What Causes Wall Cracks in Dubai Homes, and When to Worry

Most wall cracks in Dubai homes are caused by thermal movement, plaster shrinkage and minor foundation settlement, not structural failure. As a working rule, a crack narrower than 1mm that has not changed in six months is cosmetic. A crack wider than 5mm, one that runs diagonally from a window or door corner, or one that is visibly widening month to month needs a structural engineer, not a painter.

The difficulty is that a 0.4mm hairline crack and a 6mm settlement crack look almost identical under a coat of matte emulsion. Homeowners either panic over harmless shrinkage or paint over something that is quietly getting worse.

This guide gives you the measurement thresholds professionals actually use, the crack patterns specific to Dubai’s blockwork-and-render construction, what repair genuinely costs here, and who is legally liable to pay for it, including under Dubai’s new building safety law.

Table of Contents

Key Takeaways

• Width Is the First Filter: Under 1mm is almost always cosmetic. Between 1mm and 5mm is usually repairable decoration work. Over 5mm, or any crack that is growing, warrants an engineering assessment.
• Direction Tells You the Cause: Straight vertical or horizontal lines along wall-ceiling junctions are material movement. Diagonal and stair-step cracks running from opening corners point to differential settlement.
• Dubai’s Climate Does Specific Damage: A 25°C daily surface swing on external walls, chilled interiors at 22°C, and coastal salt-laden groundwater all drive movement that simply doesn’t exist in temperate climates.
• Most “Recurring” Cracks Were Never Repaired: Filler alone doesn’t work. The crack has to be raked out, bridged with mesh, and finished with a flexible system.
• Typical Repair Cost: Cosmetic repair in a Dubai villa typically runs AED 35 to 55 per m² for full plaster and finish work, with whole-villa repaint and prep commonly landing between AED 3,500 and AED 6,000 for a three-bedroom home.
• You May Not Be the One Who Pays: Structural defects carry a 10-year strict liability on the contractor and engineer under UAE law. Rented properties default to the landlord under Dubai’s tenancy law.

Common Causes of Wall Cracks in Dubai Homes

Wall cracks in Dubai are caused by four mechanisms, in descending order of frequency: plaster and render shrinkage, thermal expansion and contraction, moisture and salt movement, and foundation settlement. Poor workmanship accelerates all four.

Here is what each one actually does to your walls.

Foundation Settlement and Dubai’s Ground Conditions

Every building settles. A villa handed over in the last three to five years is still finding its equilibrium, and fine cracks at wall-ceiling junctions during that period are normal. What matters is whether the settlement is uniform (the whole structure sinking evenly, which is harmless) or differential (one part sinking faster, which is not).

Dubai’s ground makes differential settlement more likely than in many cities. Large parts of the emirate sit on loose aeolian sand, and coastal and low-lying areas sit on sabkha: salt-flat deposits of thin, alternating layers of sand, clay and evaporite minerals over a shallow water table. Research on sabkha soils in the Gulf describes them as unconsolidated and heterogeneous, bathed in highly concentrated subsurface brines, with cemented and uncemented layers stacked unpredictably. That cementation comes from salt. Introduce fresh water, whether from a leaking irrigation line, a burst pipe or an undrained pool backwash, and the salt dissolves, the bond fails, and a void opens under the slab.

Villas in newer, lower-lying developments are more exposed to this than older inland communities. That doesn’t make them defective; it makes drainage discipline more important.

Thermal Expansion: The 25°C Daily Swing

This is the single most underestimated cause in Dubai. Concrete, blockwork, cement render and gypsum all expand at different rates when heated, and Dubai heats them hard.

Ambient temperature in the emirate ranges from winter lows in the low teens to summer highs above 45°C, with the official record standing at 52.1°C. But ambient air temperature understates the problem. A south-facing external render surface in July absorbs solar radiation and reaches surface temperatures well above air temperature during the day, then radiates that heat away overnight.

Now add air conditioning. The internal face of that same wall sits at a constant 22 to 24°C for eight months of the year. You have a wall with a permanent thermal gradient across its thickness, cycling daily. The render expands, the blockwork behind it expands less, the concrete column beside it expands differently again. The crack forms at the weakest line, which is almost always the junction between two different materials.

That is why so many Dubai cracks appear as dead-straight lines following the outline of a concrete column, beam or lintel behind the plaster. The crack is tracing a material boundary.

