, of pointing the joints to preserve the wall. The diagram, fig. G, shows the section of a 9-inch wall, with the joints on the side a as drawn, and on the side b as bulged, in consequence of the quantity of mortar in them yielding to the weight above. This, too, is in addition to the inconvenient settling, which is the con sequence of using too much mortar in the beds. In practice, bricklayers lay the mortar on the course last finished, and spread it over the surface with the trowel, considering that it will fill the space between the bricks of that course, in addition to what they may have placed in the edges of the outside joints; but the mortar ought not to be so thin as to fall into the joints by its own weight; so, unless they press it down, half the height of the space between the bricks remains unoccupied, and the wall is consequently hollow, incompact, and necessarily imperfect. To obviate this, it is common to have thick walls grouted in every third or fourth course ; that is, Grouting mortar made liquid, and called grout, is poured on and spread over the surface of the bricks, that it may run in and fill up tho joints completely. This, at the best, is but doing with grout what should be done with mortar ; and filling or flushing up every course with mortar requires very little additional exertion, and is far preferable. It also assists in making the house warmer and drier, by preventing the passage of wind or damp through the joints. All the walls of a building that are to sustain the same Walls tc floors and the same roof should be carried on simultaneously ; be carrie under no circumstances should more be done in one part U P to ~ than can be reached from the same scaffold, until all the ge walls are brought up to the same height, and the ends of the part first built should be racked back, as at a b, Plate XX. fig. 2, and not carried up vertically with merely the toothing necessary for the bond, as at a b, fig. 3. Brickwork should never be carried on in frosty weather, Frost. nor even when it is likely that frost will occur before the walls can be covered in or become so dry as not to bo affected by frost. Covering an unfinished wall with a thick layer of straw when frost may supervene is a very useful precaution ; and on the straw weather-boarding should be laid, to prevent access of moisture from rain or snow. Merely wet weather may be guarded against by following the directions given above as to flushing every course of the work well up with mortar, so that no interstices be left into which water may insinuate itself, and by covering the walls with boards to act as a coping when the men are not actually at work on them : the joints in the face of a wall that is not to be plastered in any way should be pro tected in this manner with great care. After the footings of a wall (above noticed) have been Damp- brought up to the level of the finished surface of the P roof ground, or to the underside of the joists of the lowest floor, course&amp;gt; there should always be introduced a damp-proof course, intended to prevent that rise of damp from the soil in the brickwork which is the cause of so much disfigurement and injury to buildings. This damp course is formed in various ways, as a layer of asphalt, or asphalt canvas, or some similar material. One of the best and most usual, as the materials are always at hand, is formed of two courses of slates, well break ing joint, and set in cement. Another is Taylor s or Jcn- nings s patent stoneware damp course, which being pierced horizontally admits air to the space under the floor and thus ventilates it. Where the ground would come against the walls of a basement story, it is requisite, in order to keep them dry, either to form an open drain or area, or to make what is called a dry area. This is done by building up against the soil a thin wall of brick work not less than 8 inches from the main wall, and either Dry are Fig. 7. straight or curved, and covering it over above the ground with stone or slate, as in fig. 7. Thus any water coming through the thinner wall falls down, and is conveyed away or soaks through the bottom. This thinner wall requires