Electrics and gas
A boiler is fixed to the party wall and the neighbour's side was not seen. What flue path on their side is unknown?
The flue path on the neighbour's side of the party wall is unknown. The boiler is fixed to that wall, and the survey did not see the neighbour's side, so it cannot say where the flue runs, where it ends, or what openings it passes over there. The survey has recorded a boiler on the party wall. It has not entered the neighbour's room, has not commissioned a gas safety check, and has not decided the flue is safe or unsafe. The flue might cross the wall, rise in a stack, or discharge somewhere this visit never reached. That path is the unknown.
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 boiler on a party wall may take its flue through the wall, up a shared stack, or along a route that only shows next door. From your side the survey can see the case and the pipes in your room. The neighbour's side is another home. Without access, the terminal, the relation to their windows, and the state of a shared stack stay unseen. Guessing a route from the badge on the boiler would invent the thing the report has left unknown.
Ask the solicitor about access to the neighbour's side if the flue route has to be known, and ask a Gas Safe registered engineer to inspect the boiler and its flue. The home survey has not commissioned that check. Do not tell a lender the flue ends correctly because the boiler looks tidy on your side. Tidiness is not a view of the neighbour's wall. Gas safety is that engineer's inspection. This report has not carried it out.
What should you ask your surveyor?
- Was the neighbour's side of the party wall unseen?
- Which part of the flue path is therefore unknown?
- Did you leave any gas test uncommissioned?
What are the typical next steps?
- Treat the flue path on the neighbour's side as unknown.
- Ask a Gas Safe engineer to inspect the boiler and the flue.
- Do not infer the terminal from your side of the wall alone.
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 alarm in your room stays quiet, is the neighbour's flue fine?
A quiet alarm on the day is not a view of the neighbour's side and not a gas test. The flue path next door remains unknown. The survey has not commissioned a gas safety check and has not seen where the flue goes on their wall. An alarm in your room does not describe their openings. The path stays unknown.
Does a neat seal on your side prove the route past the wall?
No. A seal you can see is on your side. The boiler is fixed to the party wall, and the neighbour's side was not seen, so the path beyond is still unknown. The survey has not tested the gas and has not followed the flue next door. A tidy joint is not that missing view.