Chimneys and parapets
What should you ask if mortar has been smeared over the top edge of a chimney flashing?
Ask whether the lead can still shed water or the chase is buried. Mortar over the top of a flashing can close the joint the lead was dressed into, so water behind the smear cannot escape on the face of the lead, even though the flashing may still be present. The survey sees the smear if it was visible and does not rake the joint out.
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 proper chase is pointed so the lead stays wedged and the joint weathers. A later smear, often from a quick repoint, can bridge over the edge and trap water down the back of the stack. The tiles can look even and the pots can look straight. A home survey should describe mortar burying the flashing where that was in sight, and should not pretend to have seen the chase under the smear. From the ground the top edge is a thin line and is often missed.
The repair is to rake the bury back and redress or rewedge the flashing, not to add more mortar. There is no RICS price. If the lead itself is split, that is a further finding once the edge is opened, which the survey has not done. Ask a roofer to include each stack they can reach. Do not confuse this with a cement fillet used instead of lead. Here the sheet is there and the mortar is on top of it.
What should you ask your surveyor?
- On which stacks is the flashing edge buried in mortar?
- Did you see lead at all, or only the smear?
- Are the side soakers a separate, unseen item?
What are the typical next steps?
- Ask for the chase to be opened and redressed, not for another coat of mortar.
- Do not call the flashing missing if the sheet is visible below the smear.
- List each stack. A front stack does not prove the rear.
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 pointing over a flashing always a defect?
Neat pointing that holds the lead in a chase is normal. A smear that caps the edge and traps water is the problem. Ask which was seen.
Does this make the flue unsafe?
No. It is a weather detail. Appliance safety is not decided by mortar on a flashing.