This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol1", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
In jointing, the mortar in which the bricks are bedded is simply trimmed up as the work proceeds, as shown at A, G, Fig. 186.
This is formed by pressing the soft mortar, which oozes from the joints when a brick is bedded, flush against the wall with a trowel, as shown at A.
This joint, shown at B, is formed as a Flat Joint, and an indent is made along the centre of both the vertical and horizontal joints by means of a Jointer (Fig. 174) run along a straight edge or Jointing rule, as it is called when used for this purpose. Any strip of iron with a smooth edge may be used as a jointer.
In this the horizontal joints are formed, as shown at C and D, by pressing or striking one edge back from the surface of the wall with a trowel. The vertical joints are usually made flat. The joint shown at C is a very good one, as the sharp line of shadow which it produces gives a pleasing effect, while at the same time it throws all rain water away from the joint. The joint shown at D is, on the contrary, a bad one, as it enables the water to lodge on the upper edges of the bricks. This freezes in winter, breaking away the edge, while in warm weather it soaks into the joints and causes the wall to be damp.
This joint has rather a pleasing effect when used in low walls built of regularly shaped bricks of a non-porous nature, owing to the sharp line formed by the upper edges of the brick, but this effect is lost at a height of a few feet above the eye level.
When brickwork is built of non-absorbent bricks a pleasing effect can be produced by recessing the mortar joint back from the surface of the wall, as shown at E.
This joint, shown at F, is formed by pressing the mortar back from the surface with a jointer of the width of the joint, having its edge moulded. Mason's V-Joint. - This form of joint, which is shown at G, derives its name from its constant use for finishing the mortar joints of stone masonry.
In Pointing, the joints are raked out with a tool called a Raker (Fig. 174) to a depth of at least 1/2 inch as the work proceeds, and then, filled with mortar stopping, starting with the top joints and working downwards as the scaffold is removed. The pointing is worked on the face of the wall in any of the methods shown at A, B, C, D, E, F, and G in Fig. 186, a pointed weather-struck joint being shown at J.
Tuck Pointing is the term applied to the operation of stopping the joints flush with cement or hard mortar, and running a fine line of white lime putty upon it, as shown at H.
After the stopping has been filled in the whole of the face of the work is coloured to the desired tint with a mixture of copperas (sulphate of iron) and a colouring pigment; or else the face of the brickwork is rubbed over with a piece of brick until the joints are the same colour as the bricks. Lime putty, composed of equal parts of lime and fine sand, with the addition of a little plaster of Paris, is forced on to the mortar joint with a jointer worked along a straight edge. The edge of the putty lime is trimmed with a knife with the end turned up at right angles, and known as a Frenchman (see Fig. 174), the putty being cut by the edge of this knife, and the superfluous material being scraped away by the turned up end. The putty line, when finished, should project about 1/16 inch from the surface of the wall.
Its thickness is a matter of taste, but it is usually 1/4- inch or less. Tuck pointing when carefully done is more than twice as expensive as ordinary pointing, but when roughly done it is frequently used as a cloak to hide excessively large mortar joints or other careless workmanship. It is frequently used to improve the appearance of brickwork in which the edges of the bricks have been destroyed by frost, but in no case can it be regarded as satisfactory, as the lime putty is slightly soluble, and is soon destroyed by heavy rains or discoloured by a smoky atmosphere.
This is the name given to a kind of pointing in which a projecting line of mortar is formed upon the stopping itself, as shown at I.
When brickwork is to be covered with plaster the joints are formed with the mortar projecting as at K, or they are raked out as shown at L so as to form a key.
Suppose it is required to set out the building shown in Fig. 187. One corner of the wall, such as A, is fixed absolutely by measurement from surrounding objects shown on the plan, and a peg is driven into the ground, and a nail driven into the peg to mark the exact spot where the angle occurs. The point B is now determined by measurement from surrounding' objects (or the direction AB is set out with regard to the magnetic north, and the distance AB is carefully measured), and another peg is driven in at B. A line is stretched from A to B, and is used as a base line from which to set out the rest of the work. The line AE is now set out by measurements from A and B taken off the plan. The sum of these distances is marked on a piece of well-stretched cord. One end is held or tied at A and the other at B, a knot having been made at E (at the correct distance from A). Taking this knot in the hand, the string is tightened, and the point E is fixed accurately and a peg is driven into the ground at E. In a similar manner the points C, D, F, and G are pegged out. Angles are sometimes set out by means of wooden templates, and right angles may be set out by means of a tape held out into the form of a right-angle triangle, the sides being in the proportion of 3, 4, 5. The bow may be set out in two ways: - 1. The points H and J are fixed by measurement along FG; then K, the centre of the arc, is fixed by measurements from H and J; at K a stake is driven with its head just above the ground, and a strip of wood with a hole bored through one end is nailed loosely to the top of the stake, its nail being carefully placed so that its centre coincides with the centre of the arc to be set out. At the other end of the strip of wood marks are made corresponding with the thickness of the wall and the concrete foundations, as shown in Fig. 188.