Timber decay and woodworm
A deck blocks the air bricks along the back wall. Why is that a timber-floor question and not a defect of the deck boards themselves?
It is a timber-floor question because the deck is blocking the air bricks that ventilate the underfloor void, not because the deck boards have been found defective. The boards may be perfectly sound and still sit across the vents. The defect that matters to the house is the stopped air path under the suspended floor. The survey saw the deck covering those bricks. It has not said the deck timber is rotten, has not graded the boards, and has not inspected the joists in the void. The deck is the obstruction. The floor ventilation is the issue.
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 only work while they are open to the outside. A deck built tight against the wall, or with its fascia across the holes, closes them. The floor inside can then mirror the stale void you would get from missing bricks, even though the deck itself is a garden structure. Reporting this as a failed deck sends a carpenter to replace boards that were not the finding. Reporting it as a blocked vent sends them to the holes. The survey made the second point.
Have the deck altered so the air bricks are open again, by a notch, a gap or a relocated edge, and then see the vents clear. A timber specialist only needs to come for the floor if there is a separate reason to suspect the joists. Tell the solicitor the note is blocked ventilation, not a defective deck. The survey has not specified new deck boards and has not specified a new floor. Do not rip the deck up on a viewing.
What should you ask your surveyor?
- Which air bricks does the deck cover along the back wall?
- Did you find any defect in the deck boards themselves, or only the blockage?
- Is the concern the underfloor void rather than the deck surface?
What are the typical next steps?
- Treat the deck as a blockage of the air bricks, not as failed boards.
- Alter the deck so those air bricks can breathe again.
- Do not replace the deck boards on this note alone.
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
If the deck boards are rotten, is that this finding?
Rotten boards would be a separate defect if they were seen. This note is the deck blocking air bricks, which is a timber-floor ventilation question. The survey has not used the blockage to condemn the boards. Asking about it again later still leaves this deckboard point outside what the survey decided.
Can the air bricks be ignored if the deck is only just covering them?
A partial cover can still stop the opening. The survey saw the bricks blocked along the back wall. How complete the cover is does not turn the note into a defect of the deck boards. The home survey itself did not pursue this partialcover question any further than the visit.