The good news is that not every cracked brick wall means your home has a serious structural problem. Some brick wall cracks are minor and may relate to normal building movement, weather exposure, thermal expansion or ageing mortar. Others may be signs of foundation movement, reactive clay soil movement, subsidence, voids or foundation settlement.

So, what should you do first?

Start by checking the size, shape, location and pattern of the cracks. Then look for other signs of movement around the home, such as sticking doors, uneven floors, gaps around windows or cracks appearing inside as well as outside.

If the cracks are widening, running diagonally or in a stair-step pattern, or appearing with other signs of movement, it may be time to arrange an expert site assessment.

Mainmark has provided ground engineering, foundation repair and house re-levelling solutions since 1989, helping Australian homeowners identify and address issues caused by ground movement, weak soils, voids and foundation settlement.

If you have noticed cracks in brickwork, do not panic and do not rush straight to cosmetic patching.

Instead, follow this simple first-step action plan.

1. Take clear photos of the cracks

Photograph each crack from a distance and up close. Include a ruler, coin or tape measure in the photo so you can compare changes over time.

2. Record the date

Write down when you first noticed the cracks in brick walls. If you are unsure, note when you first became aware of them.

3. Measure the width

Very fine cracks may only be hairline cracks in the mortar or brickwork. Wider cracks, cracks that are increasing, or cracks that open and close with seasonal weather changes may need closer attention.

4. Check the crack pattern

Look at whether the crack is vertical, horizontal, diagonal or stair-step. The pattern can help indicate whether the cracking may be cosmetic, moisture-related or linked to foundation movement.

5. Look for other warning signs

Check whether doors or windows are sticking, floors feel uneven, gaps have opened around skirting boards, or internal wall cracks have appeared nearby.

6. Monitor or arrange an assessment

If the cracks are small, unchanged and isolated, monitoring may be appropriate. If they are widening, spreading or linked to other movement signs, arrange an expert assessment before repairing the brickwork.

Learn more about when to worry about cracks

No. Cracks in brick walls are not always serious.

Some cracks in exterior brick walls may be caused by normal movement, minor settlement, changes in temperature, ageing mortar, or localised brickwork issues. These may be mainly cosmetic, especially if they are fine, isolated and not changing.

However, some house brick cracks can point to a deeper issue. When cracks are wide, growing, repeated across the home or appearing with other symptoms, they may indicate movement in the foundations or ground supporting the home.

The key question is not only “Is there a crack?” but “Why has the crack appeared, and is it changing?”

Different crack patterns can suggest different causes. While a visual check cannot replace a professional assessment, understanding the crack type can help you decide what to do next.

Stair-Step Cracks in Brick Walls

Stair-step cracks in brick walls often follow the mortar joints in a stepped pattern. They may appear around corners, near windows and doors, or across external walls.

These cracks can be a warning sign of differential movement, where one part of the home moves differently to another. This may happen when the ground beneath part of the home settles, shrinks, softens or loses support.

If stair-step cracks are widening or appear with sticking doors, uneven floors or internal cracking, it is worth arranging a site assessment.

Vertical Cracks in Brick Walls

Vertical cracks in brick walls may appear in the mortar, through individual bricks, or near joints between different parts of the home.

Some vertical cracking can be related to normal expansion and contraction, especially where movement joints are missing or not performing as intended. However, vertical cracks can also occur when part of the structure has moved or when there is stress around openings.

If a vertical crack is narrow and unchanged, it may be suitable to monitor. If it is widening, long, repeated or accompanied by other movement signs, it should be assessed.

Horizontal Cracks in Brick Walls

Horizontal cracks in brick walls can be more concerning, particularly if the wall appears to be bowing, leaning or separating.

Horizontal cracking may relate to lateral pressure, movement in retaining elements, corrosion of embedded components, or structural stress. It should not be ignored, especially if the crack is wide or the wall surface is distorted.

If you notice horizontal cracking in exterior brick walls, arrange professional advice before attempting repairs.

Diagonal Cracks in Brick Walls

Diagonal cracks in brick walls are often seen near windows, doors, corners or changes in wall height.

These cracks may suggest that part of the home has moved unevenly. In Australian homes, this can sometimes be linked to reactive clay soils, moisture changes, poor drainage, tree root activity, erosion, voids or foundation settlement.

Diagonal cracks that widen over time or continue through internal walls may be signs of foundation movement.

Cracks Around Windows and Doors

Cracks around windows and doors are common because these areas are natural stress points in a home.

A small crack near the corner of a window may not be urgent. However, if the crack is diagonal, growing, or appears with windows and doors that stick, jam or no longer close properly, the issue may be more than cosmetic.

Ask yourself: has the crack appeared because the brickwork has aged, or because the opening has moved out of alignment?

Learn more about types of cracks

Australian homes are exposed to a wide range of soil, weather and construction conditions. Brick veneer homes, double brick homes and older masonry homes can all show cracking for different reasons.

