Damp and moisture meters
What did the visit record about a magnesite floor, about salt deposits, and about a basement the covering is stuck to?
The visit recorded a magnesite floor, salt deposits on it, and a basement covering that is stuck down. Magnesite is an old jointless floor that can hold moisture and show salts at the surface. Those salts were something the surveyor could see. The covering was not lifted, so the floor it is stuck to was known only at edges or where salts had come through. The survey has not tested what the salts are, has not decided why they are forming, and has not called the basement dry underneath.
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?
Magnesite was laid as a smooth floor over a base, often in service rooms and basements. Moisture moving through it can break the surface down and leave powdery salts. A stuck covering stops the surveyor seeing most of that floor. Salts at a seam or a skirting show that something is coming through at that point. They do not map the whole basement, and they do not name the salt. The visit recorded the material, the deposits and the fact that the covering stayed down.
Tell the solicitor the covering was stuck, so the basement floor has not been fully seen. If the salts concern you, take advice before anyone lifts the finish. The survey has not specified removal, and it has not tested the deposits. Do not read the salts as proof that a damp-proof layer has failed under the whole basement. The note is the surface that was visible and the covering that was left in place. The cause stays open.
What should you ask your surveyor?
- Where were the salts: at seams, at skirtings, or across open magnesite?
- What covering is stuck down, and was any edge already loose?
- Was the base under the magnesite visible anywhere?
What are the typical next steps?
- Keep the magnesite, the salts and the stuck covering as three limits.
- Tell the solicitor the floor under the covering was not exposed.
- Take advice before anyone lifts the stuck finish.
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
Do the salts prove the magnesite floor has failed?
They prove salts were visible. They do not prove the whole floor has failed, and the survey did not test what the deposits are. Magnesite can show salts when moisture moves through it. The covering stayed stuck, so most of the floor was hidden. The visit recorded what came through, not a full account of the base.
Is the stuck covering keeping the basement dry?
The survey has not said that. A stuck covering hides the magnesite and can also hold moisture against it. Salts at the surface show moisture is moving somewhere. The visit did not lift the covering and did not test the floor. Whether the sheet is protecting the floor or trapping damp is still open.