Humidity, Salt and Moisture Movement

Dubai’s annual average relative humidity of around 59%, which peaks near 65% in winter and spikes far higher on coastal summer nights, pushes moisture into wall build-ups continuously. Three things follow.

Condensation behind finishes. Cold internal surfaces meeting humid air produce interstitial condensation. Trapped moisture softens gypsum skim, breaks the paint bond, and shows up as blistering and map cracking before it shows up as a crack.

Salt crystallisation. Where saline groundwater or wind-borne salt reaches masonry and then evaporates, salts crystallise inside the pores. Crystal growth exerts real pressure, enough to spall render and open surface cracks from within. You’ll usually see white efflorescence powder alongside it.

Sulphate attack on concrete. Gulf groundwater carries gypsum, anhydrite and sodium chloride. Sulphate ions reacting with hydrated cement compounds form expansive products such as ettringite, and the resulting internal pressure causes cracking, spalling and loss of strength. This is why sulphate-resisting cement and protective coatings are specified in foundations here. It’s also why a crack in a ground-floor wall near a persistently damp patch deserves more attention than the same crack upstairs.

The April 2024 floods made this worse for thousands of homes. Water that entered wall cavities and screeds took months to dry, and a lot of 2025 to 2026 cracking traces directly back to that event.

Poor Plastering and Workmanship

The most common cause of cracks in a brand-new villa has nothing to do with the ground. It’s the render.

Cement-sand plaster shrinks as it cures. Applied too thick in one pass, mixed too wet, or, most often in Dubai, allowed to dry too fast in summer heat without proper curing, it shrinks unevenly and cracks in a fine random web. Dubai Municipality carried out more than 25,000 construction field inspections in the first half of 2025 alone, a 36% year-on-year increase, which reflects how seriously build quality is now being policed. But inspection regimes catch systemic failures, not every over-watered plaster mix on every villa.

Three specific workmanship failures produce most avoidable cracks:

• No mesh at material junctions. Where blockwork meets a concrete column or beam, fibreglass or galvanised mesh should bridge the joint before rendering. Skipping it guarantees a crack within two summers.
• Chasing without proper making good. Electrical and plumbing chases cut into blockwork and filled with weak mortar crack along their exact route. If your crack runs in a suspiciously neat vertical line down to a socket, this is why.
• Overloaded gypsum partitions. Lightweight partitions taking loads they weren’t designed for crack at board joints and around door heads.

Vibration From Neighbouring Construction

In actively developing communities, piling, excavation and heavy plant movement next door transmit vibration through the ground. This rarely causes structural damage to a sound villa, but it readily opens existing hairline cracks and shakes loose already-debonded render. If cracks appeared within weeks of a neighbouring plot breaking ground, photograph and date everything. That documentation matters if you later raise a claim.

Types of Cracks in Walls and What Each One Means

The pattern of a crack is more diagnostic than its size. Vertical and horizontal cracks along junctions are usually movement between materials. Diagonal and stair-step cracks are usually the ground. Random web-like cracks are usually the finish itself.

Hairline Cracks (Under 1mm)

Fine, shallow, often only visible at an angle to the light. Typically shrinkage in the skim coat or paint film, or early thermal movement. Almost never structural on their own. The exception: a single hairline crack that reappears in the identical position after every repaint is telling you there is movement underneath that filler cannot absorb.

Vertical Cracks

Straight vertical cracks at wall-to-wall corners, beside door frames, or tracing the edge of a concrete column are classic differential movement between dissimilar materials. Generally cosmetic when narrow and stable.

Vertical cracks become a concern when they are wide at one end and narrow at the other (tapered), when they run continuously through several courses of blockwork, or when the same crack appears on both faces of the same wall.

Horizontal Cracks

Treat these with more caution than any other type. A horizontal crack along a mortar bed joint, particularly one accompanied by any bulge or lean in the wall, can indicate lateral pressure, a failed lintel, or corrosion of embedded reinforcement.

Corrosion is worth explaining, because it’s common here. Steel reinforcement rusts and expands to several times its original volume. That expansion cracks the concrete cover off in a straight line above the bar, often with rust staining and eventual spalling. In Dubai’s chloride-rich coastal environment this is a known durability issue, and it needs an engineer. Patching over it traps the problem and accelerates it.

