Every landed house cracks. Concrete shrinks as it cures, plaster moves differently to the block behind it, a house heats and cools daily in this climate, and materials that are bonded together but expand at different rates will eventually part somewhere. A house with no cracks at all is usually a house that was recently painted.

So the question is never "is there a crack". It is "is this crack telling me something is moving". Those are different questions with very different costs attached, and the difference is not decided by how alarming the crack looks.

What follows is how we read them on site, before an engineer is engaged and before anyone starts hacking. It is not a substitute for an assessment — where the answer matters, it is a Professional Engineer who makes the structural call, not a builder. But it will tell you which situation you are in and what to ask for.

The three questions that actually sort a crack

1. Where is it?

Location tells you more than width. A crack in a plaster skim on a non-loadbearing partition is a finishing issue. The same width crack running diagonally out of the corner of a window opening on a facade, or stepping through the mortar joints of a masonry wall, is a different conversation entirely.

The positions worth taking seriously in a landed house:

• Diagonally from the corners of door and window openings, especially where several openings in the same wall crack the same way. Openings are where a wall is weakest, so movement in the wall shows there first.
• Stepping through mortar joints in brick or block work, following the joints in a staircase pattern, usually widening toward one end.
• At the junction between an older house and a newer extension. Two structures of different age, different foundation and different stiffness, joined together — this is the single most common location for a genuinely structural crack in a Singapore landed house, and often the most benign in cause.
• On a beam or a column, rather than on the wall between them. Vertical cracks on a column or cracks near the ends of a beam are worth an engineer's eyes on principle.
• Along the underside of a slab, following a straight line — that line may be reinforcement, and rust-driven cracking is a maintenance problem that gets worse on a schedule of its own.
• Concentrated on one part of the house, particularly one corner, while the rest is clean.

2. Is it moving?

This is the question worth the most and it costs almost nothing to answer. A crack that has been there for fifteen years, is dirty inside, has been painted over twice and is still the same width is a historical crack. A crack that is clean-edged, sharp, and has opened since you last looked is an active one.

Monitoring is simple and it is what an engineer will want anyway:

• Photograph it with a rule or a coin against it, dated.
• Mark the ends with a fine pencil line and date them, so extension is visible.
• Repeat monthly for three months, in the same light.
• Note anything happening nearby — construction on the adjoining plot, excavation on the street, a drain repair, a period of unusually heavy rain.

Three months of dated photographs turns a subjective argument into evidence. If you are in a dispute with a neighbouring site, it becomes considerably more than that.

3. What else is happening in the house?

A single crack is a crack. A crack accompanied by other symptoms is a pattern, and the pattern is the diagnosis:

• Doors and windows that have started to bind or that no longer latch.
• Floor tiles lifting, drumming or tenting in a line.
• Gaps opening between skirting and floor, or between a wall and a ceiling.
• A floor that has begun to slope, testable with a marble or a spirit level.
• The same crack visible on both faces of the same wall.
• Cracks appearing at several points at once, over weeks rather than years.

Any two of those together with a crack moves this out of decorating and into assessment.

What usually causes the real ones

Differential settlement. Parts of the house settling by different amounts. Common where an extension sits on newer, shallower foundations beside an older house, and where the ground under one part of the plot behaves differently to the ground under another — which in Singapore is entirely normal, as we set out in soil conditions, clay, sand and groundwater. Where settlement is genuinely progressive, the remedy is at foundation level, which is the territory of underpinning a failing foundation.

Work done to the house. A wall removed without adequate propping or without a properly designed transfer, a beam undersized for what was actually put on it, an opening widened without trimming. This is a large share of what we are called to look at, and the crack is downstream of a decision made years earlier — the reason we go on about which walls in a landed house are load-bearing and about what column removal actually requires.

Water. Persistent moisture in a wall from a failed waterproofing detail or a leaking pipe corrodes reinforcement, and corroding steel expands and cracks the concrete around it. A crack with a rust stain, or a damp patch that reappears after every rain, is a water problem first and a structural one second — see waterproofing failure points.

Something happening next door. Excavation, piling or demolition on an adjoining plot. If this is your situation, dated photographs taken now are the most valuable thing you own, and a dilapidation survey should have been done before their works started.

Thermal and shrinkage movement. The commonest cause of all, and almost always cosmetic. Fine, stable, often in a straight run along a plastered surface or at the junction of two different materials.

What we would not do

Fill it and repaint, before knowing. Filling an active crack does not stop the movement; it hides it, and it destroys the evidence you would have used to prove when it started. Cosmetic cracks are filled after they are established as cosmetic, not before.

Inject resin because a product exists for it. Injection has real uses. It is not a diagnosis, and applied to a crack that is still moving it fails and leaves the cause untouched.

Accept "just settlement" as an answer without evidence. It is the phrase used for every crack by everyone who does not want to look further. Sometimes it is entirely correct. It is only worth anything when someone can say why.

Who should look at it, and in what order

1. You. Photograph and monitor. Three months of dated evidence costs nothing and changes every subsequent conversation.
2. An assessment, if the pattern warrants one. Where the structural question matters, a Professional Engineer makes that call. We work with an in-house architect and QP on submissions, and we are clear about the boundary: we build, and the engineer determines what the structure is doing. Any builder who tells you a crack is structural or not, without an engineer, is guessing at your expense. The role is set out in what a QP does on a landed A&A project.
3. Then the works, scoped from what the assessment actually found — and where structural alteration or repair is involved, carried out by a licensed builder with the right submissions in place. We hold a BCA General Builder Class 2 (GB2) licence and do that work in-house.

Doing those in the other order is how owners end up paying for a repair to a symptom while the cause carries on.

If you are buying the house

Cracks at a viewing are worth reading rather than fearing. Fresh paint over one wall in an otherwise tired house is worth a question. Doors that bind, a floor that slopes, tiles drumming underfoot, and any crack at the junction with an extension all deserve to be raised before the option, not after — as does the approval history of the extension itself, which is a separate check we cover in reading the A&A approval history.

Send us the photographs

If you have a crack that is bothering you, send photographs with something for scale, say roughly how old the house is, whether anything has been built or removed, and whether anything is happening on the plots either side. We will tell you plainly whether it looks like a finishing matter or something that needs an engineer — and if it is the second, we will say so rather than quote you for a repair.

WhatsApp 9107 2601 about cracks in a landed house →