Chimneys and parapets
The hearth has lifted and the survey mentions sulphate, without a sample. What laboratory test has not been done on that concrete?
The laboratory test of that hearth concrete has not been done. The hearth has lifted, and the survey mentions sulphate without a sample, so the lift is a thing seen and the sulphate is a name without a specimen. A laboratory would need a sample of the concrete before it could say sulphate had expanded it. The survey has not taken that sample and has not had the test done. It has not decided that sulphate caused the lift, and it has not ruled sulphate out. Mentioning the word is not the test.
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?
Hearths lift for more than one reason: heat, a poor base, moisture, or a chemical change in the concrete people sometimes call sulphate attack. Those causes are not separated by looking at a raised slab. Without a sample there is nothing for a laboratory to test, so the chemistry of this concrete is unknown. The survey should keep the lift as the observation and the sulphate remark as an untested possibility. It should not be read as a result.
Ask a specialist, if the cause matters, to sample the concrete and have a laboratory test it. Tell the solicitor the survey has not done that test and has not proved the cause of the lift. Do not price a chemical remedy off a word in the report. Do not tell a lender the hearth failed a laboratory test. There was no sample, so there was no test, and the lift is still only a lift until someone tests the concrete.
What should you ask your surveyor?
- What movement of the hearth did you actually see?
- Was any sample taken for a laboratory test?
- Is sulphate a possibility you have left untested?
What are the typical next steps?
- Treat the laboratory test of the hearth concrete as not done.
- Keep sulphate as an untested mention, not a result.
- Have the concrete sampled if the cause of the lift must 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
If the hearth is cracked as well as lifted, has sulphate been proved?
No. Cracks and a lift are what the survey could see. They are not a laboratory result. Sulphate was mentioned without a sample, so the test on that concrete has not been done. The cause stays unproved. The raised concrete still has no specimen behind the word sulphate.
Can the chimney flue be swept instead of testing the concrete?
Sweeping the flue, if it is needed, is a different job. It does not sample the hearth and it does not complete the laboratory test that has not been done. The lift of the concrete is still chemically unexplained. Flue sweeping would leave this hearth chemically untested.