Mortar falling out between bricks
If you're noticing pieces of mortar on your windowsill, path, or at the base of the wall, or if you can see the gaps between bricks getting wider, this is your wall telling you it needs attention. Mortar falling out is not just a cosmetic problem - it's a sign that the wall's weather resistance is actively failing.
Why mortar falls out
Age and weather exposure
Most brick and stone walls in Yorkshire were built with mortar that has a finite lifespan. Mortar joints on an exposed Victorian terrace may have been in place for 80 to 120 years. Even well-specified original mortar will eventually erode, and the process is substantially accelerated by the climate in this part of the country - wet autumns and winters, cold snaps, and wind-driven rain from the southwest.
Frost damage
Water entering a joint and then freezing puts enormous stress on the mortar. As the water expands, it physically breaks the material apart. Over successive winters this cycle can reduce a hairline crack to a fully open joint in just a few years. Properties in exposed locations around Skipton, Ilkley, and the Harrogate hills are particularly susceptible.
Incorrect mortar mix
A mortar that is too hard for the masonry it sits in will crack rather than flex with movement. This is a very common problem in older properties that have been repointed at some point in the past with a modern, high-cement mix. The mortar holds up initially, but as the softer brick or stone moves with temperature changes and moisture, the rigid joint cracks and eventually dislodges.
Poor quality previous repointing
If repointing was done without fully removing the old mortar first, or if joints were pointed to a shallow depth, the new material had insufficient bond and was always likely to fail prematurely.
How quickly does it progress?
Once mortar begins to fall out, the rate of deterioration increases. Open joints allow more water in. More water means more freeze-thaw stress. Wider joints allow more movement. A wall that loses a few pieces of mortar in a single winter can, within three or four years without repair, have widespread joint failure across an entire elevation.
The difference between surface erosion and complete joint loss
Surface erosion is when the mortar is recessed by a few millimetres but still solid at depth. The wall is losing its weather resistance at the face but is structurally intact. This is early-stage and the repair is less invasive.
Complete joint loss is when mortar has fallen out to significant depth - or entirely - leaving an open gap. At this stage water enters freely, bricks or stones are effectively unsupported at their edges, and there is a risk of bricks beginning to move. Frost spalling of the masonry face adjacent to open joints is common at this stage.
You can get a rough sense of which stage you're at by pressing gently on the joint with a finger or a key. If it gives way easily or crumbles, it's beyond surface erosion.
Structural implications if it's left too long
Mortar does more than keep water out - it distributes load evenly between masonry units. Widespread joint loss means bricks are effectively bearing on point contacts rather than being evenly bedded. Over time this can lead to movement, cracking, and - in extreme cases - structural instability.
Individual loose bricks are a clear warning sign. If you can see bricks that have shifted slightly from their original line, or if any appear to move when pressed, the repair is more urgent. We would always recommend an inspection before deciding on scope of work in this situation.
What repointing actually does
Repointing restores the joint by removing all the failed material back to sound depth, then filling the joint with new mortar matched to the building's age and construction type.
This:
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Restores the continuous weather-resistant skin across the wall
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Rebeds loose masonry units
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Prevents further frost damage within the joints
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Stops water tracking into the wall and appearing internally as damp
For buildings constructed before around 1920 - particularly stone properties - lime mortar is typically the correct material. Using hard cement on soft masonry causes more damage than it prevents. We always assess the existing mortar and masonry before specifying a mix.
See our cement mortar repointing and lime mortar repointing service pages for detail on each approach.
Other signs that indicate repointing is overdue
Beyond mortar visibly falling out, look for:
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Damp patches appearing on internal walls on the same face as failing joints
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Plant growth (moss, weeds, buddleja) in the joints - roots accelerate the damage
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Crumbling or loose mortar dust collecting at the base of the wall
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A visible shadow line running along joints, indicating they've eroded below the masonry face
If you are seeing damp inside as well as mortar loss outside, a Building Leak & Damp Inspection may be worth arranging to establish the full extent of water entry before repair work begins.
Frequently asked questions
Q1. How urgent is it if mortar is falling out between bricks? It is worth treating as a priority repair. Once mortar physically falls out, the joint is open and unprotected - rain enters directly, frost can force bricks apart, and the structural integrity of the wall begins to reduce. A wall can shed mortar gradually over years without obvious consequence, but once joints are open enough to see through or feel a gap with your finger, the deterioration tends to accelerate. Getting Northern Seal & Joint to inspect and advise early avoids what can become a significantly larger job. Q2. Does mortar falling out mean the wall needs rebuilding? Not necessarily. In most cases, repointing - raking out the loose material and replacing it with fresh mortar - is sufficient to restore the wall. Rebuilding is only required when the bricks themselves are displaced, cracked or badly spalled, or when structural movement has caused the wall to bow or lean. Northern Seal & Joint will assess whether the masonry is sound enough to repoint or whether any bricks need to be taken down and relaid before the joints are finished. Q3. What does repointing cost when mortar is actively falling out? The extent of the loss determines cost. Localised areas where a few joints have opened up are less expensive to address than a full elevation where the majority of beds and perpends are eroded. As a general guide, repointing in Yorkshire ranges from around £30–£60 per square metre for cement work, with lime mortar work typically higher. Northern Seal & Joint provides written quotes after inspection, covering the full scope so there are no surprises on the day. Q4. How long does repointing take once the work starts? A single, accessible elevation on an average semi-detached house can typically be repointed in one to two days. Larger or more complex jobs - multi-storey properties, scaffold requirements, extensive lime work, or heavily eroded joints requiring deeper raking - will take longer. Northern Seal & Joint gives a realistic timeframe at the quoting stage. Work is generally carried out in a single visit where possible, minimising disruption. Q5. Does the weather affect when repointing can be carried out? Yes. Fresh mortar needs reasonable conditions to cure properly: ideally above 5°C and not raining. Applying mortar in frost risks the mix failing before it sets; rain on freshly pointed joints can wash out the surface. In Yorkshire's climate, this means some flexibility in scheduling is required, particularly for lime mortar which is more sensitive than cement. Northern Seal & Joint monitors conditions and schedules work accordingly, so the repair lasts as it should. Q6. What causes mortar to fall out in the first place? The most common causes are natural weathering over time (mortar has a finite lifespan), use of an incorrect mix that was too hard or too soft for the brick type, poor original workmanship, and freeze-thaw cycling in exposed positions. Yorkshire's wet winters accelerate deterioration in joints that have already weakened. In older properties, original lime mortar may simply have reached the end of its life and needs renewing - this is entirely normal maintenance on a building of age.
Recent local work -
