Whilst it might not be one of the most glamorous jobs when it comes to your house renovation, repointing brickwork is a hugely important aspect of a building project.
The mortar you use when repointing brickwork could account for as much as 15 per cent of the overall surface area of the exterior of your home, be it of brick or stone construction — meaning it has a massive impact not only on the stability and performance of your home, but also on its final appearance.
Get the repointing wrong at your peril. Poorly mixed mortar, inappropriate materials, the wrong colour or that which is badly matched to existing mortar, not to mention mortar that has been badly applied – spread all over the brick face itself, for example – will spoil even the best brickwork. This is huge shame as, done well, repointing brickwork can give an alluring texture and shadow to any elevation.
Repointing brickwork provides a primary defence against water ingress, as well as having a vital structural role — it is also a critical aspect of a home’s maintenance schedule and shouldn’t be ignored. When taking on a renovation project, repointing brickwork should be high on the priority list — it can often be a source of leaks and damp in homes in need of wider renovation.
Although some renovators do choose to take on the job of repointing brickwork on a DIY basis, given the requirement for working at heights it is usually a job that is outsourced to a professional.
Repointing Brickwork Essentials
What is Mortar?
Mortar is the substance that separates individual masonry units (such as brick or stone) from one another. It protects the building from the effects of weathering and water ingress and is also used to fill any irregularities on the bedding faces of the bricks or blocks (the bedding is the mortar used to bind the bricks to one another.)
Whether your home is built of brick, stone or concrete blocks, mortar will play an important part in your home’s construction.
Mortar can be made up of a variety of different materials (see Which Mortar, below). It is softer than bricks and stone, explaining why at some point in the life of a building, it will begin to show signs of ageing. Although it might be a pain, this is the way things are supposed to happen — the alternative is that the mortar is harder than the bricks and that they take the brunt of weathering, eroding and resulting in areas of wall deteriorating — an expensive and disruptive job.
Repointing brickwork is simply the task of renewing the outer portion of the mortar joint, and a good repointing job on your home should last up to 50 or 60 years.
When Should I Repoint Brickwork?
If you can easily see open joints around the mortar bed, then it is time to think about repointing. This is a straightforward job and the materials required to carry it out are not expensive.
On the downside, the cost of the labour involved in brickwork repointing can be quite considerable as it is a fairly labour-intensive task. It can also be hard to find a builder willing to come out for just small areas of repointing, which is why many people choose to carry out repointing on a DIY basis. DIY brickwork repointing can requires scaffolding hire.
Which Mortar is Best?
A large range of textures and colours (from dark to light) can be achieved when mixing mortar. The majority of homes built up to and including the Victorian era used lime mortar.
The use of cement in repointing mixes does tend to be a bad thing (although it is still frequently done) causing decay to occur earlier than with lime mixes and damp more likely to raise its head. Cement mortars are harder, more brittle and less porous than lime and will weather slower than the bricks themselves.
Mortars containing cement tend to be more susceptible to salt and sulphate attack, while mortars containing only lime (putty or hydraulic) and sand are not vulnerable to this kind of damage. Lime mortars are more expensive than cement — but in the long run they can actually save money as putting right problems caused by inappropriate cement mixes can be costly.
Repointing a Wall: A Step-by-Step Guide
Tools and Materials Needed:
- Cement mixer
- Pointing trowel
- Mortar board
- Soft brush
- Wire brush
- White cement
1. Repointing brickwork is clearly high priority on this wall. Not only is there a mixture of materials, but the profile of the pointing ranges from semi-recessed to plastered-on-top — not good. As with many renovation projects, plants have been growing up against the walls — these should be pinned back and then tethered into place before any work can start on the building. Repointing brickwork is a messy job so plastic sheets should be laid over flower beds, new paving and areas of grass.
2. The old pointing is removed with a hammer and chisel, with particular care taken near the areas shown in the following four steps. Disturbing old mortar around windows can affect the way they fit (and open). The chisel is used on its own to chip out only the loose material.
3. Take care around doorways — if mortar gets pushed into the gap between the wall and the frame it can cause the door frame to move and make the door hard to open and close. Loose mortar is raked out gently with a narrow chisel. Metal gutter brackets are prone to falling out if they are disturbed during the chopping-out phase. Power cables for external lighting is often run inside the pointing so take care. It was easy to spot on this job because the joint was a different colour in the course leading up to the lamp.
4. This is what is left after the old mortar has been removed. The edge of the stone is revealed all round and there is now a gap wide enough to take (and hold) the fresh mortar which will soon be applied to the wall.
5. Plenty of dust is left in the gaps between stones afterwards. This is brushed out before repointing begins.
6. To keep the colour of the mortar consistent for the whole job, the mix is carefully measured out. In this case, three buckets of yellow building sand, one bucket of lime and a quarter bucket of white cement. Each full bucket is levelled off at the top while the quarter-full bucket of white cement is measured off to a line drawn inside the bucket.
7. Repointing is generally done from the top of the wall downwards. However, the first half metre of a solid wall without a damp-proof course (as here) holds a lot of moisture so this section is done first — giving it more time to dry. The mortar is pushed in firmly, working from right to left.
8. Once two or three courses have been repointed, the vertical joins between are filled too. Notice that the mortar is allowed to overlap all the joints and no attempt is made at this point to neaten it up. With the bottom half metre of the wall complete, the top section is started. Within five hours, a team of two complete this stage on this 24m2 wall. The mortar is left until nearly dry. How long the drying process takes depends on the weather and the position of the house in relation to the sun. In this case, the mortar is ready in just a couple of hours.
9. A wire brush is used to take off the excess mortar and leave a face joint that is only just recessed from the face of the wall. In other areas of the country, a deeper joint or one that is flush with the wall may be more appropriate. The wire brush also cleans up the stonework as it moves over the surface.
10. A close-up of the finished job. With the face joints now clearly defining the stones, the wall not only looks great, it is ready to withstand years of weathering.
Repointing Brickwork: Top Tips
- Using a narrow chisel around windows and doors minimises the risk of pushing loose pieces further in around the frames
- The use of an angle grinder should really be avoided — it is easy to slip and damage the face of the brickwork or stone and is unnecessary with most traditional lime-based mortars
- When you have a space large enough to take the new mortar, stop raking out and brush the joints down. Then give the joints a spray with water — this helps the new mortar dry out evenly. Wait for the water to dry off before repointing
- Aim to replicate the colour, texture and durability of the existing mortar. Carefully measure each component of your mortar and make a note of the quantities used to ensure each bucket load matches the last
- Begin from the top down (in order to keep any dust and water spray away from freshly repointed joints)
- A slightly open final texture tends to look more attractive than a very smooth one. An easy way to achieve this is to gently rub the filled joint with a stick or rubber, and then to softly brush it over before it dries
- To avoid the new mortar drying out too quickly, spray the joints lightly with water from time to time