Non-standard construction
The report mentions a china-clay stain next to a granite lintel. Has concrete block the stain does not classify been tested, or only named?
Only named. A china-clay stain next to a granite lintel does not classify the concrete block beside it, and that block has not been tested. The stain is a surface mark. The lintel is a stone beam over an opening, a different material from the block. RICS guidance on the mundic problem is for surveyors in the south west. Cornwall Council describes a core test and does not provide it. A home survey does not drill cores or award Class A, B or C. The report named the stain and the lintel. It has not classed the block.
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?
China-clay staining can sit on masonry for reasons that have nothing to do with a laboratory class: damp, old mortar, or dust from the stone. A granite lintel is not the concrete block that carries the mundic question. Colour beside the lintel does not identify the aggregate in the block, and this visit did not sample that block. RICS writes the mundic guidance for surveyors in the south west. The council guide describes a core test the council does not itself provide. Naming a stain has left the block unclassified.
Tell the solicitor the stain and the granite lintel were noted and that no class was awarded for the concrete block. If a core test is to be considered, that is a separate instruction to a firm that does that work. Cornwall Council describes such a test and does not provide it. Do not brief a lender that the walls have a class. The home survey has not drilled cores and has not awarded Class A, B or C.
What should you ask your surveyor?
- Was the china-clay stain only a surface mark beside the granite lintel?
- Did this visit sample the concrete block, or stop at naming it?
- Has any class been awarded, or is the block still unclassified?
What are the typical next steps?
- Treat the stain as a mark, not as a class for the block.
- Tell the solicitor no mundic class was awarded.
- Keep any core test as a separate instruction from this survey.
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
Does granite over the opening mean the walls are the same stone?
No. A granite lintel is the beam over the opening. The walls beside it can still be concrete block, which the stain does not classify. The survey named both and did not sample the block. RICS mundic guidance is for surveyors in the south west, and this home survey has not awarded Class A, B or C.
If the stain is faint, is the concrete cleared?
No. A faint china-clay stain is still only a mark. It does not clear the concrete block and it does not condemn it. The survey did not drill cores and did not award a class. Cornwall Council describes a core test and does not provide it. Faint or strong, the colour is not that test.