What We Fix
Wall Cracks
Find out what your wall cracks mean — and how to fix them permanently without knocking the wall down.
- Free assessment · 1–2 day repair · 20-year warranty
- Structural Engineers · Licensed Builders · Skilled Technicians
Trustpilot
GoogleWhat We Fix
Wall Cracks
Find out what your wall cracks mean — and how to fix them permanently without knocking the wall down.
- Free quote · 1–2 day repair · 20-year warranty
- Structural Engineers · Licensed Builders · Skilled Technicians
Wall Cracks
Find out what your wall cracks mean — and how to fix them permanently without knocking the wall down.
- Free structural assessment with a fixed-price quote
- No walls knocked down — most repairs done in 1–2 days
- 20-year product and workmanship warranty
Structural Engineers · Licensed Builders · Skilled Technicians
TrustpilotGoogleDo wall cracks mean my home has a structural problem?
Wall cracks happen. Over time, every home develops a few. Some are surface-level — a bit of paint and filler sorts them out. Others run deeper.
The difference matters. A cosmetic crack is a nuisance. A structural crack is your home telling you something has changed — the ground has moved, bricks have expanded, or the wall has lost the ties holding it together. Knowing which one you're looking at changes everything about what to do next.
The symptoms below will help you work out what your wall cracks are telling you — and whether a structural engineer should take a look.
What are the symptoms of wall cracks?
Not all wall cracks are the same. Here are the patterns that point to something deeper.
Stepped Cracks
A crack that follows the mortar joints in a staircase pattern — up one bed joint, across the next. Bricks are rigid; they don’t bend. When the ground shifts, the wall gives way along its weakest line: the mortar. Slide a credit card into the crack. If it fits and wiggles freely, the crack is wider than 5 mm and the foundation beneath that section of wall has almost certainly moved.
Cracks You Can See Through
If daylight comes through a wall crack, the wall has separated — it’s no longer a single structural unit. The two sides are moving independently. Hold a torch on one side and check for light on the other. If you can see it, the crack isn’t the problem. The crack is the messenger.
Cracks Near Corners and Downpipes
Cracks that appear near corners, downpipes, or subfloor vents. Water from a leaking or unconnected downpipe saturates the soil in one spot, and the foundation drops locally. The crack follows the mortar joints right next to the source of the problem. Check your downpipes — if one isn’t connected, that’s likely where the movement started.
Corner Cracks
Clay bricks expand over time — sometimes several millimetres per year. Over decades, that expansion builds a lateral force that drives walls into each other at the corners. The cracks that appear are vertical and tight. Run your finger along the joint — if the mortar has crumbled and the bricks feel like they’re pushing apart, expansion is the cause.
Internal Corner Cracks
A vertical crack running down the corner of an interior wall — from ceiling to floor. This usually means the external wall is moving independently from the internal wall. The plaster cracks where the two walls meet. If the crack is wider at the top, the wall is rotating outward.
Recurring Cracks
The crack you filled last year is back. Same spot, sometimes wider. Recurring cracks are the single most reliable indicator that the cause hasn’t been fixed — whether that’s the foundation, brick expansion, or failed ties. Press on the filler — if it’s loose or has pulled away from the edges, the wall is still moving beneath it. That’s the plasterer’s trap: fill, paint, repeat.
What do structural wall cracks look like?
What causes wall cracks?
Wall cracks are the symptom. The cause could be underground, inside the cavity, or in the bricks themselves.
Reactive Clay Soil
Reactive clay is the single biggest cause of structural wall cracks across Melbourne, Western Sydney, and South East Queensland. The soil swells when wet, shrinks when dry, and moves your foundation with it. The wall above has no choice but to crack.
Additional Loads
Renovations, extensions, second-storey additions — every extra load pushes more force onto the foundation and the soil beneath it. If that force isn’t evenly distributed, the ground gives way at the weakest point. Wall cracks are the first sign the balance has shifted.
Poor Drainage
Unconnected pipes, broken drains, overflowing gutters — any of these lets water collect in the soil beneath your home. Over time, the water erodes the ground, creates voids, and the foundation sinks into them. The walls crack as the structure follows.
Poor Workmanship
Shortcuts during construction eventually surface as wall cracks. Uncompacted fill, missing drainage, skipped soil testing — the foundation was never going to stay stable. The cracks are the house catching up with corners that were cut decades ago.
Expanding Materials
Clay bricks expand over their lifespan. Concrete can shrink and deflect. Both create stress on the structure. If expansion joints are missing or undersized, the wall has nowhere to go — so it cracks.
Poor Design
Building codes have changed significantly over the decades. A home that met standards when it was built may not handle the forces expected today — heavier roofs, different soil classifications, changed drainage patterns. The design wasn’t wrong at the time. The conditions changed.