Stair-Step (Diagonal) Cracks

Cracks that follow the mortar joints in a diagonal staircase pattern, or run at roughly 45 degrees from the corner of a window or door, are the classic signature of differential settlement. One part of the structure is moving relative to another, and the wall is tearing along its weakest path.

Not every stair-step crack is an emergency. A narrow, stable one in a fifteen-year-old villa may be a historic movement that finished a decade ago. But this is the pattern that most often justifies professional assessment, especially if it is wider than 3mm, if it appears on an external wall, or if doors and windows in that area have started sticking.

Map Cracking (Crazing)

A fine, random, web-like network across a wall surface, like a dried riverbed. This is shrinkage in the render or skim coat, caused by poor mix, excess water, or rapid drying in heat. It is a finish defect, not a structural one, but it needs the affected coat removed rather than filled, because filling a crazed surface just produces a crazed surface with filler in it.

Junction Line Cracks

Long, clean, straight cracks exactly along wall-ceiling junctions, or where gypsum board meets plastered blockwork. Extremely common in Dubai and almost always benign thermal and material movement. These are the cracks that reappear after every repaint if they’re rigidly filled instead of treated with a flexible bridging system.

Comparison Table of Crack Type, Likely Cause and Severity

Table 1: Crack Type, Cause and Severity

The Professional Classification: BRE Digest 251

Surveyors and structural engineers worldwide classify crack damage using BRE Digest 251, published by the UK’s Building Research Establishment after a study of 130 properties affected by subsidence. It grades visible damage from category 0 to category 5. Per BRE, categories 0 to 2 are aesthetic issues requiring only redecoration, categories 3 and 4 are serviceability issues affecting weathertightness and the operation of doors and windows, and category 5 presents stability issues requiring structural intervention.

Table 2: BRE Digest 251 Damage Categories

One caveat the Digest itself stresses, and which most online guides omit: the classification is based on ease of repair, not width alone. Several 2mm cracks in a single wall, combined with sticking doors and a visible lean, can place damage in a higher category than one isolated 6mm crack. Width is your starting point, not your verdict. For a fuller technical overview of movement mechanisms, the Designing Buildings reference on cracking and building movement is a solid, non-commercial resource.

When a Crack Is Cosmetic vs Structural

A crack is cosmetic if it is narrow, stable, confined to the finish, and unaccompanied by any other symptom. It is potentially structural if it is wide, growing, visible on both faces of a wall, or appears alongside sticking doors, sloping floors, or a wall that no longer looks plumb.

The crack itself is only one data point. What tells you the truth is the cluster of symptoms around it.

The Ten-Minute Check You Can Do Yourself

Work through this before calling anyone.

• Measure it. Use a crack gauge card, or a ruler against a photograph. Record the width at the widest point, in millimetres. “About the width of a hair” is not a measurement.
• Check both faces. Go to the other side of the wall. A crack visible on both faces has gone through the full thickness of the wall, which raises it from a finish defect to a wall defect.
• Check if it’s tapered. Wider at the top than the bottom, or vice versa? Tapering indicates rotational movement, which is more significant than a parallel-sided crack.
• Try the doors and windows nearby. Sticking, binding, uneven gaps around frames, or a door that swings open on its own all suggest the opening has racked out of square.
• Roll a marble. On a tiled ground floor, a marble that consistently runs to one corner of a room indicates a sloping slab.
• Look for water. Damp patches, white powdery efflorescence, bubbling paint, mould, or rust staining. Moisture changes both the diagnosis and the repair sequence entirely.
• Date it. Draw a pencil line across each end of the crack, write today’s date beside it, and photograph it with a ruler in frame.

Monitor Properly Before You Panic

A single measurement tells you nothing about whether movement is active. Structural assessment depends on change over time.

Fit a telltale crack monitor, a two-part acrylic gauge screwed either side of the crack, or use the pencil-mark-and-photograph method. Re-measure monthly. BRE’s guidance on subsidence cases recommends measurement series over six months to a year to establish whether movement is progressive, seasonal, or finished.

If the crack hasn’t moved in six months, you have a historic crack. Repair it cosmetically and move on. If it has widened measurably, you have active movement and you need a licensed engineering office.

