Mortar is a common material used in construction. Despite what you might think, the idea of mortar isn’t to hold bricks or stones in place; what it actually does is help to shape a structure, while also ensuring that its weight is evenly distributed. The substance is also one of your property’s main defences against moisture related issues such as damp, leaks and moss growth.
Over time, typically after a few decades, mortar will wear down or begin to fall away as a result of weathering. As this gets worse, your property will become more and more vulnerable. To avoid this, it is necessary to repoint walls as the mortar inside begins to wear away.
Although pointing or repointing a wall is not a complicated job, it is highly labour intensive. Because of this, it can be wise to speak to a local builder or bricklayer if the space you need to work on is large. Having said this, many tradesmen will not accept jobs for small repointing small areas because they are not worth enough money. For work like this, it can be best to make the project into a DIY job or to hire an experienced handyman. Depending on the height of your pointing or repointing work, you may also need to hire a scaffolder so that the job can be done safely.
Whatever you do, don’t just choose the first mortar kit you find on the shelf. Taking the time to consider the kind of mortar that you are using will save you a lot of grief down the line.
The first thing to think about is the composition of your mortar. Usually the best mixtures are made up of sand, cement and lime, but the use of mortar that contains little lime is quite widespread. This is mainly because of price rather than any advantages: sand/ cement mortar is harder, more brittle and less porous than lime mortar. Because it is usually more hardwearing and resistant to moisture than brick, it can actually make a wall structurally vulnerable. If movement occurs, non-flexible sand/ cement mortar could cause the bricks to crack. The lack of permeability can also lead to issues like efflorescence, fungal growth and damp. While lime mortar is more expensive, it has more elasticity, flexibility and permeability, which will be a real benefit for your wall.
Another important thing to think about is colour. For the sake of maintaining the look of your wall, you will want to match the colour of the original mortar. Getting this right can be difficult, as the ingredients themselves can come in a number of different colours. You may have to go through a process of trial and error to get the colour you want; once you have the mixture, note the ratio down and stick to it firmly. If you are able to contact the builder who originally pointed the wall, you can save yourself a great deal of time by getting the ingredients from them.
Do not try to save time by mixing a lot of mortar together at once: the mixture will dry very quickly, making it unusable.
You will want to focus on around one square meter at a time as you work; again, mortar dries very quickly, so it helps to not try and use too much at once. Before you get started, tie back any plants that are growing up your wall, as they will get in the way otherwise. If you have any flowers or accessories at the bottom of your wall, cover them up with a dust sheet before you begin.
The first step will be to remove any loose or damaged mortar from the wall. You can do this with a hammer and a thin chisel, but do not be fooled: you want to go slowly and carefully! For any pieces of mortar which are already loose and hanging out, remove them with just your chisel.
Be particularly careful when removing the mortar around windows or doors. If you make a mistake here, you could affect how well they open and close.
You will need to remove around 10mm minimum from your brickwork before you start repointing. It is important to note at this point that you should not use a disc cutter or ankle grinder for this kind of job. You might think that these tools would make the work go faster, but they can be very difficult to control. If you fail to hold them steady, you may end up damaging your brickwork.
This process will leave a lot of dust behind, so use your soft brush to get rid of this before you start repointing. Where you should start repointing will depend on whether or not your wall has a damp proof course. If it does not, the lower sections could be holding a great deal of water, which will make the mortar take longer to dry. With these walls, you can start with the courses up to around two feet from the bottom of the wall. If the wall does have a damp proof course, you will start from the top and work your way down.
Holding up your mortar board, flatten out the mortar until it is around the height of the lateral courses between the bricks. Taking a strip of mortar on the edge of your trowel, scrape it off into the joint by pulling the trowel upwards. Keep using this technique to build up the mortar, letting it overlap the joints (don’t worry, we’ll clean this up later.) You will want to push the mortar into three bed (horizontal) courses before filling the head (vertical) joints between them.
Once the work is finished, leave the wall for a few hours, until the mortar is nearly dry. After this, start using your wire brush to remove excess mortar from the surface of the wall. As well as improving the appearance of the mortar, this should also give the surface of your wall a nice clean look.