Wall ties and cavity insulation

Can cavity insulation hide the condition of the wall ties from a visual inspection?

Yes. Foam, beads or fibre in the cavity can cover the ties, so a camera cannot see them properly. A visual home survey already cannot see them. Insulation makes a later borescope harder, not easier.

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?

The Energy Saving Trust’s cavity insulation advice says the cavity should be assessed before it is filled, including whether it is wide enough and clear, and that damp and defective brickwork should be dealt with first. It does not say a home survey can judge the ties through the insulation afterwards.

If the report suspects tie failure and the cavity is full, tell the specialist that before they quote. They may need more openings, or they may say the inspection is limited. Do not assume the insulation must be removed on day one. Ask what they need to see. Removal and refill, if required, is a separate specification and a separate price.

What should you ask your surveyor?

Do you know the cavity is filled, or is that a guess from drill holes?
Would a borescope still see the ties, in your view, or are you saying it might not?
Are there visual clues on the outside that do not depend on seeing the metal?

What are the typical next steps?

Show the specialist any drill-hole patterns and the survey wording before they book.
Do not strip insulation because of a worry. Ask whether the ties can be assessed another way.
Keep the damp questions separate. Wet insulation is not the same defect as a rusty tie, even if both can exist.

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

Do drill holes prove the cavity was filled?

They suggest someone drilled it. They do not prove what was injected, whether it is still there, or whether it slumped. The specialist or the installer’s certificate is the better record.

Should the seller produce a CIGA guarantee?

Ask for whatever guarantee exists. A guarantee covers what it covers. It is not a tie inspection.