Non-standard construction
The report places woodwool slabs, a roof deck and a span the slabs' name does not prove in one paragraph. Which of those were inspected, and which were merely named?
The slabs and the deck were inspected only as far as they could be seen, and the span was merely named. Woodwool slabs used as a roof deck were recorded from the surfaces available, usually the soffit or an edge. The name of the slab does not prove how far it spans, what supports it or whether it has lost strength. The survey has not load-tested the deck and has not opened the build-up. Seeing the product is not a structural calculation.
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?
Woodwool is a slab of wood strands bound with a cement paste, used in some roofs as a deck or as a permanent lining. It can be stained by roof leaks, softened at edges or left spanning further than a later alteration allows, but none of that is settled by reading the word on a drawing or recognising the texture. This visit did not measure the span, did not find the bearings and did not weigh the roof. The paragraph lists items. It does not grade their capacity.
Ask the solicitor for original drawings, any replacement-roof specification and photographs of the deck from above. A structural engineer can check span and condition if the roof is to be relied on or recovered. That check is not this survey. Tell a lender the woodwool was identified as a material where it was seen, and that span and strength were not proved. Do not accept a covering quote that assumes the deck is fit just because it has a name.
What should you ask your surveyor?
- Were the woodwool slabs seen at a soffit or edge, rather than opened?
- Was the span named without being measured?
- Has the deck been left without a load test?
What are the typical next steps?
- Separate the seen slabs from the unproved span.
- Ask the solicitor for drawings of the roof deck.
- Refer span and strength to a structural engineer if the roof must be relied on.
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
Does a dry ceiling under woodwool prove the deck is strong?
No. A dry soffit says nothing about span, bearings or loss of section inside the slab. The survey did not measure the deck and did not open the build-up. Staining would be a moisture note, and the absence of staining is not a structural clearance. Strength stays outside this report.
Can insulation laid over the slabs hide a failing deck?
Yes, it can hide the top face, and this visit did not lift insulation or felt to see it. The slabs were noted from what was visible, not from a stripped deck. Moisture trapped above a lining would not necessarily show below on the day. Ask a roofer to see the top if the covering will be replaced. The survey has not done that.