Cracks appearing above windows and doors are commonly found during building inspections throughout Melbourne.
Sometimes the cracking is relatively minor. In other cases, it can indicate foundation movement, movement of the masonry, problems with steel lintels or other building defects that require further investigation.
If you have noticed a diagonal, stepped, horizontal or vertical crack around a window or door, simply filling the crack may not solve the problem.
The important question is:
Why has the crack developed in the first place?
Why Do Cracks Commonly Appear Around Windows and Doors?
Windows and doors create openings in a wall, and these openings can become locations where stresses within the building are concentrated.
The masonry above an opening must also be adequately supported, generally by a lintel.
When movement occurs within the building or the support above an opening deteriorates, cracking may become visible around the corners of windows and doors.
This is why building inspectors pay particular attention to cracks around openings when assessing a property.
1. Foundation and Footing Movement
One possible cause of cracking around windows and doors is movement of the building’s foundations or footings.
If one section of a house moves differently from another, stresses can be transferred through the walls.
Because window and door openings interrupt the continuity of the wall, cracking may develop from the corners of these openings.
Diagonal or stepped cracks extending away from a window or door can sometimes be associated with this type of movement.
However, the presence of a crack alone does not prove that there is a serious foundation problem. The entire property needs to be considered.
2. Reactive Clay Soils
Soil conditions can play an important role in house movement.
Many areas throughout Melbourne have reactive clay soils that expand when they absorb moisture and shrink when they dry out.
During prolonged dry conditions, soil around foundations may shrink. Following substantial rainfall, moisture levels may increase and the soil may expand again.
Where these changes occur unevenly around the building, different sections of the foundations can move by different amounts.
Visible signs may include cracking around windows and doors, stepped cracking to external brickwork, internal plaster cracking, uneven floors and doors that no longer close correctly.
3. Problems With Steel Lintels
Not every crack above a window or door is caused by foundation movement.
Another important component to inspect is the lintel.
A lintel is installed above an opening to support the brickwork or other building materials above the window or door.
Steel lintels can deteriorate over time, particularly when exposed to moisture.
When steel corrodes, the resulting expansion can place pressure on surrounding masonry and contribute to cracking.
Signs of possible lintel deterioration may include cracking immediately above the opening, rust staining, deterioration of mortar or visible corrosion to exposed sections of steel.
Depending on the extent of deterioration, repairs or replacement may be required.
4. Stepped Cracking From Window and Door Corners
A staircase-shaped crack extending through the mortar joints from the corner of a window or door is generally referred to as stepped cracking.
This type of cracking deserves attention because it can be associated with movement occurring within the building.
The crack may extend diagonally upwards from the corner of the opening or follow the mortar joints through several courses of brickwork.
Small stepped cracks do not automatically mean that major structural repairs are required. However, substantial cracking, increasing crack widths or cracking accompanied by other evidence of movement should be investigated.
5. Cracking to Internal Plaster Around Openings
Cracking around windows and doors is not limited to external brickwork.
Internally, cracks may appear diagonally from the corners of door frames and window openings or at plasterboard joints.
Fine cracking may be associated with normal building movement or shrinkage of materials.
However, internal cracking becomes more significant when corresponding external cracks are present in approximately the same area.
For example, if stepped cracking is visible through external brickwork and diagonal cracking is also present internally, this may provide further evidence that movement has occurred through that section of the building.
6. Doors and Windows That No Longer Operate Correctly
Cracking should not be considered in isolation.
During an inspection, we also look at how the doors and windows are operating.
A door that suddenly begins binding against its frame, a window that becomes difficult to open or a noticeable change in the gap around a door may indicate movement or distortion.
Other warning signs can include separation between architraves and walls, cracking to plaster above door openings and uneven gaps around window frames.
When several of these symptoms occur together, further investigation may be warranted.
7. Could Poor Drainage Be Causing the Movement?
External drainage is another important consideration.
Blocked gutters, leaking downpipes, damaged stormwater drains, garden beds against walls and paving that directs water towards the house can alter moisture levels in the soil around the foundations.
Where reactive soils are present, significant differences in moisture conditions can contribute to uneven foundation movement.
During a building inspection, it is therefore important to examine not only the cracking but also the gutters, downpipes, ground levels, paving, drainage and surrounding site conditions.
The cause of a crack may sometimes be several metres away from where the crack itself appears.
Are Cracks Above Windows and Doors Structural?
Not necessarily.
Some cracks may be cosmetic or associated with relatively minor movement. Others can indicate more significant building movement or deterioration of structural components.
The seriousness of a crack cannot reliably be determined from its width alone.
An experienced inspector considers the location, direction, width, pattern and extent of the cracking, together with other evidence throughout the property.
The age and construction of the house, foundation type, soil conditions, drainage and whether movement appears to be ongoing are also important considerations.
When Should I Be Concerned?
Cracks around windows and doors deserve closer investigation when they are increasing in size or are accompanied by other signs of movement.
These signs may include:
- Significant diagonal cracking
- Stepped cracking through external brickwork
- Cracks that repeatedly reopen after repairs
- Doors that bind or no longer close properly
- Windows becoming difficult to operate
- Separation around window or door frames
- Uneven or sloping floors
- Corresponding cracking internally and externally
- Rust staining or deterioration around steel lintels
- Multiple cracks developing throughout the property
One isolated hairline crack may have little significance. Multiple related defects can tell a very different story.
Don’t Just Fill and Paint the Crack
One of the most common mistakes is repairing the visible crack without investigating why it developed.
Filling mortar joints or patching and repainting internal plaster may make the problem disappear temporarily.
However, if the underlying cause remains, the crack may return.
Where foundation movement, poor drainage or lintel deterioration is responsible, the cause should be identified before substantial cosmetic repairs are undertaken.
Cracks Around Windows and Doors When Buying a House
Cracking deserves particular attention during a pre-purchase building inspection.
Prospective purchasers should be cautious where cracking appears to have been recently patched, rendered or painted.
Recent cosmetic work does not necessarily mean the underlying cause has been rectified.
During a pre-purchase inspection, we look beyond the individual crack and assess other accessible areas of the property for visible signs that may indicate movement or deterioration.
This can include external brickwork, internal walls, ceilings, floors, doors, windows, lintels, drainage and surrounding ground conditions.
Professional Building Inspections in Melbourne
If you have discovered cracking above windows or doors in your existing home, or you are considering purchasing a property where cracking is visible, a professional building inspection can help provide a better understanding of the property’s condition.
We carry out building and pest inspections throughout Melbourne, assessing visible cracking together with other building and site conditions that may help identify the likely cause.
A crack above a window or door does not automatically mean that a house has a major structural problem. However, it should not automatically be dismissed as cosmetic either.
The important questions are:
What caused the crack? Is movement continuing? Is the lintel performing correctly? And is further investigation or repair required?
