Learn how to repoint brick walls. The natural action of wind and rain will cause mortar between the bricks of your house to loosen, crumble and wear down. This not only looks bad but can also allow water to penetrate the bricks. The answer to this problem is re-pointing. This is not a difficult job and you only need a few tools to carry it out. However if you need to re-point in large area, high up on a wall, it might be worth hiring scaffolding to make things easier.
Preparing the Joints
Use an old screwdriver or cold chisel to scrape out any loose mortar and a hammer and chisel to clear out any remaining pieces. Take the mortar back by about 15 millimetres from the face of the brick, and then use an old paintbrush to remove any dust from the gap. Brush the brickwork and joints with clean water to help stop moisture being absorbed out of the new mortar too quickly. If you don’t do this, you risk the mortar falling out of the gaps as it sets too quickly.
Repointing the Wall
The mortar should form a continuous band around the brick and be angled to allow moisture to run off. There are three types of horizontal joints, flush, keyed and weatherstruck. Flush joints are created by filling the joints, allowing it to harden slightly and then rubbing down until it is flush with the brick. Keyed joints can be achieved by pressing a piece of hose or similar tube along the joints whilst the mortar is still wet. Weatherstruck joints are sloped to allow rainwater to drain off. Vertical joints are sloped to one side and horizontal joints are sloped so the brick above overhangs the joint.
1. Mix up your mortar and start to push it firmly into the joints with a trowel. It is best to start with the upright joints and then the horizontal, and to work from top to bottom. Decide how you want to point the mortar (Flush, Keyed or Weatherstruck, see above) and complete each row or section of wall as you add the mortar.
2. Once the mortar has set, use an old broom to remove any remaining mortar dust and wash down any stains. Persistent stains can be hidden by rubbing them with an old brick. If the wall is particularly exposed, or the lack of proper pointing has allowed the bricks to be damaged, it is worth weatherproofing the whole wall once the new mortar has set.
Waterproofing the Wall
To finish the job it is a good idea to coat the bricks with a good water repellent. This will both prevent water from penetrating the bricks and improve insulation. Remember to only do this once any old and damaged bricks have been replaced and repointed. Following the manufacturers instructions, brush the water repellent solution liberally onto the wall, making sure that all of the bricks and joints are covered.