What causes wall cracks?
How to fix wall cracks
Non-Invasive. Permanent. Guaranteed.
Keep Existing. No Walls Knocked Down—Ever.
Your home's walls are designed to work as a single unit — distributing the weight of everything above them evenly down to the footing. When a structural crack opens, that unit breaks. The sections either side of the crack start working independently. Loads shift. Stress concentrates. The wall can't do what it was built to do.
Reinforcing it reconnects those sections — and that's exactly what HelicalBar™ R304 does. High-tensile stainless steel masonry reinforcement bars, around 100 times tougher than the bricks themselves, are bonded into the mortar joints. The bars extend across the full wall, redistributing load evenly and returning your home back to what it was originally designed to do. What was the weakest point in your home becomes the strongest.
Not sure what your cracks need? That's exactly what the free assessment answers.
What to expect
A step-by-step guide of how the wall crack repair process works — from assessment to completion.
Step 1Free Structural Assessment
A Buildfix engineer inspects your home, measures the cracks, identifies the root cause, and designs a repair plan on-site. Measurements, photos, and markings are recorded using mobile software — and the price is usually explained there and then.
Step 2Get Your Quote and Book
A complete quote package arrives — detailed drawings, repair method statement, and a fixed-price quote. The price you see is the price you pay. When you’re ready, book through the online portal and suitable dates are organised for the work.
Step 3Fixing Your Wall Cracks
Technicians mark out the wall, cut neat slots into the mortar joints, and bond HelicalBar™ stainless steel bars into the brickwork with high-strength structural grout. The wall is structurally reconnected right where it’s needed most.
Step 4Final Touches and Clean-Up
Mortar is repointed, cracks filled, and brickwork colour-matched — or render and plaster blended for a smooth, uniform finish. The site is cleaned and your home left looking exactly as it did before. Except now the wall is stronger.
Step 5Receive Your Warranty
Your 20-year product and workmanship warranty arrives via email with the Completion Package — a job report covering the work, materials, and images.
See the difference
Actual HelicalBar™ wall crack repairs — before and after.
Structural fix.
Guaranteed to last.
The benefits of fixing wall cracks with HelicalBar™.
Wall cracks mean the masonry has separated — it can’t carry loads as one piece. HelicalBar™ stainless steel bars are bonded into the mortar joints, reconnecting both sides of the crack. The wall works in a uniform manner again — loads spread evenly and distributed through the foundations as designed.
Not sure if it's subsidence? Get your home assessed for free — we'll explain exactly what's going on and what can be done.
Real homes. Real results.
15,000+ homes and structures repaired. Want to see real Buildfix wall crack repairs? Browse a few below.
HomeownerStrathfield, NSW
Heritage Home Repaired Twice, Same Team
When new cracks appeared in this 150-year-old Strathfield home, the owner didn’t hesitate — they called Buildfix again. Buildfix had already fixed the front of the house years earlier. This time, the team tackled the rear.
HomeownerRandwick, NSW
Hidden Downpipe Behind 10 Years of Cracks
A neighbour’s redirected downpipe quietly washed out the soil beneath this Randwick home for over a decade. Buildfix found the cause, stabilised the ground, and reconnected the cracked walls — no demolition required.
HomeownerWindsor, VIC
Wall Cracks Traced to a Hidden Void
Every expert said “seasonal movement.” But the cracks kept spreading — including right above a child’s bed. Buildfix found the real cause: years of driveway runoff had quietly washed out the ground beneath the walls.
CommercialAshfield, NSW
Heritage Fairground Wall Rescued
An 80-year-old heritage brick wall at a fairground and cricket ground, damaged by decades of impacts and tree root shifts. Buildfix replaced corroded steel, reinforced the cracks, and stabilised the ground — saving the council over $30,000.
HomeownerSt Kilda, VIC
Bungalow Repaired After 2021 Earthquake
After the 2021 Melbourne earthquake left an 80-year-old California Bungalow with cracked arches and shifting foundations, Buildfix repaired the damage in just three days — without removing a single brick.
“All of the Buildfix team have been easy to communicate with. Everyone was punctual and communicated arrival times well ahead of arrival.”
Scott HolmesMelbourne, VIC
“All of the Buildfix team have been easy to communicate with. Everyone was punctual and communicated arrival times well ahead of arrival.”
Scott HolmesMelbourne, VIC
“All of the Buildfix team have been easy to communicate with. Everyone was punctual and communicated arrival times well ahead of arrival.”
Scott HolmesMelbourne, VIC
“All of the Buildfix team have been easy to communicate with. Everyone was punctual and communicated arrival times well ahead of arrival.”
Scott HolmesMelbourne, VIC
Questions?
Our team is here to answer any questions you may have Monday – Friday 8am to 4pm AEST. Give us a call on 1300 854 115.
