How do I know if it needs repointing or just looks tired?

Depth, not appearance. Push a key or a screwdriver into the joint. If it stops within a couple of millimetres the joint is sound and only weathered. If it sinks in, or the joint has receded behind the face of the brick so water sits on the brick edges, it needs raking out and pointing.

Why is the mortar softer than the bricks?

Because it is designed to be. Mortar is the sacrificial layer that takes the movement and the salt damage instead of the brick, and it can be replaced. Pointing a soft old wall in hard cement reverses that, and the brick faces then blow off instead.

Can I repoint in winter?

Not in frost. Fresh mortar that freezes before it cures is destroyed, which is one of the reasons a wall pointed a few winters ago can already be sandy. Bricklayers work to a temperature window and protect new pointing while it sets.

Only one patch of wall has gone — why there?

Something is keeping that patch wetter than the rest. A leaking gutter joint, a blocked downpipe, a splashing path, an overflow pipe or a failed cill are the usual answers. Point it without fixing that and the same square metre fails again.

Caution

Updated 30 August 2026

Crumbling Mortar Between Bricks

The mortar joints have gone sandy and you can rake them out with a key or a fingernail.

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What's happening?

Mortar is meant to be the sacrificial part of a wall. It is deliberately weaker than the brick so that movement and salt damage happen in the joint, which can be replaced, rather than in the brick face, which cannot. So mortar going soft after decades is the system working as intended. What is not normal is mortar that has gone sandy within a few years, or joints that have receded so far that water now sits on the exposed brick edges instead of running off the face of the wall. Depth is the test that matters. Surface weathering of a millimetre or two is cosmetic. Joints you can push a key into, on a wall that is getting wet inside, have stopped keeping weather out.

What usually causes it?

Ordinary weathering over decades, particularly on a south-westerly elevation that takes the driving rain
Mortar mixed with too much sand or too little binder when the wall was built or last pointed
Frost damage where saturated joints froze before the mortar had cured
Salt crystallisation in joints that stay wet, from ground salts or from de-icing salt near a path
Sulphate attack where joints are permanently damp, which softens and expands the mortar
Repointing done in the wrong weather, so the new mortar dried too fast or froze before it set
A leaking gutter, downpipe or overflow soaking one patch of wall repeatedly

Is it dangerous?

Not immediately, but it is progressive in a way that gets expensive. Once joints have receded past the brick arris, water sits on the horizontal edges rather than shedding, and the brick face itself starts to spall — at which point the repair is cutting out bricks rather than raking out joints. On a single-skin garden wall or a parapet, deep loss of mortar genuinely reduces stability because there is nothing else holding the courses together. Raking out is also dusty work: HSE names silicosis, COPD and lung cancer among the diseases caused by construction dust, and estimates that over 500 construction workers die from silica dust exposure every year, so dust extraction or water suppression is not optional on a grinder.

Can I fix it myself?

Small patches, yes, if you match the mortar. The rule that matters is that the new mortar must not be stronger than the brick or the original mortar — hard cement pointing on soft old brick pushes the damage into the brick face. Rake out to roughly twice the joint width, brush out the dust, damp the joint, and point in a mix appropriate to the wall, then protect it from sun, rain and frost while it cures. Do not point in freezing weather or full summer sun. Do not use an angle grinder to rake out unless you have on-tool extraction and respiratory protection, and never on a wall where the bricks sit tight to the joint.

When should you call a bricklayer?

Call a bricklayer where a whole elevation needs doing, where the wall is above ground-floor height, where the brick is soft or handmade and needs a lime-based mortar, or where damp is already showing inside. Also call if the mortar has failed again within a few years of being pointed, which usually means the mix or the weather was wrong rather than the wall.

What will the bricklayer actually do?

Test the existing mortar and brick hardness so the replacement mix is no stronger than what it is going into
Rake out failed joints to a sound depth by hand or with dust-controlled tools, without damaging the brick arrises
Match the mortar for strength, colour and sand so the repair does not read as a patch
Point and finish the joints to the wall's original profile, which is what governs how it sheds water
Protect the new work from rain, frost and direct sun while it cures
Trace and fix the water source — a leaking gutter, a failed cill, a bridged cavity — where one patch has failed alone

Frequently asked questions

We’re happy to answer all your questions.

Sources & References

Cement Pointing On An Old Brick HouseCaution Spalling Or Crumbling Brick FacesCaution Rain Coming Through A Solid Brick WallCaution Crumbling Mortar Along The Gable VergeCaution

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