Electrics and gas
Shelves have been built across the vent of a boiler cupboard. What combustion-air path is blocked, and what Gas Safe test was not done?
The combustion-air path into the boiler cupboard is blocked where shelves have been built across the vent, and no Gas Safe test was done. Air that should reach the boiler through that opening is obstructed by the shelving. The survey has seen the shelves across the vent. It has not measured the free area left, tested combustion, or checked the flue. A Gas Safe inspection is a different visit. This one did not carry it out.
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?
A boiler in a cupboard often relies on a vent so air for combustion can enter. Shelves fixed across that grille close the route, even if a slot still shows at the edge. The survey can say the vent is covered. It cannot say the boiler is starved, and it cannot say any remaining gap is enough, because it did not test the burn. No fumes on the day is not a combustion reading.
Ask a Gas Safe engineer to inspect the boiler, the vent and the flue as gas work, and do not describe the home survey as that test. Tell the solicitor the report records shelves across a vent. If the shelves are to come out, that is a small building job plus the gas check, not a result already achieved. The survey did not clear the vent and did not certify the appliance.
What should you ask your surveyor?
- Which vent of the boiler cupboard is crossed by the shelves?
- How much of that opening, if any, was still free to see?
- Did you record a visual note rather than a Gas Safe test of combustion air?
What are the typical next steps?
- Treat the combustion-air path as blocked by the shelves.
- Instruct a Gas Safe inspection of the boiler, vent and flue.
- Do not describe the home survey as the gas-safety test.
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 boiler fired during the visit, is the air path acceptable?
No. Firing on the day is not a test of the vent the shelves cover. The survey saw the obstruction and did not measure combustion air or the flue. A boiler can run for a short time in a restricted cupboard. That observation is not a Gas Safe result, and it does not reopen the vent.
Can the shelves stay if a gap is left at one end?
The survey cannot say so. It saw shelves built across the vent and did not measure whatever gap remains. Whether a reduced opening is enough is a gas-safety question for a registered engineer. The home survey did not make that judgement and did not pass the cupboard.