Cracked or missing mortar letting water into your walls
Mortar joints do a job that's easy to overlook. They bind the masonry together, yes, but they also form a continuous weather-resistant skin across the wall. When they fail, rainwater doesn't just sit on the surface - it travels through, into the structure. Over time, that leads to damp, frost damage, loose bricks, and escalating repair costs.
This is one of the most common problems we fix across Yorkshire. It's also one of the most commonly underestimated.
Types of mortar failure
Not all mortar failure is the same, and understanding the type helps determine how urgently repair is needed.
Surface erosion
The joint face is recessed, sandy or soft to the touch, but the mortar goes some depth into the joint before it's solid. This is early-stage failure. The joint profile is losing its weather resistance - water is sitting in the recess rather than shedding off - but the structural integrity of the wall is not yet compromised. Repair is straightforward but shouldn't be left too long.
Through-cracking
A crack runs along or across the joint, sometimes following the mortar line, sometimes running diagonally through it. This allows water to travel directly through the joint under pressure. Cracking is often caused by building movement, differential settlement, or thermal cycling. It can also indicate that the mortar mix was too hard for the masonry (a common problem with modern cement-heavy mixes applied to older soft brick).
Complete joint loss
The mortar has eroded or fallen out entirely, leaving open gaps between bricks or stones. At this stage, water enters freely, and in cold conditions the water that enters will freeze, expanding within the joint and spalling the faces of the masonry. Structural integrity can also be affected if joint loss is widespread.
How to assess severity yourself
Stand at arm's length from the wall and look along the joints. If joints appear flat and solid, with no visible recess or cracking, they're likely in reasonable condition. If you can see a shadow along the joints - mortar sitting below the face of the brickwork - that's a sign of erosion. If you can see gaps, or if you can press a key or probe into a joint easily, repair is needed.
Pay particular attention to the most exposed elevation - usually the south or west face of the building. These fail first. In Yorkshire, southwest facing elevations take the most punishment from driving rain, particularly on properties above 200 metres. Areas around Harrogate, Ilkley, and the Skipton fringe are notably exposed.
The freeze-thaw cycle and why it matters in Yorkshire
Yorkshire winters are reliably wet and regularly produce frost. This combination is particularly damaging to masonry.
When water enters a cracked or open joint and the temperature drops, that water expands by roughly 9% as it freezes. In a tight joint, that expansion puts enormous stress on the surrounding masonry. Over successive freeze-thaw cycles - which can occur dozens of times in a single winter - the masonry faces begin to spall (flake off) and joints widen further. What began as a surface crack can, within a few winters, become a significant structural defect.
Repairing joints before winter arrives is always preferable to repairing them after.
Cement mortar vs lime mortar failure
The type of mortar that has failed matters, because the repair material needs to match.
Cement mortar failure (more common in properties built after about 1920) typically presents as through-cracking or surface hardness loss. Cement mortars have a finite lifespan and will eventually degrade, particularly if the original mix was too strong for the masonry.
Lime mortar failure (more common in older stone and brick buildings, typically pre-1920) usually presents as erosion or washout rather than cracking. Lime mortar is deliberately softer than the masonry, allowing the wall to breathe and allowing any movement to be accommodated in the joint rather than the brick or stone. Replacing lime mortar with a hard cement mix is a common and serious mistake - it transfers stress to the masonry face, causing spalling and long-term damage.
If you have an older property, particularly stone-built or soft-brick construction, it's important that the correct mortar type is used. We assess the building before recommending a mix. See our lime mortar repointing service for more detail.
When repointing is needed vs when it isn't
Repointing is not always the answer. If mortar joints are in reasonable condition but brickwork is still taking in water, the issue may be porosity of the masonry itself rather than the joints - in which case a breathable water-repellent treatment may be the right approach. If cracking is severe and follows a structural pattern (diagonal staircase cracking, cracks over 5mm wide), a structural assessment should come before repair work.
