Wall ties and cavity insulation
Blown fibre is packed inside the electricity meter box. What does that say about cavity fill, and what does it not prove about the ties?
It says cavity fill is present at least where the electricity meter box opens into the wall. Blown fibre packed in that box is insulation that has reached an opening cut into the cavity. It does not prove the fill is complete, even, or dry through the rest of the walls, and it proves nothing about the ties. The ties were not seen and were not tested. The survey records fibre at the meter. It has not inspected the cavity or the metal that should tie the leaves.
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?
Meter boxes often bridge or cut the cavity, so they are one of the few places fibre shows without a purpose-made inspection hole. Fibre there supports a conclusion that a blown fill was installed in that area. It cannot map every elevation, and it can itself hide the ties a surveyor would otherwise hope to glimpse. Energy Saving Trust describes cavity wall insulation as a measure for suitable walls. This visit did not audit that installation and did not carry out a tie survey.
Ask the solicitor for any cavity-insulation guarantee and installer papers, and keep them separate from this observation. A lender may want those papers, or a proper cavity inspection, where ties are unproven. Do not pull the fibre out of the meter box. The electrics were not tested either. The home survey’s point is narrow: fill is visible at that opening, and the ties remain uninspected.
What should you ask your surveyor?
- Where exactly is the blown fibre described?
- Which walls, if any, are said to be unconfirmed for fill?
- What sentence leaves the ties uninspected?
What are the typical next steps?
- Read the fibre as fill at the meter opening only.
- Ask for any insulation guarantee and installer papers.
- Do not treat the fibre as a tie inspection.
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
Does fibre in the box mean every wall is filled?
No. Fibre packed in the electricity meter box shows fill at that opening. It does not map the other elevations, the gables or the areas above openings. Gaps, settlement of the fibre, or empty bays would not show in the box. The survey has not claimed the whole cavity is filled, and it has not proved anything about the ties.
Were the electrics tested because the box was open?
No. An open meter box that contains blown fibre is not an electrical test. The survey did not test the electrics and did not inspect the ties. It recorded insulation visible in that box. Any check of the installation needs an electrician instructed for that purpose, reported separately from this note.