Damp and moisture meters
Can a raised path or a render coat let damp in by bridging the damp-proof course?
Yes. If soil, a patio or render sits above the damp-proof course, rain and ground moisture can cross into the wall above the course. That is bridging, not proof that the course itself has failed. A home survey should say what it could see outside, and a meter cannot separate the two.
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?
A damp-proof course is a barrier near the base of a wall. It only works if the ground, the path and the render stay below it, and if nothing else connects the wet outer face to the inner plaster. A surveyor standing outside can often see a path that has been built up, a flower bed against the brick, or render taken down to the paving. They cannot see whether the original course is continuous inside the wall.
Government damp guidance for rented homes starts with the cause, not with a product. The Property Care Association likewise treats the building defect as the thing to find. Lowering a path or cutting render back is a different job from injecting a new course. Costs vary with the length of wall and what the path is made of. Ask for that scope in writing before anyone prices an injection.
What should you ask your surveyor?
- Is the outside ground, path or render higher than the damp-proof course?
- Did you see a tide mark inside, or only a meter reading at the skirting?
- Would you still suspect the course if the bridge outside were removed?
What are the typical next steps?
- Photograph the outside ground against the brick course before anyone digs.
- Do not commission an injected damp-proof course for a path that is simply too high.
- If the purchase depends on the cause, agree an investigation that looks at the outside levels as well as the plaster.
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 a cavity wall still need the ground kept low?
Yes. A cavity does not replace the damp-proof course at the base of each leaf. Debris or a high path can wet the inner leaf anyway.
Is render always a defect?
No. Render is a finish. It becomes a damp path when it crosses the course or traps water against a cracked wall. The survey should say which of those it saw.