Plumbing Brickwork

The ends or corners of brick walls must be built vertically upright, or ‘plumb’ on their face sides, and this is also checked by using a spirit level. Accurately ‘plumbing up’ the ends or corners is key to the basic principle of constructing walling. Having established fixed, vertical end points it is then possible to ‘run-in’ the brickwork to a spirit level or string-line (depending on the wall length), thus ensuring that the whole face plane of the wall is vertically aligned.

The acceptable industrial tolerance for plumb is + or – 3mm in 1.0 m height. Whilst brickwork may be generally vertical throughout its overall height, this is not enough on its own. Brickwork can still fail to meet the accepted tolerance for plumb because individual bricks or groups of bricks might be indented or bowed inwards by more than 3mm. Alternatively, individual bricks or groups of bricks might project or bow out by more than 3mm (see Fig 128).

Plumbing Brickwork

Fig. 128 Common defects when plumbing brickwork.

One of the key elements of successful plumbing up of brickwork is to spend plenty of time getting the first three courses of any new corner or wall end absolutely spot on for plumb. The positioning of the bricks in relation to the level is best examined when down on one knee. Any errors must be corrected as close to perfection as the materials will allow. Plumbing any subsequent courses is thus made easier, since the level can be ‘clamped’ with the foot against the first three courses and every new course above simply adjusted until it aligns with the level. In this way, the first three courses become a ‘datum’ for plumbing and this helps eliminate unacceptable dips, bumps and hollows in the vertical alignment.

Plumbing Brickwork

Fig. 129 It is important to spend enough time getting the first three courses spot on for plumb.

A spirit level’s bubble will indicate whether the surface plane is generally vertical (or horizontal), but a spirit level is more than just an air bubble inside a tube of liquid; it is also an invaluable straight-edge for measuring the line, flatness and face plane of brickwork. Both features together provide a bricklayer with vital information about how bricks are positioned and the extent and direction of any adjustment that may be needed. Tell-tale gaps between the brick face and the edge of the level offer useful clues. A tapering gap (see Fig 130) tells the bricklayer that the quoin brick needs adjustment by tapping the top of the brick at the front edge in order to bring the top of the face into vertical alignment with the level. When bricks require adjusting sideways to achieve plumb, the face of the brick should not be tapped with the edge of the trowel blade as this can damage or mark the face!

Plumbing Brickwork

Fig. 130 A ligning the quoin brick to plumb. BUILDING CORNERS

The skills of gauging, levelling and plumbing brickwork need to be brought together for the purposes of building corners or ‘quoins’, and exactly the same principles apply to constructing the stopped-ends of wall. Accuracy for gauge, level and plumb is absolutely vital when constructing the corners or ends of walling, as any mistakes or inaccuracies will be transferred to, and replicated in, the middle section of the wall when it is run-in in between.