What We Fix
Plaster & Internal Wall Damage
Find out why your plaster keeps cracking — and how to fix the wall behind it so the surface fix lasts.
- Free assessment · 1–2 day repair · 20-year warranty
- Structural Engineers · Licensed Builders · Skilled Technicians
Trustpilot
GoogleWhat We Fix
Plaster & Internal Wall Damage
Find out why your plaster keeps cracking — and how to fix the wall behind it so the surface fix lasts.
- Free quote · 1–2 day repair · 20-year warranty
- Structural Engineers · Licensed Builders · Skilled Technicians
Plaster & Internal Wall Damage
Find out why your plaster keeps cracking — and how to fix the wall behind it so the surface fix lasts.
- Free structural assessment with a fixed-price quote
- Structure reinforced — then skimmed and paint-ready
- 20-year product and workmanship warranty
Structural Engineers · Licensed Builders · Skilled Technicians
TrustpilotGoogleWhy does my plaster keep cracking?
Plaster cracks happen in every home eventually. A hairline crack above a door frame, a fine line where the wall meets the ceiling — most of the time, a bit of filler and a coat of paint sorts it out. No drama.
But when the cracks keep coming back — same spot, sometimes wider — filler isn't fixing anything. It's hiding it. The plaster isn't the problem. The wall behind it is. Foundation movement, structural cracks in the brickwork, rising damp eating away at the masonry — these are the forces that push through plaster. Until the cause is addressed, every repair is temporary.
The signs below will help you work out whether your plaster damage is cosmetic or structural — and what to do about it.
What are the symptoms of plaster & internal wall damage?
Not all plaster damage is cosmetic. Here are the interior signs that point to something deeper.
Cracks Above Door Frames
A crack that starts at the corner of a door frame and runs diagonally toward the ceiling. The door frame is rigid — when the wall around it moves, the stress concentrates at the corners and the plaster splits. If the door is also sticking or the frame is visibly out of square, the foundation beneath that section of wall has likely shifted.
Cracks That Run Floor to Ceiling
A single crack that travels the full height of the wall — from near the skirting to the cornice. This isn’t surface movement. A crack that long means the masonry behind the plaster has separated into two sections that are moving independently. The wall has stopped working as one piece. Filler won’t hold it — the structure needs reconnecting.
Cracks Near Corners
A crack that follows the corner where two walls meet, running vertically from partway up the wall into the ceiling. Corners are where two sections of masonry join — and when the foundation moves unevenly, this joint is the first to give. If the cornice above is also separating, the movement is pulling the walls apart.
Cracks That Close During Rain
A crack that seems to close up after heavy rain, then opens again in dry weather. This is reactive clay at work — the soil beneath your home swells when wet and shrinks when dry, and the foundation moves with it. The crack isn’t healing. It’s breathing with the seasons. If your home is on clay across Western Sydney, Melbourne’s west, or South East Queensland, this pattern is common.
Cracks That Join with Cornice Gaps
A gap opens between the cornice and the wall — and a crack in the plaster below runs up to meet it. The two aren’t separate problems. The wall has dropped or tilted away from the ceiling, pulling the cornice joint apart and cracking the plaster on the way. If the gap is wider on one side of the room than the other, the movement is uneven — and structural.
Cracks That Spread Across the Wall
What started as a single crack has branched into a web — spreading up, down, and sideways across the wall. This happens when the structure behind the plaster has moved enough that stress is no longer concentrated in one place. The wall is redistributing load through the only path it has left: the cracks. Multiple spreading cracks on the same wall are a clear sign the movement is ongoing.
What does structural plaster damage look like?
How to fix plaster wall damage permanently
Reinforced. Replastered. Guaranteed.
Fix the Structure. Then Fix the Surface.
The fix depends on what's causing the damage. That's why every plaster wall repair starts with a free structural assessment — a structural engineer identifies whether the problem is foundation movement, cracked brickwork, or rising damp before anything is touched. No replastering over the top and hoping for the best.
If the damage is driven by structural wall cracks, HelicalBar™ R304 stainless steel reinforcement bars are bonded into the mortar joints behind the plaster — spanning the crack and locking both sides of the wall back together. The bars sit concealed inside the masonry, invisible from either side, and around 100 times tougher than the bricks themselves. Once the wall is structurally reconnected, the surface is finished with gypsum plaster and left paint-ready.
If the foundation has moved, GeoPoly™ resin injection stabilises and relevels the ground first. If rising damp is the cause, DampBlock™ installs a new damp proof course to stop the moisture at its source. The plaster is only finished once the structural issue is resolved.
Not sure what's behind your plaster damage? That's exactly what the free assessment answers.
What to expect
A step-by-step guide of how the plaster wall damage repair process works — from assessment to completion.
Step 1Free Structural Assessment
A Buildfix engineer inspects your home, examines the plaster damage, and looks behind it — checking for foundation movement, structural cracks in the brickwork, and signs of rising damp. The cause is identified on-site and the repair plan 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 3HelicalBar™ Installation
Technicians cut precise slots through the plaster and into the mortar joints behind, then bond stainless-steel HelicalBars™ with high-strength structural grout. This reconnects the cracked structure at depth, tying separated sections of wall back together so they work as one piece again.
Step 4Replaster and Finish
Once the HelicalBars™ are locked in, the plasterwork is repaired over the top. Cracks are filled, surfaces are skimmed smooth, and the wall is left paint-ready. For heritage homes, gypsum plaster is used rather than rigid cement render — sympathetic to the original character. When the team packs up, you’d hardly know they were there.
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™ plaster wall repairs — before and after.
Structural fix.
Guaranteed to last.
The benefits of fixing plaster and internal wall damage with HelicalBar™.
Internal wall damage usually starts behind the plaster. HelicalBar™ bars are bonded into the centre of the brickwork through neat channels — reinforcing the wall permanently, not just patching the surface. Loads spread evenly again, 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 plaster wall 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.
