Age and type of house
A post-war solid floor has heaved and the report mentions possible sulfate. Has a concrete sample been taken?
No. A concrete sample has not been taken. The survey records a post-war solid floor that has heaved, and it mentions possible sulfate as a cause that is not proved. Sulfate can affect some slabs and the material beneath them. It is not something a home survey confirms by looking. Heave can also come from the ground, from a failed drain, or from the way the slab was built. This visit did not drill the concrete and did not test the fill. The floor shape was seen. The chemistry was not.
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?
Heave is upward movement. In a solid floor it may show as a hump, cracked finishes or doors that catch. Possible sulfate is a hypothesis raised where the age and the damage fit a known mechanism, particularly if the material under the slab could be involved. Naming that possibility is not a laboratory result. Without a sample, nobody knows whether sulfate is present, whether any reaction is still active, or whether the heave has another explanation. The report leaves the cause open.
Tell your solicitor the floor has heaved and that sulfate is only mentioned as possible. If you or a lender need the cause, a specialist has to sample and test, which this survey has not done. Do not write that the slab has confirmed sulfate attack. A chemical problem and a one-off movement in the ground are not the same repair. The report has not specified a new slab and has not cleared the floor. Quote the wording as a possibility, not as a test.
What should you ask your surveyor?
- How does the heave show, and is it local or across the whole floor?
- Does the report mention drains or trees as other possible causes?
- Is sulfate clearly marked as possible, rather than as a confirmed result?
What are the typical next steps?
- Quote sulfate as a possibility, not as a test result.
- Tell your solicitor that no concrete sample was taken.
- If the cause must be known, instruct sampling this home survey did not do.
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 heave always mean the material under the slab must come out?
No. That conclusion needs a cause. The survey has not sampled the concrete or the fill, so it has not designed a repair. Some floors are watched and some are rebuilt, depending on tests and on the structure. Do not start from an unproved sulfate label. Get the investigation the report left open.
Can you drill a hole yourself to speed the answer?
Do not. A casual hole is not a proper concrete sample, and it can damage finishes and services in a solid floor. The survey did not take a sample because that is specialist work. If a core is required, a specialist should take it and interpret it. Until then the chemistry stays unknown.