PRINCIPLES OF RUNNING-IN BETWEEN CORNERS
The method of running-in is dictated by the length of the wall. On short walls or piers, running-in of each course can be achieved using a spirit level. The end or corner brick (‘quoin brick’) is first laid to gauge, plumb and level. The end or corner brick can then be laid level and plumb at the other end, with level transferred from the first brick by way of a spirit level. Level is achieved for the brickwork in between simply by using the spirit level as a straight-edge and tapping the bricks down until the ends of the level touch the bricks at each end. Achieving the correct face line is done in the same way, but using the level on the face of each course between the two plumbing points and adjusting the face of each brick until it touches the level at its top edge and its bottom edge is flush with the course below.
Where the length of the wall exceeds the length of the level, both ends of the wall need to be built independently, with horizontal level from one end to the other being achieved using a spirit level and straight-edge. Where walls are of such a length that the use of the straight-edge becomes impractical for transferring levels, then a datum level must be transferred to each end or corner of the wall in order that the ends can be built independently but still to the same level. This is achieved by applying the methods used in Chapter 6.
For all walling that exceeds the length of a spirit level, a string-line must be used for running-in, to ensure accurate and straight alignment of brickwork in between the two ends. Bricks are laid so that the top edge almost, but not quite, touches the line, to avoid pushing the line out, and the bottom edge is flush with the course below. Pushing the line out will result in the brickwork running out of line and a bow forming in the face of the wall.
Running-in, particularly to a line, can be thought of as ‘placing the face’ of the brick between two upper and lower fixed points – the string-line and the top of the course below. When laying bricks and scraping off mortar that squeezes from the bed joint, it is possible to ‘feel’ with the trowel blade whether the bottom edge of the brick is flush with the course below. If the bed joints are spread too thickly, time and effort will be wasted in having to tap bricks down to the line. The ideal is for the mortar to be spread sufficiently thickly so that the brick can be pressed by hand to the line without any need for tapping, yet still achieving a full bed joint. As before, adjustments should not be made to the brick by tapping the face with the edge of the trowel blade; this can mark and damage the decorative face side.