Concrete Crack Detection Singapore — Drone Facade Crack Survey & Mapping

What Is Concrete Crack Detection?

Concrete crack detection is the systematic survey of a building's external concrete surfaces to find, record and characterise every crack in the facade — where it runs, how wide it is, what pattern it forms, and what that combination reveals about the concrete beneath. On a facade a crack is never just a cosmetic blemish. It is a piece of evidence. The same visible line can mean nothing more than surface shrinkage, or it can be the outward sign of corroding reinforcement, structural overload or building movement. The purpose of detection is to read that evidence correctly and separate the harmless cracks from the ones that demand action.

In Singapore, crack detection sits at the heart of the mandatory Periodic Facade Inspection (PFI) regime under the Building Control Act, which requires the full external facade of qualifying buildings to be professionally examined at set intervals. Cracks are one of the most common findings on any concrete or rendered facade, and how they are recorded and graded shapes the entire inspection outcome. A crack that is mapped, measured and correctly attributed to a cause lets a competent person make a defensible severity call; a crack that is simply noted as "present" does not.

Cracks matter because they operate on two timescales at once. In the short term a wide or moving crack can be an immediate warning sign of a structural problem. In the long term even a fine, stable-looking crack is a durability threat, because any crack that admits water starts a slow chain of hidden reinforcement corrosion that eventually leads to concrete spalling. Good crack detection captures both dimensions.

Crack Types and What Causes Them

Not all cracks are equal, and the single most useful thing a crack survey does is distinguish them by cause. The width, direction, pattern and location of a crack together point to why it formed — and therefore how seriously it should be treated. The broad divide is between non-structural cracks, which affect durability and appearance, and structural cracks, which signal that an element is stressed beyond what it should carry and which require a structural engineer's assessment.

The single most important distinction for facade safety is corrosion-induced cracking. A crack that runs straight and parallel to a rebar line, often with a rust stain bleeding from it, is the early stage of the process that ends in spalling. Catching it while it is still a crack — before the cover blows off — is the difference between a minor repair and a Category 3 hazard.

Why Crack Width and Pattern Matter

A crack's width is one of the strongest clues to its severity. Fine hairline cracks are typically shrinkage or crazing and are usually a durability rather than a stability concern. Wider cracks, cracks that open progressively along their length, and cracks that clearly follow a load or rebar line carry more weight in the competent person's grading. But width alone is never the whole story — a narrow crack in the wrong place, such as one tracking a reinforcement bar or crossing a construction joint, can matter far more than a wider but stable shrinkage crack elsewhere.

Pattern is equally telling. A diffuse web of fine lines reads as crazing; a set of parallel straight cracks reads as corrosion following the rebar grid; a single diagonal crack near a support reads as a possible shear or settlement issue. Recording width and pattern together is what lets an inspection move from "there are cracks" to a graded, actionable finding.

The reason width matters even for fine cracks is water. Any crack that admits rainwater feeds moisture, oxygen and airborne chlorides to the reinforcement, and that is precisely what drives the corrosion cycle. This is the mechanism that links cracks directly to spalling: a crack lets water in, the rebar corrodes and swells, and the expanding rust eventually forces the concrete cover off the face of the building. Detecting and sealing cracks early interrupts that chain before it becomes a debris hazard.

How Drone Crack Detection Works

We survey facades under BCA's TR 78 technical reference for drone-based facade inspection, which sets the camera, flight and reporting standards a compliant survey must meet. A drone flies pre-planned paths across every elevation at a consistent standoff distance, so image scale and overlap stay uniform from the podium to the crown of the building and no run of wall is skipped.

High-resolution visual capture is the primary tool. It resolves cracks down to fine widths across the whole facade, and because the imagery is captured at a known scale, crack width and length can be estimated directly from the images rather than guessed. Each crack is then geo-tagged and mapped to a facade grid and element reference, so a finding can be returned to precisely on the building. Where we survey the same facade again on a later cycle, comparing the maps shows whether a crack is active — widening or lengthening — or dormant and stable, which is one of the most valuable pieces of information for grading.

Radiometric thermal imaging runs alongside the visual survey and adds what the eye cannot see. Cracks with active moisture movement behind them — and water tracking into the substrate through a crack or joint — register as distinct thermal patterns, flagging which cracks are wet and therefore driving corrosion. The advantages over rope access are decisive:

• Complete coverage — every square metre of every elevation is imaged, not just the vertical drop-lines an abseiler can reach.
• Scale-calibrated widths — cracks are measured from imagery captured at a known standoff, giving consistent, comparable data across the whole facade.
• Active-vs-dormant tracking — repeat surveys reveal whether cracks are growing, which width alone cannot tell you.
• Traceable evidence — every crack is geo-tagged and mapped, giving your competent person a precise, auditable record for the BCA submission.

After capture, the imagery is assembled into a full facade mosaic. Each crack is annotated, described by type and width, located to an element reference, and compiled into a data package your competent person uses to produce the professional assessment and PFI report.

Cracks We Detect and Map

Our surveys are structured around the specific ways concrete facades crack. Each is identified, imaged, width-estimated and mapped to a facade grid for your competent person to classify.

Cracks Under Singapore's PFI Regime

Under the Building Control Act, buildings more than 13 metres tall that obtained their Temporary Occupation Permit more than 13 years ago must undergo periodic facade inspection every 7 years. Cracks are a core finding in almost every one of those inspections, and how they are graded drives the outcome. When BCA issues a facade inspection order, the appointed competent person must record and classify every significant crack across the facade.

Crack findings are classified using BCA's three-category system. Minor, stable shrinkage and hairline cracks are typically Category 1 (monitor). Progressive cracking, active movement and cracks admitting water usually fall into Category 2 (repair within a set timeframe). Corrosion-induced cracking that is breaking up the cover, and structural cracks that threaten load capacity or falling debris, escalate to Category 3 — immediate rectification and, where required, protective canopies. Because corrosion and structural cracks are the ones that escalate, detecting them early is the most cost-effective, least-disruptive point at which to act: sealing or repairing a crack is far cheaper than replacing spalled concrete once the cover has come off.

How Drone Detection Fits With Close-Range Testing

We are honest about what a drone survey does and does not replace. A drone is unmatched for coverage and triage: it maps every crack across the whole facade, estimates widths consistently, and prioritises which cracks matter — turning an entire building into a ranked, evidence-backed list of findings in a fraction of the time and risk of rope access. That map tells the inspection team exactly where to concentrate.

What it does not do is replace direct measurement at the crack. Confirming the precise width of a borderline crack, gauging its depth, or establishing whether it is genuinely moving over time is done during close-range inspection using crack-monitoring gauges, crack-width rulers and tactile checks at the specific points the drone has already flagged. The two work together: the drone finds and prioritises every crack; the competent person's close-range testing confirms movement and depth on the handful that need it. This is a far more efficient and complete approach than sending inspectors to check the facade blind.

Why Choose SG Drone Inspections

We are a specialist drone facade inspection provider in Singapore, focused on delivering the accurate, fully-mapped crack data that competent persons need to grade a facade with confidence.

Frequently Asked Questions