BUILDING INSPECTION GUIDE
Diagonal Wall Cracking
Diagonal cracking can be associated with movement within a building, particularly where cracks develop around doors, windows or other openings. The pattern, width and location of the cracking help provide context during a building inspection.
UNDERSTANDING THE DEFECT
What Can Diagonal Cracking Indicate?
Diagonal cracking commonly develops where stresses are concentrated within a wall. Openings such as doors and windows can be particularly susceptible because they interrupt the continuity of the wall.
Cracks may extend from the corners of openings or travel diagonally across wall finishes or masonry. Depending on the building, the cracking may be related to normal material movement, localised movement or broader movement within the structure.
The direction of the crack is useful information, but it does not establish the cause on its own. The surrounding building and site conditions also need to be considered.
WHAT WE CONSIDER
Signs That Help Put Diagonal Cracking in Context
Several related observations can help establish whether cracking appears localised or forms part of a wider building movement pattern.
Diagonal cracks extending from window or door corners can occur where stresses concentrate around the opening.
External cracking that follows brick or block joints can provide additional evidence of movement.
The visible width and length are considered together with the location and overall defect pattern.
Binding, sticking or distorted openings may indicate movement beyond the visible wall finish.
Uneven floors, cracked finishes or changes in level can provide further context where wall cracking is present.
Repaired or reopened cracks may indicate that movement or cracking has occurred previously.
POSSIBLE CONTRIBUTING FACTORS
Why Diagonal Cracking Can Develop
Diagonal cracking can develop for several reasons, including differential building movement, settlement, changes in supporting ground conditions, shrinkage and movement between different construction elements.
Soil moisture, drainage and nearby vegetation may also be relevant where they influence the ground supporting the building. In other situations, the cracking may be more closely related to local construction details or material movement.
Because different causes can produce similar-looking cracks, the broader pattern of visible defects is important when assessing the condition.
WHAT WE CHECK
Diagonal Cracking During a Building Inspection
Where diagonal cracking is identified, we consider the crack together with other accessible areas of the building and surrounding site.
The objective is to determine whether the defect appears isolated or whether additional visible conditions indicate a broader movement pattern.
PUTTING THE FINDING IN CONTEXT
The Pattern of Cracking Matters
A small isolated crack and a repeated pattern of diagonal cracking across several areas can have very different implications. The surrounding building conditions help determine what level of attention may be appropriate.
Where diagonal cracking is significant, widespread, displaced or associated with other signs of structural movement, further investigation by an appropriately qualified structural engineer or other relevant specialist may be recommended.