Repointing is the correct response when joints are visibly eroded, cracked, or missing - particularly where this has allowed water to reach the internal face of the wall.
What to expect during a repointing job
-
Failed mortar is raked out to a consistent depth (typically 25–30mm) using mechanical or hand tools appropriate to the masonry type.
-
The exposed joint faces are cleaned of dust and debris and dampened to prevent the new mortar drying too rapidly.
-
New mortar is mixed to match the strength and profile appropriate to the building. On a lime-pointed property, this means a lime-sand mix; on a modern property, a cement-based mix.
-
Joints are filled and struck to match the existing style - flush, weathered, or recessed as appropriate.
-
The finished surface is allowed to cure. Lime mortars require longer curing and protection from rapid drying.
The work is usually completed elevation by elevation. Most domestic repointing jobs are complete within one to three days depending on the area involved.
See our cement mortar repointing and lime mortar repointing service pages for more detail. If you're also seeing cracked or damaged masonry alongside failing joints, our masonry repair service addresses these alongside repointing.
Frequently asked questions
Q1. Is repointing always necessary, or can cracked mortar be left? No - cracked mortar does not always require immediate repointing, but it does need monitoring. Hairline cracks in a sound mortar may not allow significant water ingress. However, open joints, eroded beds deeper than 10–15 mm, or any area where water is visibly tracking inside should be addressed promptly. Left untreated through a Yorkshire winter, freeze-thaw cycles will widen cracks and dislodge further material, turning a straightforward repoint into a larger repair job. Q2. Do older properties need lime mortar rather than cement? Yes, in most cases. Properties built before around 1920 were typically constructed with lime mortar, and the bricks or stone used are softer than modern materials. Applying cement mortar to these walls causes moisture to be driven into the masonry rather than escaping through the joints, which leads to spalling, cracking and accelerated decay. Northern Seal & Joint always assesses the building's age and construction type before recommending a mortar mix, to ensure compatibility with the existing materials. Q3. What does repointing typically cost per square metre in Yorkshire? Cement repointing typically costs in the region of £30–£60 per square metre, depending on joint condition, access requirements and how much defective mortar needs to be raked out. Lime repointing costs more - often £50–£90 per square metre - due to the specialist materials and slower working pace required. These are guide figures only; Northern Seal & Joint provides detailed written quotes after inspecting the property, so you know exactly what is covered before work begins. Q4. How long does repointing last once it has been done properly? Good-quality cement repointing on a modern property should last 20–30 years in normal conditions. Lime repointing, when mixed and applied correctly, is similarly durable and in many cases outlasts cement on older buildings. The main factors affecting lifespan are mortar mix, joint preparation, weather during curing, and whether the correct material was chosen for the substrate. Work carried out with proper preparation on exposed Yorkshire elevations will outlast a quick patch job by many years. Q5. Can I repoint brickwork myself as a DIY job? For small, accessible areas on a modern property, competent DIYers can repoint with reasonable results using the right tools and mortar. However, the most common DIY mistake is using too-strong a cement mix, which can cause the bricks to crack and spall. Getting the joint profile right also takes practice - a poorly finished joint collects water rather than shedding it. For anything above ground level, larger areas, or older properties requiring lime mortar, professional work is strongly advisable. Q6. What are the signs that mortar joints need repointing? The clearest signs are visible cracking or open gaps in the joints, mortar that crumbles or comes away when you press it, recessed joints where mortar has eroded back 10 mm or more, water staining on the brick face after rain, or internal damp patches that appear after heavy rainfall. In older Yorkshire stone properties, you may also notice soft or sandy mortar that has lost cohesion. If you can see daylight through a joint from inside, repointing is almost certainly overdue.
Recent local work -
Not sure how bad it is?
If you're unsure whether the joints need attention, or if there's active damp inside and you're not certain of the cause, a Building Leak & Damp Inspection is the right starting point.