A crack in a wall always causes worry: is it just a plaster defect, or a warning that the building is moving? In fact building cracks come in several types; some are superficial, caused by plaster shrinkage or thermal expansion of materials, and some warn of a problem in the frame or foundations that must be dealt with immediately. The common mistakes are panicking over every hairline crack, or covering a dangerous crack with filler and paint. This guide explains the types of cracks, when to call an engineer immediately, how the engineer assesses them, their common causes, and correct repair methods.
Types of Cracks
| Type | Usual appearance | Potential severity |
|---|---|---|
| Hairline cracks in plaster | Fine and random | Usually superficial, due to shrinkage |
| Where a wall meets a column or beam | A straight line along the junction | Usually due to different materials; needs assessment |
| Diagonal near doors and windows | At an angle from the corners | May indicate settlement; needs inspection |
| In columns or beams | Horizontal or diagonal, or with exposed rebar | Requires urgent structural inspection |
| Widening over time | Width increases | A sign of continuing movement |
Common Causes of Cracks
- Shrinkage of plaster and concrete as they dry.
- Thermal expansion with Riyadh's large temperature swings.
- Foundation settlement due to weak soil or poor replacement. Read: The soil investigation report.
- Water leaking into the soil, or corroding rebar.
- Excess loads from unplanned additions. Read: Structural assessment for an additional floor.
- Neighbouring works: nearby excavation or demolition. Read: Excavation shoring.
When Should You Call an Engineer Immediately?
- Cracks in load-bearing elements: columns, beams and slabs.
- Exposed rebar or falling concrete.
- Doors and windows that suddenly start sticking.
- Tilting or sinking floors.
- A crack that widens week after week.
In serious cases read: Buildings at risk of collapse.
How to Monitor a Crack Yourself
- Draw two marks at the ends of the crack and write the date.
- Photograph the crack with a ruler or pen for scale.
- Re-measure every two weeks; any widening calls for an engineer.
How Does the Engineer Assess Cracks?
- Recording width, length and direction, and monitoring change over time.
- Reviewing the drawings and the soil report if available.
- Concrete tests where needed.
- Identifying the cause before proposing a solution.
Repair
Repair treats the cause, not just the crack. The Saudi Building Code includes a code for repair, rehabilitation and strengthening of existing concrete structures (SBC 310). According to Balady, the restoration permit does not cover changing structural elements. Read: The restoration permit and Structural assessment before restoring old buildings.
Cracks When Buying
If cracks appear in a property you intend to buy, ask for an inspection before signing. Read: Pre-purchase building inspection.
Frequently Asked Questions
Are hairline cracks dangerous?
Usually not, but monitor them; if they widen or recur, consult an engineer.
Should I cover the crack with filler?
Not before knowing the cause, because covering it hides how the problem develops.
Are cracks in a new building normal?
Hairline plaster cracks are common; structural ones call for review with the contractor and supervisor.
Who pays for repairs if the cause is a neighbour's excavation?
That requires documentation and an engineering report. Read: Engineering reports in disputes.
How long does a structural inspection take?
It depends on the building's size and the need for tests; urgent cases are prioritised.
How Abak Engineering Consultancy Helps
Abak is an accredited engineering office in Riyadh that inspects cracks and identifies their causes, prepares structural inspection reports and repair designs to the code, and supervises the repair. See our structural inspection reports service, or contact us.
Regulatory information is based on the Balady platform and the Ministry of Municipalities and Housing, and procedures may be updated by the competent authority. Last reviewed: October 2026.