Wall ties and cavity insulation
Rust stains appear at regular brick courses on a coastal elevation. What mechanism is that pattern suggesting, and what has it not measured?
Because the stains sit at regular courses, the pattern suggests tie corrosion, and it has not measured the ties. Rust at a repeated brick course is what you can see when corroding ties sit on that spacing and stain the mortar or the face. Coastal exposure makes that suggestion easier to understand. It does not weigh the steel, count the ties, or say how much section is left. The survey can record the pattern and the elevation. It has not measured corrosion. Suggestion is not a caliper reading, and a regular stain is not a completed tie survey.
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?
Wall ties are built to a spacing, so staining that repeats with the courses is a clue that the marks are coming from those positions rather than from a random leak. The mechanism people are pointing at is expansive corrosion of the ties, bleeding rust to the face. Say that as a suggestion. Do not say the ties have been tested, drilled, or found to have failed a strength check. A home survey does not do that measurement by looking at stains.
The coast explains why you would take the pattern seriously. Salt air is a hard setting for embedded metal. It still does not tell you which ties are thin and which are not, or whether every elevation matches this one. Ask the surveyor which courses, which wall, and what they did not open. If you need the ties measured, that is a separate investigation with cores. Until then the report should say the pattern suggests corrosion and that the loss of metal was not measured.
What should you ask your surveyor?
- Which courses and which elevation carry the stains?
- Are you suggesting tie corrosion, or reporting a measurement?
- What would need opening before the ties themselves were known?
What are the typical next steps?
- Record the regular stains as a suggestion of tie corrosion.
- Do not state that the ties have been measured.
- Arrange a proper tie investigation if you need section and spacing known.
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
Do regular rust stains prove every tie has failed?
No. The pattern suggests corrosion at those courses. It has not measured the ties or shown that every tie has failed on this elevation.
Does a coastal site turn the stains into a test result?
No. The coast is context for the pattern. It does not measure the metal, and the survey has not done that either.