Chimneys and parapets

What is chimney flaunching, and can it fail while the pots still look upright?

Flaunching is the mortar that weathers the top of a stack and beds the pots. It can crack or wash out while the pots still look straight from the street. Water then gets into the top of the stack and down into the bedrooms.

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 home survey sees the stack from a distance unless there is a safe closer view. The surveyor may report uneven flaunching, open joints or a lean. They will not usually stand on the pot. A straight pot is not a sound crown. The inside clue is damp or salts on the chimney breast, which can be old soot salts as well as fresh rain.

Re-flaunching needs safe access. The price is a roofing or chimney contractor’s quote for this stack, including scaffold or a platform if they say they need it. Do not use a neighbour’s price. If the flue is in use, a combustion check is a different job from the mortar. Approved Document J and a competent installer cover appliances. The survey does not sweep the flue.

What should you ask your surveyor?

Could you see the flaunching, or only the pots from ground level?
Is the breast damp, salty, or both?
Is the flue in use, and did you exclude a combustion test?

What are the typical next steps?

Ask a chimney contractor to quote for access and for the flaunching separately from any pot replacement.
Do not assume a straight pot means a dry bedroom.
If you will use the flue, instruct a sweep and the right competent person. That is not the home survey.

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

What is a haunching?

People use the word loosely for the same crown mortar. Ask the surveyor which mortar they mean: the crown, the pots, or the mid-stack joints.

Can a cowl hide failed flaunching?

A cowl sits on the pot. It does not repair the mortar around the pot. It can also hide a broken pot edge from the ground.