Failed cavity wall ties are a structural risk, and a leading cause of horizontal cracking and bowing brickwork. We install stainless remedial ties through the existing wall, no demolition required.
What are cavity wall ties?
A cavity wall is two separate brick leaves with an air gap between them. The two leaves are tied together at regular intervals by metal wall ties, which transfer wind and lateral load from the outer leaf into the inner leaf. Without ties, the outer leaf is just a freestanding skin, and skins fall down.
On most Sydney homes built before about 1980, the original ties are twisted galvanised iron or sometimes mild steel. Their service life was always going to be limited by the galvanising, and many are now well past it.
Why ties fail
The same expansion problem that destroys lintels destroys wall ties. As the galvanising fails, the steel rusts; rust expansion forces the joints apart, lifting the courses around each tie and creating the characteristic horizontal cracking pattern. Eventually the tie corrodes through and the connection between the two leaves is gone.
The risk isn’t cosmetic. A cavity wall with no working ties has lost its structural redundancy, high winds or seismic loads can push the outer leaf out of plumb or, in extreme cases, off the wall entirely.
Signs of wall tie failure
Our installation process
Set out
Tie pattern set out per spec, typically 450mm vertical x 900mm horizontal centres, with closer spacing around openings and at corners. We mark every position before drilling.
Drill through
Small-diameter holes drilled through the outer leaf and into the inner leaf. The cavity is cleaned of debris.
Install the remedial tie
Stainless steel remedial tie installed, either helical, expanded-end mechanical, or resin-bonded depending on the substrate, engaging both leaves with full embedment.
Make good
Drill holes pointed up to match surrounding mortar. Where the work has been done through the joint, the result is invisible from outside.
For builders and engineers
We work to engineer-specified tie counts, embedment depths, and product selections. For each project we document tie positions on a marked-up elevation, take photos of every installation, and provide a completion report suitable for engineer sign-off, strata committee records, or insurance support.
Stainless ties are installed to AS 3700 and BS 8221 where applicable. We can supply manufacturer test data for any product specified.
FAQ
How many ties are needed?
For a standard residential cavity wall, AS 3700 specifies 2.5 ties per square metre, typically 450mm vertical x 900mm horizontal. Around openings and at corners the spacing tightens. For a 100m² elevation that’s around 250 ties. We calculate the exact count as part of every quote.
How do you know if ties have failed?
The crack pattern is usually conclusive, regular horizontal cracking at the tie spacing is wall tie failure until proven otherwise. Where it’s ambiguous, we can use a metal detector to locate existing ties and a borescope to inspect their condition through a small drilled hole. We do this as part of our diagnosis where the symptoms aren’t clear-cut.
Do you need to remove brickwork?
No. Remedial wall ties are designed to be installed through the existing wall, that’s the whole point of the technique. We drill small holes, install the tie, and point the holes up to match. From outside the work is invisible.
Get a detailed quote within 24 hours. Photos accepted via our Project Brief form.