Reactive Clay Soils

Reactive clay soils are common in many parts of Australia. These soils expand when they absorb moisture and shrink when they dry out. Over time, this movement can place stress on footings, slabs and brickwork.

Long dry periods, heavy rain, leaking pipes or inconsistent moisture around the home can all contribute to movement. Learn more about foundation types 

Changing Moisture Conditions

Moisture variation is one of the most common contributors to house movement. Poor drainage, blocked gutters, leaking stormwater pipes, garden beds against the house, or water pooling near footings can affect the ground supporting the home.

When one area of ground becomes wetter or drier than another, parts of the home may move differently.

Foundation Settlement

Foundation settlement occurs when the ground beneath part of the home compresses, shifts or loses support. This can lead to cracks in brick walls, cracks in internal walls, uneven floors and gaps around openings.

Settlement may be related to weak soil, poor compaction, erosion, voids or changes in ground conditions over time.

Tree Roots and Vegetation

Large trees close to a home can influence soil moisture. In reactive clay areas, tree roots may draw moisture from the soil, contributing to shrinkage and movement.

This does not mean every nearby tree is a problem, but vegetation and moisture management should be considered when assessing cracks in brickwork.

Renovations, Extensions and Added Loads

Cracks can also appear where extensions, garages, patios or renovated sections meet the original home. Different footing systems, different construction ages or added loads may cause movement between sections.

If cracks appear near an extension joint or new renovation, it is worth checking whether the movement is localised or part of a broader issue.

Cracks in brick walls should be taken more seriously if they appear with other signs of foundation movement.

Look for:

• Stair-step cracks in brick walls
• Diagonal cracks running from windows or doors
• Cracks that are widening over time
• Multiple cracks appearing across different walls
• Cracks visible inside and outside the home
• Doors or windows sticking, jamming or not latching
• Uneven, sloping or bouncy floors
• Gaps between walls, ceilings, floors or skirting boards
• Cracks in concrete paths, driveways or patios near the home
• Evidence of water pooling, erosion or poor drainage around the property

One sign on its own may not confirm a foundation issue. Several signs appearing together are a stronger reason to arrange an expert assessment.

You may be able to monitor brick wall cracks if they are:

• Very fine
• Isolated to one small area
• Not changing over time
• Not connected to doors, windows or corners
• Not appearing with internal cracks or uneven floors

Monitoring should include photos, measurements and dates. Check the crack again after heavy rain, dry periods and seasonal changes.

You should arrange an expert assessment if the cracks are:

• Wider than hairline cracks
• Growing or spreading
• Stair-step, diagonal or repeated
• Appearing around windows and doors
• Present on both internal and external walls
• Linked to sticking doors, uneven floors or visible settlement
• Close to areas with poor drainage, leaking pipes or erosion
• Concerning during a property sale, purchase or renovation

If you are buying, selling, renovating or planning major work, it is better to understand the cause before investing in cosmetic repairs.

It can be tempting to fill cracks, repoint mortar or repaint the affected area straight away. While cosmetic brick wall crack repair may improve appearance, it may not address the underlying cause.

If the crack is caused by foundation movement, weak ground, voids or settlement, the cracking may return after patching.

Before repairing the visible brickwork, it is important to understand whether the wall itself is the issue or whether the ground supporting the home has moved.

Mainmark helps homeowners assess whether cracks in brickwork may be linked to ground movement, subsidence, weak or reactive soils, voids or foundation settlement. Where suitable, Mainmark may recommend ground improvement, resin injection, void filling, slab lifting, house re-levelling or other structural support solutions.

Mainmark provides foundation repair and house re-levelling solutions for Australian homeowners dealing with cracked walls, sinking floors, uneven slabs and other signs of ground movement.

Rather than starting with disruptive excavation, Mainmark assesses the site conditions and the likely cause of movement. Depending on the property, Mainmark may be able to use non-invasive resin injection technology to improve ground support, fill voids and help re-level affected areas.

This approach may reduce the need for traditional underpinning or major excavation, depending on the condition of the home, the soil and the extent of movement.

Mainmark’s experience since 1989 means homeowners receive practical advice based on decades of ground engineering and foundation repair work across Australian homes, commercial properties and infrastructure assets. Learn more about Mainmark

A site assessment helps identify what may be causing the cracks and whether the issue is likely to be cosmetic, localised or related to ground movement.

During the assessment process, the team may consider:

• The location, width and pattern of brick wall cracks
• Whether cracks are changing over time
• Internal cracking or floor movement
• Drainage, moisture and site conditions
• Soil behaviour and surrounding ground
• Signs of voids, settlement or subsidence
• The age, construction type and layout of the home
• Whether resin injection, house re-levelling or another solution may be suitable

The goal is to understand the cause before recommending a repair method.

Mainmark can help assess whether your brick wall cracks are cosmetic or may be linked to ground movement, subsidence, weak soils, voids or foundation settlement.

Contact Mainmark to arrange a site assessment and get practical advice on the right next step for your home.