Cavity Wall Tie Failure
The hidden steel ties holding two brick walls together rust and fail — most 1960s-80s brick veneer homes are affected.
Cavity wall ties are steel ties embedded in the mortar between the two leaves of a cavity brick wall, holding them together. In 1960s–80s Australian brick veneer homes they often corrode as the galvanising fails, and once they corrode they stop doing their job. Signs include horizontal cracks at regular spacing, bowing walls, and cracked mortar in horizontal joints. The fix is installing new stainless steel remedial wall ties — a proven, non-destructive repair. Romans Building Services assesses cavity wall tie failure across Sydney before recommending repair, so the visible damage and the cause are both dealt with.
Last updated: 2026-05-29
What is cavity wall tie failure?
Cavity wall construction has two leaves of brick with a small gap (cavity) between them, tied together by steel ties embedded in the mortar joints. The ties stop the two leaves from separating. They were standard construction for Australian brick veneer homes from the 1940s through to around 1990.
The problem: the ties were galvanised mild steel, and the galvanising fails over decades. Once the galvanising is gone, the steel rusts — and once it rusts significantly, it stops doing its job. The two leaves of the wall are no longer held together properly. Over years, the outer leaf can start to bow outward, and the mortar joints where the ties sit crack horizontally at regular intervals.
This is a widespread issue on Sydney homes built from 1950 to 1985. Most homes of that vintage will have some tie corrosion, and many have significant enough corrosion to need remedial wall ties installed. The fix is non-destructive — new stainless steel ties are installed through small holes drilled from outside, then the holes are repointed.
Signs to look for
- Horizontal cracks in mortar joints at regular spacing (roughly 450–600mm apart)
- Outer brick leaf bowing or leaning outward
- Stair-step cracks radiating from window or door corners
- Bricks loose or moving in sections of the wall
- Rust stains at mortar joints (rare — usually hidden inside)
- Visible gap between internal and external walls at junctions
- Home was built between 1950 and 1985 (age bracket for affected construction)
Why it happens
- Original galvanising wearing out over 30+ years
- Moisture ingress through cracks, damp or failed flashing
- Salt air (coastal homes) accelerating corrosion
- Poor original construction — inadequate tie spacing or wrong tie type
- Thermal expansion over decades flexing the ties and breaking galvanising
How urgent is this?
Cavity wall tie failure is rarely an emergency — it progresses slowly over years. But once the outer leaf starts bowing noticeably, the repair scope gets bigger and the risk of more serious structural failure grows. Homes in coastal suburbs or with visible tie corrosion warrant action sooner. For homes showing just hairline horizontal cracking, monitoring for change is reasonable.
How we fix it properly
Diagnose the failure pattern
We check the spacing of horizontal cracks, look for bowing with a straight edge, and sometimes open up a small section of mortar to inspect tie condition. Confirms whether the problem is tie failure or something else.
Calculate new tie layout
New remedial ties are specified in a grid pattern across the affected walls — typically 450mm vertical spacing and 600–900mm horizontal. More ties near corners and openings where stress concentrates.
Drill and install new ties
Small holes (10mm diameter) drilled through the outer leaf into the inner leaf, at the specified locations. Stainless steel helical remedial ties driven in to lock both leaves together. The ties bite into the masonry on both sides and do not need resin or mechanical fixings.
Seal and repoint
Tie heads are set back below the brick face and the small drill holes are repointed with matched mortar. Done carefully, the repair is practically invisible.
Monitor movement
For homes where the outer leaf had already bowed, we install monitors and review after 12 months to confirm movement has stopped.
Typical cost range
Per tie: $45 – $90 installed. A typical home needs 100–300 ties. Total jobs usually $8,000 – $25,000 depending on home size, wall condition and access.
Every job is different. We give a firm quote after inspection.
Common questions
How do I know my cavity wall ties have failed?
Horizontal cracks in mortar joints at regular spacing (450–600mm) are the classic sign. Bowing of the outer leaf when checked with a straight edge is another. Your home also has to be from the right era — 1950s to 1980s brick veneer — to have this specific problem.
Is cavity wall tie failure dangerous?
Eventually, yes — if the outer leaf fully separates it can collapse. In practice this happens over decades of untreated decay. The reasonable approach is to fix the ties when signs appear rather than wait for catastrophic failure.
Will the new ties last?
Stainless steel remedial ties have effectively unlimited service life in Australian conditions. 50+ year warranties are standard. They will not rust and will not need replacement during the useful life of the building.
Will the repair damage my interior walls?
No — the repair is entirely external. Drilling is from outside only, so there is no interior work, no need to move furniture, and no internal disruption.
Where we see cavity wall tie failure most often
Some suburbs have more of this problem than others — the local housing stock, age, and coastal exposure all play a part. Click through for the local context.
Think you might have cavity wall tie failure?
Send a photo or call Minas directly. We will tell you straight whether it needs doing now, or whether it can wait.