9 Feb 2026
Crumbling Mortar? When Repointing Is Urgent
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Mortar is meant to be the sacrificial part of a brick wall. It takes the weathering so the bricks do not have to. When mortar starts failing, the goal is not “make it look new”. The goal is keep water out, keep the wall able to dry and stop bricks taking the damage.
If you want the work done professionally and matched to your property, this is the most relevant service page: Brickwork Services for Homes.
Do I need repointing right now?
Repointing is usually urgent if:
Mortar is missing deep enough that you can push a key into the joint
Bricks are starting to flake or crumble (spalling), especially after frosty weather
You have damp patches that get worse after rain on the same wall area
The wall is exposed (chimneys, gable ends, parapets) and joints are open
It can usually wait (but still needs booking) if:
Mortar is powdery on the surface but still mostly intact
Cracks are hairline and not opening up
The issue is limited to one small patch that is sheltered from weather
Tip that saves money and prevents overwork: Historic England advises that comprehensive repointing is rarely necessary, and often it is only the most exposed or problem areas that need attention.
What is repointing brickwork?
Repointing is the process of removing failed mortar from joints and replacing it with new mortar that:
matches the building (strength, permeability, appearance)
protects the edges of the bricks
allows the wall to handle rain and then dry out normally
On older buildings, the mortar is often lime-based, and that “breathability” matters. SPAB explains that lime (or occasionally clay) mortars are typically most appropriate on old buildings, and the new mortar should be selected to match the existing in strength, texture and colour.
What are the signs you need repointing?
1) Mortar is missing or falling out
If joints are open, wind-driven rain can get into the wall and freeze-thaw damage speeds up.
2) Mortar is cracking in long runs
Cracks that follow joint lines often mean the mortar is too rigid for the building’s movement, weathering, or moisture patterns.
3) Bricks look like they’re “breaking down”
If brick faces are flaking, crumbling, or popping off, that is a red flag. SPAB warns that when lime mortar is replaced with impervious cement, the bricks can become the sacrificial element instead, leading to erosion of the brick or stone.
4) Damp patches appear after rain
This is where repointing becomes more than cosmetic. Open joints, failed pointing at parapets, and chimney junctions are common culprits.
If the damp is mixed with condensation or mould inside, pair this article with your ventilation guide: Awaab’s Law and Damp/Mould: The 2026 Ventilation Checklist.
When is repointing urgent?
Use this simple urgency check.
Repointing is urgent if you see any of these:
Open joints on a chimney stack or high gable wall
Loose mortar dropping onto paths, patios, or lower roofs
Visible gaps around window/door reveals that let water track in
Rapid deterioration after frost
Bricks spalling or crumbling at the edges
Repointing is “book it soon” if:
Joints are weathered back unevenly but still mostly filled
You have small isolated patches in sheltered areas
The wall looks tired but you have no damp symptoms yet
If you ever suspect an immediate safety issue (loose masonry, sudden water ingress, damage after storms), use the decision tree here: Is This an Emergency Repair?.
Why the wrong mortar mix causes damage
This is the big one, and it’s where a lot of “quick fixes” go wrong.
Cement mortar on an older wall can trap moisture
Many older buildings were built with softer, more permeable mortars. If you repoint with a hard, dense cement mortar, moisture can be forced to escape through the bricks instead of the joints.
SPAB is very direct about this: inappropriate cement pointing can cause erosion of bricks and stones because they become the most permeable part of the wall and suffer frost and salt action.
Historic England also emphasises the role of lime mortar joints in helping buildings dry, and that they are designed to be a sacrificial layer requiring maintenance over time.
The goal is compatibility, not maximum hardness
The “best” mortar is the one that suits your wall. Strength, flexibility, and permeability should align with the brick and the age of the building.
If your home is older, listed, or in a conservation area, it’s even more important to get the mortar choice right. Local authority guidance often stresses preserving sound historic pointing and avoiding replacement purely for aesthetics.
What does good repointing look like?
This is what best practice tends to include.
1) Proper raking out depth (not a skim)
A common failure is smearing new mortar over old joints. It looks fine for a few months, then falls out.
LABC notes that to repoint correctly, old mortar should be raked out to a suitable depth and not simply skimmed over the top, because thin layers won’t adhere or withstand weathering.
2) Matching mortar to the building
Colour matters, but performance matters more: permeability, strength, and aggregate choice.
SPAB advises matching existing mortar in colour, texture and strength, and that suitability can often be assessed by inspection and local knowledge.
3) Doing the right areas, not necessarily everything
Historic England’s guidance points out that comprehensive repointing is rarely needed, and sound historic mortar should be left undisturbed.
4) Respecting weather and curing
Repointing is sensitive to cold snaps, heat, wind, and rain. Getting the timing and curing right is part of durability.
A homeowner’s checklist before you book repointing
Walk the property and note:
Which elevations are worst (front, rear, gable)
Whether damage is concentrated at chimneys, parapets, or below gutters
Whether the worst patches correlate with rain direction
Whether bricks are starting to spall
Take a few photos. It speeds up diagnosis and helps you avoid “repoint everything” quotes when only certain areas need attention.
FAQs
Can I repoint one patch or does it all need doing?
Often, you can do the exposed and failing sections only. Historic England’s guidance supports targeted repair, with sound mortar left alone.
How do I know if my house needs lime mortar?
If your property is older (often pre-1919 as a rough guide), lime mortar is common, but the right answer depends on what’s already there and how the wall behaves. SPAB explains lime mortars are usually appropriate for old buildings and stresses matching strength and characteristics.
Is it okay to repoint in winter?
It depends on conditions. Mortar performance is affected by temperature and curing. It’s one reason professional scheduling matters.
Is repointing just cosmetic?
No. It’s part of weatherproofing and protecting masonry. Done well, it helps prevent water ingress and stops bricks taking unnecessary damage.
When you want it assessed properly
If your mortar is failing, the safest move is to get a proper look and a compatible repair plan, especially on older brickwork.