Call an Engineer Now, Not in Six Months, If:

• The crack is wider than 15mm, or has exceeded 5mm and is still growing.
• Any crack runs horizontally along a bed joint, especially with a bulge or lean.
• Multiple diagonal cracks have appeared across several rooms in a short period.
• A wall, column or floor is visibly out of plumb or level.
• You can see exposed or rusting reinforcement, or concrete is spalling off in sheets.
• Cracks appeared suddenly after flooding, a major leak, or adjacent excavation.
• Doors and windows across the property have become difficult to close.

Anything on this list is a matter for an engineering office licensed by Dubai Municipality, not a maintenance contractor. If the assessment clears the structure, the repair itself is then straightforward, and that’s where a qualified handyman and maintenance team takes over.

How Cracks Are Repaired Properly

Proper crack repair means opening the crack up, bridging it so it cannot re-form along the same line, and finishing with a system that can flex. Smearing filler over a closed crack and painting it is not a repair. It is a delay.

That distinction explains why so many Dubai homeowners repaint every two years and watch the same crack reappear in the same place every time.

Hairline Crack Repair (Under 1mm)

The sequence that actually holds:

• Rake the crack open into a shallow V-groove using a scraper or utility blade. You need a channel that filler can key into, not a closed hairline it can only sit on top of.
• Vacuum and dampen. Dust prevents adhesion. In Dubai’s heat, lightly misting the substrate stops the filler drying before it cures properly.
• Apply a flexible acrylic or elastomeric filler in two thin passes rather than one thick one. Rigid gypsum-based filler in a thermally active wall will simply crack again.
• Bridge it with mesh where the crack follows a junction between different materials. Self-adhesive fibreglass tape bedded into the filler spreads future movement across a wider area instead of concentrating it on one line.
• Sand flush, spot-prime, then paint across the full wall, never a patch. Touch-up patches sheen-flash in Dubai’s strong natural light and look worse than the crack did.

Moderate Cracks in Render (1 to 5mm)

Same principle, larger scale. The affected render is cut back to sound material. Tap it with a knuckle; a hollow sound means it has already debonded and must come off. The area is re-rendered in a compatible mix, mesh-reinforced across the repair zone, cured properly rather than allowed to flash-dry, and left to stabilise before any decoration. The curing step is the one contractors skip in summer, and it is the reason the repair fails.

Once the substrate is sound, the finish system matters as much as the filler. Different surfaces, sheens and room conditions call for different approaches, which we cover in detail in our guide to painting techniques for Dubai interiors.

Structural Crack Repair

This is engineer-directed work and the method depends entirely on the diagnosis:

• Epoxy resin injection: for cracks in structural concrete, where the resin restores monolithic action across the crack. Only appropriate where movement has stopped.
• Helical bar stitching: stainless steel bars bonded into slots cut across the crack in blockwork, re-tying the masonry.
• Movement joint installation: where the real problem is that the structure had nowhere to expand, a proper joint is cut in and sealed so future movement happens where you want it.
• Underpinning or ground stabilisation: for confirmed differential settlement. Rare in residential Dubai, expensive, and never the first answer.
• Concrete repair for corrosion: breaking out to expose the reinforcement, treating or replacing the steel, and reinstating with a protective repair mortar.

Critically, the water source is always fixed first. Repairing a crack caused by a leak without fixing the leak wastes the entire job.

Finishing: Why the Paint System Matters Here

A repaired wall in Dubai needs a coating system that tolerates movement and blocks moisture. Elastomeric and flexible masonry coatings on exteriors, moisture-tolerant systems in bathrooms and kitchens, and proper primer on every patched area. Getting the preparation and specification right is what turns a repair into a finish that survives a summer, which is the core of professional painting services in Dubai.

Wall Crack Repair Cost in Dubai

Cosmetic crack repair in Dubai is typically bundled into plastering and painting rates rather than priced per crack. Expect roughly AED 35 to 55 per square metre for a full plaster cycle, and AED 10 to 25 per square metre for interior painting including labour and materials.

The table below reflects indicative 2026 market ranges. Actual quotes vary with access, ceiling height, occupancy and finish specification.

Table 3: Wall Crack Repair Cost Guide

Two things drive the final number more than anything else.

Surface preparation is the real cost. On a villa in the seven-to-fifteen-year bracket, which covers much of Arabian Ranches, The Springs, The Meadows, Mirdif and Al Barsha, settlement cracking around openings and areas of hollow render are routine. Preparation can account for a substantial share of total project cost, and it is the line item that cheap quotes quietly delete.

