The most common part of a building that usually requires new pointing after it’s been built is the chimney stack. Due to the adverse conditions put upon it, it’s not surprising that it requires re- pointing. Usually you will find that the old cement/mortar will come out fairly easy. A cavity wall tie is often used for this process when the bricks are hard, as no damage will occur to the arris (edge) of the brick. If the bricks are of a soft nature you could use a piece of wood cut down to the width of the joint. Failing this you could use a “plugging chisel” which is a tapered chisel and can be purchased from most building supplies.

PROCEDURE

Take out all the mortar/cement to a depth of no more than 15mm, ensuring you are wearing the appropriate P.P.E. (safety glasses. dust mask etc.) After all the mortar/cement has been taken out brush all the joints to make sure any loose material is removed. This also make sure the arrises are clean. Do not use a wire brush as this will damage the brick. Wash down the wall with clean water - stubborn patches or stains can be removed using a scrubbing brush. Allow the wall to dry out, if you don’t it will become difficult to point the wall and the bricks may get soiled with the mortar. Also the more water there is in the wall, the more shrinkage movement there may be when the wall dries out. If this happens (moisture trapped in the joints), the first sign of frost the moisture will freeze and will expand and the wall gets damaged.

MORTARS FOR POINTING

If the area to be pointed is built with hard bricks in exposed places, a mix of 2:1 is preferred. This is two parts sand to one part cement, not mixed to wet. For general brickwork a mix of 3:1 is preferred.

In Part 2 I will explain the procedure to carry out the pointing sequence.

- Richard James

 

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