Age and type of house
What should you ask if a 1930s house has a springy timber ground floor?
Ask whether the surveyor could see the void. A suspended timber floor is carried on joists over air bricks. Spring can be ordinary, or it can be a joist, a sleeper wall or rot in a damp void. If the carpets stayed down and the vents were buried, the floor was not proved. NI is not a pass.
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?
Air bricks blocked by a patio are a common reason the void is damp. The Property Care Association links fungal decay to moisture. The surveyor who cannot lift the floor should not sell a spray treatment. They should say what they could not see.
A carpenter looks at access. A drain firm looks at a leak under the floor only if you instruct a test. Those are not in the survey fee. No price for replacing joists is stated here. Do not lift a finished oak floor before exchange just to settle nerves.
What should you ask your surveyor?
- Were air bricks clear?
- Did you lift any boards or only walk the carpet?
- Is the spring local or across the room?
What are the typical next steps?
- Find the air bricks outside before you commission anything.
- If the void is NI and you need it, agree an opening-up visit.
- Do not block the vents with a new path after you move in.
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 concrete floor in a 1930s house a warning?
It may be original or a later replacement. The survey should say if it could tell. A concrete floor can hide a damp slab. It is not automatically a repair.
Does bouncy always mean rot?
No. Span and boarding matter. Soft, musty and a closed void is when you ask for a proper look.