A suspiciously cheap quote is a quote without preparation. If one contractor is 40% below the others, they are applying a single thin coat over unprepared walls. In this climate that fails within a season, and you pay twice.

For whole-property work where cracking is widespread enough that patch repair no longer makes sense, it’s usually more economical to fold it into planned renovation and maintenance work than to treat each wall as a separate call-out.

Who Pays for Wall Crack Repairs in Dubai

If you own a villa under ten years old and the crack is structural, the contractor and engineer may be liable, not you. If you rent, the default position under Dubai law puts maintenance on the landlord. Both points are worth knowing before you spend your own money.

Decennial Liability: The 10-Year Structural Warranty

Under Articles 880 to 883 of the UAE Civil Code, the contractor and the supervising engineer are jointly liable to the employer for ten years from delivery of the works for total or partial collapse, and for any defect that threatens the stability or safety of the structure.

Three features make this unusually strong protection:

• It is a strict liability. You do not have to prove fault or negligence, only that the structural defect exists and falls within the ten-year window.
• It survives ground defects. Liability applies even where the defect arises from a fault in the land itself, and a supervising engineer or contractor cannot contract out of it or limit it.
• There is a hard deadline. A claim must be brought within three years of the defect being discovered.

The limit matters too: UAE courts have consistently confined this regime to collapse and to defects genuinely threatening structural soundness. Cosmetic cracking does not qualify. Hairline shrinkage cracks fall under the shorter contractual defects liability period, commonly twelve months from handover, rather than the ten-year regime. Report them during the snagging window.

If You Rent: Article 16

Under Article 16 of Law No. 26 of 2007 regulating the relationship between landlords and tenants in Dubai, unless the parties have agreed otherwise, the default sits with the landlord for property maintenance and for repairing any defect or damage affecting the tenant’s intended use.

Two practical points follow. First, the default sits with the landlord for structural cracking, water ingress and weather-related damage not caused by the tenant. Second, the phrase “unless otherwise agreed” means your tenancy contract can and often does reallocate minor repairs to you, usually via a cost threshold. Read that clause before you argue. Unresolved disputes go to the Rental Disputes Centre.

Dubai Law No. 3 of 2026: The New Obligation Owners Are Missing

This is the development most Dubai homeowners haven’t caught up with yet.

In January 2026, Law No. 3 of 2026 on the quality and safety of buildings in the Emirate of Dubai was issued. It applies to all buildings across Dubai, including private development zones and free zones such as the DIFC, and including buildings constructed before the law existed.

What it means for a homeowner with a cracked wall:

• Owners must obtain a Quality and Safety Certificate, issued only after a licensed engineering office conducts a comprehensive inspection and assessment of the building’s structural and technical condition.
• Owners must carry out periodic maintenance for buildings under 20 years old, and must rectify any defects that threaten structural safety, lives, property or neighbouring buildings.
• Certificate validity is 10 years for buildings under 40 years old, and five years for buildings of 40 years or more, renewable.
• Penalties run from AED 100 to AED 1,000,000, doubling up to AED 2,000,000 for repeat offences within two years. Authorities may also suspend permits and halt transactions with the Dubai Land Department, including lease certifications.
• Owners, contractors and engineering offices were given one year from the law’s effective date to comply.

The practical takeaway: a structural crack you’ve been ignoring is no longer only a maintenance question. It sits inside a compliance framework with a documented inspection trail attached to your property. Fixing it properly, with records, is now part of protecting the asset’s transactability.

How to Stop Cracks Coming Back

Most recurring cracks in Dubai homes are preventable. The measures that actually work:

• Fix leaks immediately. AC condensate lines, irrigation, pool plant and bathroom waterproofing failures cause more crack damage here than settlement does.
• Keep interior temperature stable. Setting the AC to 24°C rather than swinging between 18°C and off reduces the thermal cycling your walls experience.
• Ventilate. Extract properly from bathrooms and kitchens so moisture leaves the building instead of condensing inside wall build-ups.
• Specify mesh reinforcement at every material junction in any renovation work. Non-negotiable.
• Insist on curing. Any new plaster or render in summer must be kept damp while it cures. Ask your contractor how they plan to do it.
• Repaint on a schedule, not on failure. Exterior coatings in Dubai’s UV and salt exposure have a working life of a few years. Recoating before the film fails keeps water out of the substrate.
• Snag properly at handover. Document every crack with photographs, measurements and dates during the defects liability period, while someone else is still contractually obliged to fix it.
• Maintain drainage away from the villa. Standing water against a foundation in sabkha-influenced ground is the one condition you genuinely want to avoid.

