Roofs and flat roofs
Where a report pairs missing lime torching with the loft side of the slates, what stays open about snow dust on the ceiling joists?
What stays open is how the snow dust on the ceiling joists got there, and whether missing lime torching on the loft side of the slates is the path. The report paired those observations. It has not decided that snow blew in because the torching is gone, and it has not decided that the slates above are failed. Dust on joists shows fine material settled inside. Missing torching shows a gap in an old mortar coat. The link between them was not tested.
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?
Lime torching was spread on the back of slates to cut wind-driven snow before underfelt was usual. Where it has fallen, the loft side of the slates is bare and draughts can carry fine snow that later shows as dust on the joists. The same dust can come from an open eaves, a ridge gap or an unsealed hatch. The surveyor sees bare slate backs in the bays reached, and dust where it lies. That is two facts, not a weather test of every bay.
Ask the solicitor whether the seller has seen snow or dust indoors, and whether felt was added when torching fell. A roofer can relate the bare backs to the covering outside. The home survey has not made that link and has not said the ceiling is unsafe. Do not sweep the dust away in your mind and call the torching note closed. Both observations stay until someone traces the path.
What should you ask your surveyor?
- Where was lime torching missing on the loft side of the slates?
- Where was the snow dust, and how widespread was it on the joists?
- Does the report keep cause and path undecided?
What are the typical next steps?
- Keep the missing torching and the dust as linked but untested.
- Ask the seller whether snow has been seen in the loft.
- Let a roofer trace the path rather than assuming one gap.
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 snow dust the same as a ceiling collapse?
No. Dust on the joists is fine material that settled. It is not a structural failure of the ceiling. The survey recorded it beside missing torching. It did not test the plaster or the joists for strength. Treat it as evidence that something has blown in, not as a verdict that the ceiling has failed.
If torching is missing, must underfelt be absent too?
Missing torching shows the mortar coat has gone in the bays that were seen. Felt can still exist in other bays, or not exist at all. The lamp did not map every slope. The report has not decided the underlay for the whole roof from the patches of bare slate.