Chimneys and parapets
Moss is growing in the flaunching and the pot is still plumb. What maintenance of the flaunching is being described, as against a stack that is leaning?
What is being described is weathered flaunching that is carrying moss, not a stack that is leaning. The mortar crowning the chimney has plants in it, which means that mortar is open enough to hold growth, while the pot itself was seen upright. A leaning stack would be the chimney moving out of plumb. The survey has described moss in the flaunching and a pot that is still straight. It has not called the stack unsafe from moss alone, and it has not tested the flue.
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?
Flaunching is the mortar that beds the pots and sheds water off the top of the stack. Moss in it is a maintenance point: the mortar is weathered. It is not, by itself, a measurement of lean. The surveyor can see a pot that is still plumb and mortar that is hosting growth. Those are two observations. Mixing them into a story of a falling chimney overstates the note. The flue, the mid-feathers and the hidden stack were not opened.
Ask a roofing or chimney contractor to repoint or renew the flaunching if the mossy mortar is to be dealt with, and to say whether the pot bedding is still sound. Keep any flue check as a separate inspection. Tell the solicitor the survey distinguishes weathered flaunching from a leaning stack. Do not report the chimney as leaning when the pot was seen plumb.
What should you ask your surveyor?
- Is the note moss in the flaunching rather than a lean?
- Was the pot still plumb when you saw it?
- Did you leave the flue untested?
What are the typical next steps?
- Describe weathered flaunching, not a leaning stack.
- Ask a contractor to look at the mossy mortar and the pot bedding.
- Keep any flue inspection separate from this visual note.
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Also asked about this
If moss is thick, has the stack moved?
Not on moss alone. Thick growth shows mortar that holds moisture. The pot was still plumb. The survey has not reported a lean, and it has not measured movement of the stack. Weathered flaunching is the maintenance being described, not a stack that is leaning.
Does a straight pot mean the flaunching can be ignored?
No. The pot being plumb answers the lean question. It does not repair the flaunching. Moss in that mortar is still the maintenance the survey described. A straight pot and mossy mortar are two different observations, and only the mortar needs the maintenance note.