Frequently Asked Questions

Are hairline cracks in walls normal in Dubai?

Yes. Hairline cracks under 1mm are normal and expected in Dubai homes, particularly in properties under five years old. They result from plaster shrinkage and thermal movement between materials, not structural failure. They become worth investigating only if they widen measurably over six months, reappear in the identical position after every repaint, or are accompanied by sticking doors or damp patches.

How wide does a crack have to be before it’s structural?

There is no single width that automatically means structural, but the practical thresholds are: under 1mm is cosmetic, 1 to 5mm is repairable decoration work, 5 to 15mm affects serviceability and needs professional opening up, and above 15mm requires structural assessment. BRE Digest 251 stresses that ease of repair, not width alone, determines severity. Several 2mm cracks with distorted door frames is a more serious situation than one isolated 6mm crack.

Why do the same cracks keep coming back after painting?

Because filler was applied without addressing the movement causing the crack. A rigid filler smeared over a closed hairline has nothing to key into and no capacity to flex, so the wall moves in the next thermal cycle and the crack re-forms along the identical line. A lasting repair requires raking the crack into a V-groove, bedding mesh tape across it where it crosses a material junction, and using a flexible acrylic or elastomeric filler.

Do wall cracks mean my Dubai villa’s foundation is failing?

Almost never. The overwhelming majority of wall cracks in Dubai villas are finish defects and thermal movement, not foundation problems. Genuine foundation issues announce themselves with a cluster of symptoms: diagonal or stair-step cracking from opening corners across multiple rooms, doors and windows binding throughout the property, visibly sloping floors, and cracks that are measurably widening month to month. A single crack with none of those companions is not a foundation failure.

Should I repair cracks before selling or renting out my property?

Yes, and repair them properly rather than cosmetically. Under Dubai Law No. 3 of 2026, buildings require a Quality and Safety Certificate based on a licensed engineering inspection, and authorities can halt transactions and lease certifications with the Dubai Land Department where violations are outstanding. Beyond compliance, a buyer’s snagging inspector will find a filled-over structural crack, and finding it late costs far more in negotiation than fixing it early.

Who pays for wall crack repairs, the landlord or the tenant?

Under Article 16 of Dubai’s Law No. 26 of 2007, the landlord is responsible by default for maintenance and for repairing defects affecting the tenant’s intended use of the property, unless the tenancy contract states otherwise. Structural cracking, water ingress and weather-related damage not caused by the tenant fall to the landlord. Many Ejari-registered contracts reassign minor repairs below a stated value to the tenant, so check your specific clause before raising it.

Can I claim wall cracks against my developer’s warranty?

Possibly, depending on severity and timing. Structural defects threatening the stability or safety of the building carry strict joint liability on the contractor and supervising engineer for ten years from delivery under Articles 880 to 883 of the UAE Civil Code, with a three-year limitation period from the date you discover the defect. Cosmetic cracking is excluded from that regime and falls instead under the contractual defects liability period, usually twelve months from handover. Document cracks with dated photographs and measurements from day one.

Does Dubai’s heat really cause wall cracks, or is that an excuse?

It genuinely does. Dubai’s ambient temperature ranges from winter lows in the low teens to summer highs above 45°C, and external render surfaces exposed to direct sun run considerably hotter than air temperature. Combine that with an air-conditioned interior held at 22 to 24°C and you have a permanent thermal gradient across the wall, cycling daily for months. Concrete, blockwork and render expand at different rates under that load, and cracks form at the junctions between them. It is a real mechanism, not a contractor’s excuse, but it should never be used to explain away a diagonal crack from a window corner.

How long should I monitor a crack before deciding?

Six months minimum, twelve months ideally. Structural assessment depends on whether movement is active, and a single measurement cannot tell you that. Fit a telltale crack gauge or mark each end of the crack in pencil with the date, photograph it monthly with a ruler in frame, and record the width in millimetres. If there is no measurable change after six months, the movement is historic and cosmetic repair is appropriate. Any measurable widening means active movement and warrants a licensed engineering office. Don’t wait six months if the crack is horizontal, over 15mm, or accompanied by a bulging wall. Those need attention immediately.