The mortar between bricks may break away and become uneven - this leaves the brickwork more porous as water collects in the damaged joints. The visible edge is called pointing and keeps a wall both weather-resistant and attractive. If pointing is necessary, use a narrow cold chisel and a club hammer to chop out the old pointing to a depth of about 10mm (2/5 inch). Be careful not to damage the bricks and brush away any dust.
The mortar mixture can be made from a straight cement : fine sand mixture in the proportions of approximately 1: 6. If dry hydrate is added there is less tendency to shrink during setting and the mixture will be easy to work. The proportions are then cement : dry hydrate : fine sand in the ratio 1 : 1 : 6. There are mortar dyes available if you are trying to match an existing pointing colour. However, colours are difficult to match exactly and staining of the brickwork is possible due to smearing while working on an area.
Have the mixture ready, then wet the joints so that the bricks do not absorb too much moisture from the mortar. Use the edge of the trowel to press the mortar in, and leave it projecting a little from the bricks. This is a fairly time consuming job, so it is advisable to work on a section of wall at a time. Prepare the section and enough material to replace the joints in that section before moving on to another section.
When replacing pointing it is important to use the same style - especially as some are more suitable for harsh weather conditions. Therefore examine any adjoining undamaged pointing as there are different types of pointing which may be suitable:
Concave or hollow pointing
If concave or hollow pointing is required, fill the joint flush with the surface, then hollow out the joint. There is a shaped jointing tool available for this job, but it can be done with the rounded end of a rod or tube drawn along the wet mortar. Shape the vertical joints first and then make long, continuous joints along the horizontal.
The pointing may be level as in flush pointing, which is made by wiping over the finished pointing with the trowel or piece of rough cloth. It is a suitable finish for sections of wall containing second-hand bricks, which have lost the sharper edging required for a different style of pointing.
A similar finish to concave or hollow pointing, but a deeper non curved hollow finish. Raked pointing is unsuitable for exposed walls, because they are not angled to deflect rain. Rake out the old cement in the joints to a depth of 6mm (0.25inches). There is a shaped jointing tool available which can be used for this job, but it can be done with the rounded end of a rod or tube drawn along the wet mortar. Shape the vertical joints first and then make long, continuous joints along the horizontal.
‘V’ joint pointing
Another similar finish to concave or hollow pointing, but with a definite line in the middle of the joint, running parallel to the brickwork. This gives a particularly smart finish to new brickwork or red brick. The shape of this pointing allows rain water to be easily shed.
If weathered pointing is used, there is sloping outward from the upper brick to the one below. From its name it is suitable for all walls, especially those exposed to harsh weather conditions. Fill and shape the vertical joints first, then use the edge of the trowel to press in the upper edges. Use the trowel along the edge of the board to cut the lower edge straight. A strip of metal bent at the end is suitable for a smooth finish. There is also a tool available for this job called a frenchman. This looks like a knife with the tip bent over at 90°. When the mortar is almost dry, lightly brush it across its top to brush away any odd scraps of mortar - but keeping the brushing light enough to avoid damage to the pointing.
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