Wall ties and cavity insulation
What do horizontal cracks in regular brick courses suggest about wall ties?
Regular horizontal cracks, often every few courses, can suggest the outer leaf is being lifted or distressed by expanding rusty ties. They can also be ordinary movement, a render crack, or a joint that was cut for another reason. The pattern is a clue, not a verdict.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Rusty ties expand and crack the mortar bed they sit in. Surveyors look for that rhythm, for rust stains, and for whether the cracks are in the outer leaf only. A structural crack from foundation movement more often runs diagonally through bricks and openings. The two patterns are not the same repair.
Ask the surveyor which pattern they saw and whether they are recommending a tie inspection or a structural engineer. Those are different people. Replacing ties will not stop subsidence, and underpinning will not replace a rusted tie. Get the right next inspection. Its cost is that firm’s fee.
What should you ask your surveyor?
- Are the cracks in the mortar beds only, or through the bricks as well?
- Do they line up in a regular rhythm, or do they step diagonally?
- Which specialist do you mean: a tie inspector or a structural engineer?
What are the typical next steps?
- Photograph the pattern with a scale before anyone rakes the joints out.
- Do not repoint as the first job if the ties are expanding. The cracks can return.
- Commission the inspection the surveyor actually named, and ask them to confirm if you are unsure which one.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Can bed-joint reinforcement be the cause of those lines?
A repaired wall may already have been cut and stitched. Ask the seller for paperwork. New mortar in regular lines can be a previous tie job, not a new failure.
Does cavity insulation cause this cracking?
Insulation does not expand like rusty steel. It can hide ties and it can hold moisture. The crack pattern still has to be explained by someone who can see the metal.