Wall ties and cavity insulation
A render coat may be hiding horizontal cracks in the brick. What can a visual survey not claim about the ties under that coat?
Not the ties under the render. A visual survey cannot claim what the ties are doing beneath a coat that may be hiding horizontal cracks in the brick. Horizontal cracks in courses can be a sign associated with corroding ties, but only if the brick is seen. Render covers that evidence. The survey can describe the render. It cannot say the ties under it are sound, and it cannot say they have failed, unless some other opening actually showed them. Hidden brick is hidden ties. Do not let a smooth coat become a tie report.
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?
People connect horizontal cracking with tie corrosion because expanding rust can lift courses in a line. That link needs the brick, or an opening, before anyone uses it. A render coat may conceal those cracks, which means the surveyor may have no crack to record and no tie to see. The honest sentence is that the coat stopped the look. It is not a sentence that the ties are fine because no crack was visible in the render.
If render has cracked in a horizontal line, describe the render crack as a render crack. Do not automatically rename it as tie failure. The Energy Saving Trust's cavity-fill advice does not see through render either. A more detailed survey still cannot claim the metal it has not exposed. If you need the ties known, agree an opening. Until then the visual survey's limit is the limit. What it cannot claim is the condition of the ties under that coat.
What should you ask your surveyor?
- What of the brickwork, if any, was visible through or beside the render?
- Are you describing render, or claiming a pattern of cracks you could not see?
- What opening would be needed before the ties could be discussed as seen?
What are the typical next steps?
- State that render may hide horizontal cracks in the brick.
- Do not claim the ties under the coat are sound or failed.
- Agree an opening if the ties themselves need to be 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
Can a smooth render coat clear the ties?
No. A visual survey cannot claim the ties under render that may be hiding the brick courses or the cracks under the coat.
If the render is cracked horizontally, have the ties failed?
Not from the coat alone. A crack in render is not a measurement of the ties beneath it and should not be treated as one.