Timber decay and woodworm
What should you ask if the subfloor is marked not inspected?
Ask why: no access, a flooded void, a screwed-down hatch, or a risk of disturbing asbestos tiles. “Not inspected” is not a pass. The joists in that void are unknown. If the ground floor matters to you, the next step is access, not a guess.
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?
Suspended timber floors need ventilation. Blocked air bricks are a common note when the surveyor can see the outside but not the void. They can recommend opening the hatch. They cannot describe rot they might have found. The Property Care Association links poor subfloor ventilation to decay. That is a reason to look, when access can be arranged.
Ask the seller to clear the hatch. If the surveyor will return, confirm the fee. If a timber specialist will go in, confirm they will report on ventilation, moisture and the joist ends, not only sell a spray. Solum concrete, debris and a high water table are things they might find. None of those has a standard price.
What should you ask your surveyor?
- Why was the void not inspected, in one sentence I can repeat?
- What outside clues, such as air bricks, did you see?
- Is a return visit worthwhile, or is the limit acceptable for this house?
What are the typical next steps?
- Do not tell yourself the floor is fine because the carpet feels firm.
- Clear the hatch and look, or pay someone to look, if you need to know before exchange.
- Unblock nothing by smashing air bricks. Identify them first. Some holes are vents and some are not.
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 solid floor marked NI for the same reason?
No. A solid floor has no void. NI on a solid floor means the surveyor could not see the surface or the edge they wanted. Read the sentence.
Can you inspect a void that smells of fuel or sewage?
Do not climb into a dangerous void. The limitation may be about safety. Ask a specialist with the right equipment. The surveyor was right not to be a hero.