How to Repoint a Brick Wall – DIY Guide
Driveways & External › Brickwork
How to Repoint a Brick Wall
Restore crumbling mortar joints and protect your brickwork from water damage.
To repoint a brick wall, rake out the old mortar to a depth of 15–20mm, brush away dust, dampen the joints, and pack in fresh mortar mix. Work from the top down, finishing each joint neatly before the mortar sets. A standard garden wall takes a full day.
- Angle grinder with mortar-raking disc
- Cold chisel
- Club hammer
- Stiff-bristle brush
- Pointing trowel
- Bucket and mixing paddle
- Soft brush
- Safety goggles and dust mask
- Ready-mix repointing mortar or sand and cement
- Plasticiser additive
- Clean water
- Mortar colourant (optional)
- Dust sheets
- Masking tape (for decorative brickwork)
Step-by-Step Guide
Assess the Wall and Plan Your Work
Before you start, inspect every joint across the wall. Press your finger into the mortar — if it crumbles or is recessed more than 5mm, it needs repointing. Mark off any areas where the mortar is still sound so you only remove what is necessary. Check the brick faces too: spalling or cracked bricks should be replaced before you repoint, not after. If the wall is a boundary wall or retaining wall, see our Driveways & External Guide for structural checks before starting any remedial work.
Rake Out the Old Mortar
Use an angle grinder fitted with a mortar-raking disc to remove the old mortar to a depth of 15–20mm. For tight or decorative joints where a grinder is too aggressive, use a cold chisel and club hammer, working carefully to avoid chipping the brick faces. Always wear safety goggles and an FFP2 or FFP3 dust mask — mortar dust contains silica, which is a serious respiratory hazard. The Health and Safety Executive classifies respirable crystalline silica as a carcinogen, so dust control is not optional.
Clean Out the Joints
Once the old mortar is raked out, brush all joints thoroughly with a stiff-bristle brush to remove every trace of loose dust and debris. Vacuum out the joints if you have a suitable attachment. Any remaining dust or powder will prevent the new mortar from bonding properly. Dampen the joints with clean water using a brush or a misting spray — saturated joints are too wet, but bone-dry masonry will pull moisture from the mortar too quickly, weakening it.
Mix the Mortar to the Right Consistency
For most external brick walls, use a 1:4 mix of cement to sharp sand, plus a small measure of plasticiser to improve workability. If you are matching existing lime mortar on an older or listed building, use a lime-based mix rather than cement — cement mortar is too rigid for traditional masonry and will cause brick damage over time. Mix to a firm but pliable consistency that holds its shape without slumping. Only mix what you can use within 30 minutes. If your wall runs alongside a patio, check our guide on how to repoint patio slabs — the mix ratios differ.
Apply the Fresh Mortar
Working from the top of the wall downwards, load mortar onto a hawk and press it firmly into the joints using a pointing trowel. Pack the mortar in two layers for deep joints, allowing each layer to stiffen slightly before adding the next. Match the joint profile of the existing brickwork — a slightly recessed weatherstruck joint sheds water well on exposed walls. Flush joints are common on older walls but collect water more readily. A bucket-handle or half-round profile is another good choice for external walls. Avoid working in frost, rain, or direct summer sun, as all three will compromise the mortar cure.
Finish and Cure the Joints
Once the mortar has begun to firm up but before it fully sets — usually 30–60 minutes depending on temperature — run a jointing tool or the edge of a trowel along each joint to achieve a clean, consistent finish. Brush the wall face gently with a soft brush to remove any mortar smears before they harden. Keep the freshly pointed joints damp for two to three days in dry weather by misting lightly with water — this slows the cure and produces stronger mortar. Do not allow the wall to freeze during the curing period.
Frequently Asked Questions
What is the best mortar mix for repointing an external brick wall?
For most modern external brickwork, a 1:4 cement-to-sharp-sand mix with plasticiser is correct. For walls built before 1919 or with soft handmade bricks, use a lime-based mix — typically 1:2.5 NHL 3.5 hydraulic lime to sharp sand — to avoid locking in moisture and damaging the bricks.
How deep should I rake out the old mortar?
A minimum of 15mm and ideally 20mm. Anything shallower does not give the new mortar enough depth to bond and develop strength. If the original mortar is very soft, rake back until you reach sound material, even if that means going deeper than 20mm.
Can I repoint a wall in winter?
Only if air and surface temperatures are reliably above 5°C, both during application and for at least 48 hours afterwards. Frost will destroy uncured mortar. If frost is forecast, cover the freshly pointed wall with hessian or polythene sheeting overnight.
How do I know if my wall needs repointing or full rebuilding?
If the mortar is crumbling or recessed but the bricks are intact and the wall is plumb and stable, repointing is the right repair. If bricks are spalling, the wall is leaning, or large sections of mortar are missing, get a structural assessment before starting any remedial work. Our Driveways & External Guide covers when to call a professional.
Do I need to seal the wall after repointing?
Generally no — well-pointed mortar joints are the primary weatherproofing. Masonry sealants can trap moisture behind the surface and are usually only necessary on very exposed or porous bricks. If the brickwork itself is absorbing water heavily, investigate the cause before applying any sealer. You may also want to check our guide on repairing cracked driveways if you have broader external maintenance to tackle at the same time.
Dampen the joints in two passes, ten minutes apart, rather than one heavy soak — this ensures moisture penetrates the brick face without pooling at the bottom of the joint, which would dilute the mortar as you apply it. A consistent substrate moisture level is the single biggest factor in how well new pointing bonds and how long it lasts.
Sources
- HSE — Silica and construction dust: health risks and controls — hse.gov.uk
- Historic England — Mortars, Renders and Plasters (Practical Building Conservation) — historicengland.org.uk
- Which? — Repointing brickwork: how to repair pointing — which.co.uk
This guide is for general information only. Always work safely and follow manufacturer instructions. DIYnut accepts no liability for injury or damage arising from DIY work.
