Age and type of house
Grease staining on the flat's kitchen wall sits beside a flue from the shop below, and the shop was not entered. What path is that stain, separate from the flat's own roof?
The stain reads as a path from the shop flue, not as a leak from the flat's own roof. Grease on the kitchen wall sits beside that flue, which is a cooking path from below. The shop was not entered, so the flue was not followed inside the shop. The survey has not traced the duct, not smelt its way to a roof defect, and not blamed the flat's covering. Separate from the roof, the path on offer is the flue beside the wall. It is a reading of position, not a test of the shop.
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?
Grease is not the usual mark of rain. Rain stains are often tidemarks or salts. A greasy patch next to a flue from a shop kitchen points at cooking effluent, a leaking joint, or condensate from that duct. Because the shop stayed shut, the surveyor could see only the flat's side of the wall. The duct's route, its fan and its condition in the shop are unknown. The flat's roof was not needed to explain a stain that sits on the flue.
Tell the solicitor the stain is recorded beside the shop flue and that the shop was not entered. Ask, through the solicitor, what the lease says about flues that serve another unit. If the grease matters, a contractor who can be admitted to both sides should look at the duct. Do not commission a roof repair on the flat to answer a stain the survey has kept separate from the roof.
What should you ask your surveyor?
- Where did the grease sit relative to the shop flue?
- Was the shop unentered, so the duct inside it was unseen?
- Have you kept this stain separate from the flat's own roof?
What are the typical next steps?
- Read the grease as a flue-side path, not a roof leak.
- Ask the solicitor what the lease says about the shop's flue.
- Get a duct inspection that can include the shop if access is given.
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 flat's roof is old, must it still be the source?
Age of the covering is not a path. The grease sits beside the shop flue, and the shop was not entered. The survey has not promoted the roof into the cause. An old roof can be a separate maintenance point. It is not this stain.
Does a working extractor in the flat clear the shop flue?
No. The flat's own extractor serves the flat. It was not a test of the shop duct, and the shop was not entered. Grease beside that flue remains a flue question. The survey has not swapped the two appliances. They remain different.