Old brickwork often shows signs of damage to the pointing - that is where the cement has started to fall out from between the joints.
This is a normal part of the environmental damage that buildings have to face, a combination of rain and freezing temperatures.
Re-pointing a wall is important to preserve the integrity of the brickwork. There are two choices:
- If there is just a small amount of damage, you can simply patch re-point the damaged areas.
- If there is more extensive damage, you will need to remove all the old cement and re-point the whole area.
You can either hire someone to do this job for you (it won't be cheap), or do it yourself. Bear in mind that this is a time-consuming job that involves working at heights with power tools, so don't take it on unless you are sure you have the skill.
To do the job you will need:
- Scaffolding, an access tower, or a cherry picker - it is not safe to do this from a ladder
- A small Angle grinder (4.5 inch or 5 inch) with either a diamond tipped mortar raking blade or a mortar rake attachment and dust guide plate
- Pointing tools - these would include a couple of buckets, a pointing trowel, a brick jointer, a finger pointing trowel, a large soft brush, paint brushes, watering spray
- Pointing supplies - sand, cement and hydrated lime or Mastic, PVA bonding
- Safety equipment - safety shoes, ear defenders, industrial gloves, and a hardhat
Start at the top of the wall, this will stop dust from falling down onto your freshly re-pointed work. Clean out three courses of brick at a time, the full width of the area that you are doing.
Using your angle grinder and diamond tipped disk, remove the old cement from the horizontal joints to a depth of 10-20mm, then remove the cement from the vertical. Take care not to score the brick, this will ruin the look of the wall.
Then, use a large soft brush to remove all the dust from between the joints. Finally, wet the joints using either a watering spray on fine mist, or a wet paintbrush.
Carefully mix half a bucket or mortar - it is important that you are accurate, as you will need to repeat this mix, and it is essential that you do it the same each time in order to get a consistent colour! Alternatively, use mastic.
The typical mix is either a 6:1:1 mix of builders' sand/hydrated lime/cement, or a 3:1 mix of sharp sand/hydrated lime. Mix around half a bucket at a time -much more than that and it will start to go off before you use it.
Getting the consistency of the mortar right is important - if it is too wet it will be hard to apply and will slop all over the face of the bricks. It needs to be firm enough that you can cut it into narrow strips with the trowel and the strips stay in shape. The usual test is to see if it will stand up on the trowel without sagging.
Repeat the grinding, cleaning and re-pointing process until the whole area is finished.