Roofs and flat roofs
Lead is let into a cut in the brick of a chimney and the mortar over the cut is missing. What weather resistance is left, and what hose test was not done?
What is left is lead sitting in an open cut, with the mortar cover gone, and no hose test was done. Lead let into a chase in the chimney brick relies on the mortar over that cut to close the joint against rain. With the mortar missing, the weather resistance at the chase is the bare lead in an open slot, which is not a closed flashing. The survey has seen the cut and the missing mortar. It has not hosed the chimney, has not proved how much water enters, and has not dressed the lead or repointed the chase.
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 chimney flashing fails at the joint with the brick as often as it fails in the apron. The cut is a horizontal or raked slot. Pointing over the lead is what keeps driven rain out of that slot and out of the brickwork behind. Missing mortar leaves the slot open even if the lead itself is still tucked in. From the ground or a ladder view the survey can see the gap.
Ask a roofer to repoint or recut and repoint the chase, and to say whether the lead is still properly let in. Tell the solicitor the weather resistance left is an open cut, and that no hose test was done, so nobody has a filmed leak from this visit. Do not accept a smear of mastic as the survey's finding. The inspection did not test the joint with water and did not repair it.
What should you ask your surveyor?
- Where is the mortar missing along the cut that holds the lead?
- Is the lead still let into the brick, or has it also come out?
- Did you carry out any hose test of the chimney?
What are the typical next steps?
- Treat the open cut as the weather resistance that is left.
- Do not invent a hose-test result.
- Ask a roofer to make the chase weathertight.
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 lead still looks thick, is the joint closed?
No. Thick lead can still sit in a cut whose mortar cover is missing. The weather resistance left is that open slot, not a sealed flashing. The survey did not hose the chimney, so thickness was not a water test.
Does soot inside the loft prove this cut has leaked?
Not by itself. Soot can be old chimney residue. The survey's point is the missing mortar over the lead, and the hose test that was not done. Soot is not that test and does not measure weather resistance at the cut.