Age and type of house
What should you ask about a glazed lantern over a Victorian or Edwardian stair?
Ask for the lantern as its own element. It has glass, a kerb and flashings where it meets the roof, and a leak there drips on the stair, not through the main tiles. The survey should say whether it saw the lantern from the landing, from outside, or both. It should not fold the lantern into a single sentence about the slates.
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?
Lanterns and roof lights over stairs are small, awkward roofs. The putty fails, the flashing lifts, and condensation on the glass can be mistaken for a leak. A home survey from the landing sees stains and the underside. It may not see the kerb safely from the slope. Say which view was taken. A dry landing on the day does not prove the flashing.
This is not a loft-conversion question and not a listing question. Do not assume the house is listed because the stair has old glass, and do not assume the lantern was a later alteration because it looks odd. Describe the glass that is cracked and the timber that is soft. Replacement is a glazing job only after you know whether the frame and the flashing are the real defect.
What should you ask your surveyor?
- Did you see the lantern from inside, outside, or both?
- Is the stain under it, or under the main slope?
- Are you describing cracked glass, failed flashing, or both?
What are the typical next steps?
- Ask a roofer or glazier about the lantern, not only about the main covering.
- Photograph the kerb if it can be seen safely. Do not walk the roof.
- Do not replace every slate because the stair glass is cracked.
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 lantern the same as a dormer bedroom?
No. A lantern lights the stair. A dormer is a different structure. Ask which one the report means.
Does condensation on the glass prove the flashing has failed?
No. Condensation is on the glass. A leak leaves a stain on the lining or the timber. The survey should say which it saw.