Chimneys and parapets
What changes if the pots have been removed and the flaunching is left open?
An open hole at the top of a stack lets rain into the flue. The flaunching is the mortar that should weather the top and hold the pots. If the pots are gone and the holes are not properly capped and ventilated, the breast below can become wet even though nobody is lighting a fire.
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?
Surveyors see this from the ground when the crown of the stack is visible. They cannot always see whether a cap was fitted below the rim, or whether the flue is open to a bedroom. Rain down an unused flue is a common cause of staining on a breast. It is not rising damp. Approved Document J deals with combustion appliances and how flues are constructed for new work. It does not certify this old stack from the pavement.
Capping and ventilating is ordinary chimney work. Doing it badly, with a solid plug and no air, can trap damp. The survey will not design the cap. Ask a chimney contractor what they would fit, and ask the surveyor whether the stains inside match an open crown. There is no single published price in the RICS consumer guide.
What should you ask your surveyor?
- Are the flues open at the top, capped, or impossible to see?
- Is there staining on the breast below those flues?
- Would you want the flues ventilated rather than sealed solid?
What are the typical next steps?
- Do not fill the holes with newspaper and mortar as a weekend repair before you own the house.
- Photograph the crown. A pot lying in the garden is not a cap.
- Keep this separate from any damp-proof course quote for the ground floor.
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
Is a missing pot a rating by itself?
Only the surveyor’s report can rate it. A missing pot is a defect in the weathering. Whether it is urgent depends on whether water is getting in, which the definition of the ratings turns on.
Can rain down a flue wet a party wall?
It can wet the breast it travels. In a terrace, ask whether the flue is yours before anyone caps a shared stack.