Wall tie failure is when the ties rust and expand, forcing the brickwork apart. Common in cavity walls built between 1920 and 1980. What a failed tie looks like, how to spot one from outside, and what fixing it involves.
The brief
Last reviewed · 13 August 2026
Most cavity-wall homes in the UK built before the mid-1980s have wall ties of a generation that were prone to corrosion. As ties corrode they expand, lifting the outer leaf of brickwork off the inner leaf, and producing the characteristic horizontal crack patterns. Diagnosis is easy. Fix is moderate. Ignoring it is expensive.
When a wall tie rusts and expands, the brickwork moves and the mortar no longer adheres to the brick. This results in the wall becoming unstable.
The photograph shows old style wall ties that have been badly corroded. This happens when rainwater seeps through gaps in the pointing, reaches the tie, and the rust that forms takes up more room than the steel it replaced. That expansion is what lifts the courses apart.
Corroded wall ties can devastate a property. In the most severe cases, as with this terraced house in Fenton, Stoke-on-Trent, part of the house is having to be rebuilt.
As John explains in the video, cracks in brickwork can sometimes be repaired using brick stitching. However, in this case, the wall was in such a poor state that it had to instead be rebuilt.
In the first film of the pair, John explains how you can spot a wall where the brick ties have failed.
Look out for horizontal cracks in the mortar. They follow the bed joints, which is what makes them different from settlement cracks, and they tend to repeat at regular heights up the wall, because that is where the ties sit.
From outside, the other thing to look at is the line of the courses, particularly where your property meets next door. Where ties have expanded, the brickwork lifts, and the rows on one side stop matching the rows on the other.
0:44 · John shows us the rear wall of the property, which has been partly removed because of the consequences of wall tie failure.
3:13 · When pointing perishes on the outer wall, rainwater seeps into the wall. Wall ties get wet, begin to rust and start to expand.
3:38 · The pointing on this particular property had perished to the point that it was possible to see daylight through the brickwork.
3:56 · Helifix brick stitching can be used for repairing structural failure in brickwork. But this wall was too badly damaged for this method.
4:28 · Modern wall ties (brick ties) are made from stainless steel and, therefore, far less susceptible to rust.
5:51 · The rear wall of the property is so badly damaged due to the corroded wall ties that the brickwork has started to bow under pressure.
I was in the process of purchasing an investment property. There were several structural issues with the property including wall tie failure. I required an experienced person to advise on the best solution to move forward. John was able to advise not only from a structural/building point of view but also from an investment perspective.
On a terrace this question comes up immediately, and it matters because it changes who pays.
The ties are in your wall. Where the party wall is involved, or where the movement has carried across into the adjoining property, it stops being a job you can simply get on with and becomes a conversation with next door and, usually, a structural engineer.
John walks the outside of the Fenton property and its neighbour in the first film, which is the quickest way to see what a whole elevation looks like when the ties have gone.
A structural engineer will be able to determine which method is needed to properly repair a wall with failed wall ties.
Sometimes remedial works such as brick stitching are possible. In more serious cases, the wall may have to be rebuilt.
Where the wall can be saved, the failed ties are cut out or isolated and replacement ties are installed. Modern wall ties are stainless steel, so the same thing does not happen again in another fifty years.
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John walks the Fenton property where the ties had gone far enough to take the rear wall down, and shows what came out of the cavity. Every photograph on this page is a frame from this film or its first part.
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