How to repoint brickwork

Inspired by a DIY Doctor UK guide. This walk-through is based on "Pointing and repointing brickwork and blockwork" published by DIY Doctor, the UK’s established DIY advice website. It covers the preparation and application stages clearly, including the difference between bucket-handle and flush joint finishes. Worth watching before you mix anything up.

1. Assess how much repointing is needed

Run a screwdriver along the mortar joints. If it sinks in easily or crumbles away, those joints need repointing. Soft, recessed, or visibly cracked mortar is also a clear sign. Hollow-sounding mortar (tap it with a coin) has failed beneath the surface.

A few isolated joints here and there is a manageable afternoon job. If more than a third of a wall looks poor, get a professional opinion first — the wall may have a structural or damp issue that repointing alone will not solve.

2. Rake out the old mortar

Use a cold chisel and club hammer to rake out the old mortar to a depth of at least 20 mm. Shallower than that and the new mortar will not get a proper key and will pop out again fairly quickly. Work carefully so you do not chip or crack the brick faces.

An angle grinder with a mortar-raking disc makes this faster on larger areas, but it requires care and appropriate safety equipment — dust mask, eye protection, and ear defenders at minimum.

3. Clean out the joints thoroughly

Blow out the loose dust and debris from the joints with a stiff brush or an air line if you have one. Then dampen the joints with a brush and clean water. This stops the dry brick from drawing moisture out of the new mortar too quickly, which would weaken it.

Do not soak the brickwork. Damp is the aim, not wet. Excess water sitting in the joint will dilute the mix and give a weaker result.

4. Mix the right mortar

For most UK brickwork, a mix of 1 part cement to 5 or 6 parts soft sand is about right. For softer older bricks — Victorian or Edwardian properties, for instance — a weaker, more flexible mix using lime is usually better. Hard cement mortar on soft old brick traps moisture and can damage the bricks themselves.

Mix small batches. Mortar starts to go off after an hour or so and you cannot retemper it once it begins to stiffen.

5. Apply the new mortar

Load mortar onto a small pointing trowel or a hawk and use a narrow pointing trowel (or a brick jointer) to press it firmly into the joint. Do the vertical joints first, then the horizontal beds. Push the mortar in hard to make sure there are no air pockets.

Build up slightly proud of the brick face to allow for finishing. Do not try to do too large an area in one session — a square metre at a time is a sensible pace for most people.

6. Finish the joints and let them cure

Once the mortar has firmed up but is not yet hard — usually after 20 to 30 minutes depending on conditions — finish the joints. A bucket-handle profile (slightly recessed, rounded) is the most common and sheds water well. A flush finish suits some older or rougher brickwork.

Keep the finished joints damp for the first day or two by misting with water, especially in hot or windy weather. New mortar that dries out too fast will be weak and prone to cracking.

When to call a handyman

Repointing a low wall or a ground-floor section yourself is reasonable. Call Richard if the wall is high, you are on scaffolding or a ladder for extended periods, the brick faces are damaged, or the problem looks more serious than surface mortar failure. Damp getting in through failed pointing can cause significant damage inside — it is worth getting right.