Age and type of house
The rear addition is a single leaf of brick and the main house is thicker. Why should a damp reading in the addition stay in the addition?
A damp reading in the addition should stay in the addition because that rear wall is a single leaf of brick and the main house is a thicker, different wall. Moisture in the thin leaf can come from rain through the brick, from ground levels, or from a detail the front does not share. The survey has not shown that the same reading applies to the main house. Copying it across would turn one wall's result into a diagnosis of another wall that was not that leaf.
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?
Rear additions on Victorian terraces are often a single leaf, with no cavity and with more exposure to weather than the principal rooms. They get wet for local reasons: a thin wall, a roof that drips at the back, a high path. The main house can be thicker brick with its own damp-proof course and its own condition. A meter or a stain in the addition is evidence about the addition. The mechanism has to be described there. It is not a licence to condemn the front elevation.
Ask for the damp comment to name the rear addition, and tell your solicitor the same limit if a specialist quote arrives for the whole house. A damp specialist, if you instruct one, should start from the single-leaf wall that produced the reading. Do not accept a treatment plan that silently spreads to walls the survey did not implicate. The home survey has not tested every wall by looking at this one.
What should you ask your surveyor?
- Was the damp reading taken on the single-leaf addition, not the main wall?
- What local details, such as ground level or a dripping roof, sit at that leaf?
- Have you kept the main house out of this damp comment?
What are the typical next steps?
- Keep the damp finding inside the rear addition.
- Do not copy it onto the thicker main walls.
- Ask any damp specialist to start from the single-leaf wall.
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 addition and the main house share a door, is the damp shared too?
No. A doorway joins the rooms. It does not make the walls the same construction. The reading belongs to the single leaf unless the survey actually found damp in the thicker wall as well. The doorway joins rooms. It does not join the two wall types.
Does one high reading mean rising damp in the whole terrace?
No. One reading in a thin rear leaf does not diagnose the terrace. The survey has not transferred that result to the main house, and you should not do it either. This reading stays on the thin rear leaf alone.