The short answer
The clearest signs you need repointing are mortar joints that are crumbling, cracked, recessed or missing, often loose enough to rake out by hand. Other warnings include spalling brick faces (the outer surface flaking away to expose a lighter, rougher core), white powdery efflorescence on the brick as moisture moves through and evaporates, gaps where daylight or draughts come through, plants or moss taking root in the joints, and unexplained internal damp on an external wall — especially on the elevation facing the prevailing weather. On a pre-1920 home, damp that is not down to a leaking gutter or roof is often caused by failed or inappropriate pointing. Any of these means water can get into the wall, so it is worth acting before the brick itself is damaged.
Failing pointing usually shows on the outside before damp shows on the inside. Knowing what to look for lets you repoint while it is still a mortar job rather than a brick-replacement one. Here are the signs that matter.
What to look for
- Jointscrumbling, cracked or recessed
- Loose mortarrakes out by hand
- Brickspalling / flaking faces
- Surfacewhite efflorescence
- Insideunexplained damp
Signs on the wall
- Crumbling or receding joints: mortar that is soft, cracked, sunken or missing — if you can rake it out with a key or screwdriver, it has failed.
- Spalling brick: the outer face of bricks flaking or breaking away in layers, exposing a lighter, rougher core — a sign moisture is freezing and expanding behind the surface.
- Efflorescence: a white, powdery salt deposit on the brick, left where water has moved through the wall and evaporated.
- Gaps and growth: daylight, draughts, moss or small plants in the joints — all signs the mortar no longer seals the wall.
Signs inside, and why timing matters
Failed pointing lets water into the wall, so it can show up indoors as damp patches, mould or staining on external walls — typically on the elevation that faces the prevailing wind and rain. On a property built before 1920, damp on an external wall that is not explained by a leaking gutter or roof is one of the most common signs that the pointing has failed or that an inappropriate cement mortar is trapping moisture. Repointing while the problem is in the joints keeps it a mortar job; left too long, water reaches and damages the bricks themselves, turning it into the costlier brick-replacement work.
| Sign | What it usually means |
|---|---|
| Crumbling / missing joints | mortar has failed — repoint |
| Spalling brick faces | moisture freezing behind the surface |
| White efflorescence | water moving through the wall |
| Internal damp on outer wall | water getting past the pointing |
General guidance — a specialist should confirm the cause on your wall. Source: SPAB and trade repointing guidance.
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Frequently asked questions
How do I know if my wall needs repointing?
Look for crumbling, cracked, recessed or missing mortar joints — especially if you can rake the mortar out by hand. Spalling brick faces, white efflorescence, gaps with moss or plants, and unexplained internal damp on an external wall are all signs the pointing has failed.
What is spalling brick and is it serious?
Spalling is where the outer face of a brick flakes or breaks away, exposing a lighter, rougher core, usually because trapped moisture freezes and expands. It often goes with failed pointing and means water is getting into the wall — worth acting on before more bricks are damaged.
Can failed pointing cause internal damp?
Yes. When joints crumble or an inappropriate hard mortar traps moisture, water can reach the inside face of the wall, showing as damp, mould or staining — most often on the elevation facing the prevailing weather. On pre-1920 homes this is a common cause of otherwise unexplained damp.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific wall. They are guidance, not a quotation.