Roofs and flat roofs
Should counter battens, seen beside the eaves ventilator, be treated as a verdict on a gap packed with insulation?
No. Counter battens seen beside the eaves ventilator are not a verdict on a gap packed with insulation. The survey recorded the battens it could see and a ventilator at the eaves. It has not decided that the gap is clear, blocked or packed, unless the report says the packing was actually in view. A ventilator grille on the outside does not prove a path through the insulation. The home survey has not tested airflow. What stays open is whether that gap still lets the slope breathe.
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?
Counter battens stand the tiling battens off the boards so a gap can run up the slope. An eaves ventilator is the inlet at the bottom of that path. Insulation pushed into the eaves can fill the gap even while the outside grille looks open. From the hatch the surveyor may see the near battens and still not reach the packed area. Seeing both parts explains the design. It is not a measurement of the gap. The air path stays unresolved.
Tell the solicitor the airflow path was not tested. Ask the seller whether insulation was added at the eaves and whether the ventilator was meant to stay clear. If the roof void matters, someone needs a look that actually reaches the gap, which this visit may not have done. Do not tell a lender the roof is ventilated because a grille and some counter battens were seen. The packing question is still open.
What should you ask your surveyor?
- Were the counter battens seen, and how far toward the eaves?
- Was insulation actually visible in the gap, or only a risk noted?
- Did the eaves ventilator show an open path or only an outside grille?
What are the typical next steps?
- Do not treat battens and a grille as a ventilation test.
- Ask whether insulation was pushed into the eaves.
- Reach the gap properly before you call the path clear.
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 an open grille on the fascia enough on its own?
An open grille is the outside of the ventilator. Insulation can still pack the gap behind it, and the survey did not test the path. The counter battens show how a gap was intended. They do not prove it is empty. Keep the grille and the hidden gap as different observations.
Does this note decide the rest of the roof insulation?
No. It is about the gap beside the eaves ventilator and the counter battens seen there. Insulation on the flat of the loft is a different comment. The survey has not judged the whole insulation job, and it has not measured a ventilation rate. Only the eaves path is in question.