Over time, weathering and decay causes deterioration in the joints between masonry. This allows water penetration which can cause significant damage. Repointing is the process of renewing the mortar joints between bricks or masonry.
Repointing will also enhance the external appearance of the building.
However, the most important mistake that is continually made by builders/property maintenance experts and some roofing contractors is to use modern sand/cement mortar which sets extremely hard and they use it to re-point on top of the existing lime mortar. The type of bricks & lime mortar that are often found together are nearly always found to have been re-pointed with modern mortars. Old buildings are nearly all of a lime mortar construction and allow for much more movement, thus allowing the brickwork and lime mortar to breathe.
Along comes your expert re-pointer & re-points using a modern mortar which sets hard. Due to expansion and contraction of the walls or building with continual daily temperature changes, the soft bricks & lime mortar will expand at a greater rate than the new hard pointing you’ve had done. This mistake causes either damage to bricks which is commonly known as ‘spalding‘ or flaking brickwork and your new pointing will literally fall off the wall.
You have been warned!
We aim to match up the colour of your existing lime mortar to that found at your home prior to carrying out any re-pointing works, so that it all blends in nicely.
Generally, the old mortar is removed with a diamond mortar raking blade to an approximate depth of 1 inch, then all loose particles are washed out of the joint which also wets the brick work down prior to re-pointing.
If this isn’t done, the old brick work will crack the new pointing works.