Non-standard construction
Map cracking in the render of a Wimpey no-fines house follows no structural line. Why is that pattern not the same evidence as a horizontal tie-failure crack in a cavity wall?
Map cracking that follows no structural line is not the same evidence as a horizontal tie-failure crack. In this Wimpey no-fines house the cracks in the render wander, rather than tracking a tie line. No-fines concrete is not that cavity. The survey has recorded a render pattern. It has not tested the render or any ties. The pattern is map cracking, not a tie failure. The survey has not called this wall a cavity, and it has not found tie failure.
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?
A tie-failure crack in a cavity wall is a different building and a different mechanism: horizontal cracking linked to the ties that join two leaves. Map cracking is a net of fine cracks in a render coat, often from the coat itself shrinking or weathering, and here it follows no structural line. Wimpey no-fines is solid concrete. Treating the net as a tie failure sends the wrong investigation to the wrong wall. The survey did not sample the concrete and did not look for ties.
Keep the wording as map cracking in the render when you speak to a lender or a specialist in non-standard houses. Do not commission a wall-tie survey as if the pattern had already proved tie failure. Ask the surveyor to confirm the cracks follow no structural line. The home survey has not tested the concrete, and it should not be rewritten as a cavity-wall diagnosis.
What should you ask your surveyor?
- Does the map cracking follow no structural line?
- Why is that pattern different from a horizontal tie-failure crack?
- Did you leave the concrete and any ties untested?
What are the typical next steps?
- Describe map cracking in the render, not a tie failure.
- Do not commission a wall-tie survey on this pattern alone.
- Keep the no-fines wall distinct from a cavity wall.
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
If a crack is long, has it become a tie failure?
Not from length alone. The note is map cracking that follows no structural line. A long crack in render is still not the horizontal tie-failure pattern of a cavity wall. The survey has not tested ties. Length does not turn that pattern into a different wall.
Does hollow-sounding render prove the concrete has failed?
No. A hollow sound, if you notice one, is about the render coat parting. It is not a test of the no-fines concrete, and it is not evidence of cavity-wall tie failure. The survey left the concrete untested. Render sound is not a cavity diagnosis.