Damp and moisture meters
Are white salts on brand-new plaster a category of damp?
No, white salts on brand-new plaster are often left as the new coat dries, or as salts move into a fresh finish. They are not, by themselves, a category of rising damp, penetrating damp or condensation. A meter can still respond to them, and that response is not the category.
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?
New plaster holds water from the job. As it dries, harmless salts can crystallise as a white bloom. Old walls also push salts into a fresh coat if the plaster was replaced over masonry that had been wet, even after that wetting has stopped. Hygroscopic salts can keep a meter interested after the wall is dry. The bloom on a three-week-old skim in a dry room is not the same finding as a tide mark with salts at skirting level on an outside wall. The survey should say how new the plaster is and what else was seen.
A visual inspection does not send the salts to a laboratory. It should not invent a damp category from a white dusting alone. If the plaster was part of a damp repair, ask for the paperwork of that repair, and still judge the wall by staining, mould and outside levels today. Brushing the bloom off and finding dry, hard plaster underneath is a different morning from brushing it off and finding the plaster soft and damp again.
What should you ask your surveyor?
- How new is the plaster, and is there a stain as well as the salt?
- Are the salts a light bloom, or part of a tide mark at the skirting?
- Did a meter respond on the new plaster only?
What are the typical next steps?
- Do not name a damp category from white salts on new plaster alone.
- Ask when the plastering was done and what it was meant to cure.
- If the plaster stays soft or the stain returns, then investigate the cause. The bloom was only the clue.
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
Should new plaster be painted straight away?
Paint can trap drying moisture and salts. The survey is not a decorating specification. Blistered new paint is a clue to look again.
Are salts on an old chimney the same as salts on new plaster?
No. Chimney salts have their own storey. New-plaster bloom needs the age of the coat in the sentence.