Wall ties and cavity insulation

Does an unfilled cavity in an early 1930s house need a condition rating 3?

No, not by itself. An empty cavity of that age is not a defect, and condition rating 3 is for something serious, urgent, or both, which an unfilled cavity is not. The survey might still use rating 3 for cracks, failed ties or damp if it actually found them. Those are different findings from the simple fact that nobody has injected insulation.

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?

Early cavity houses were built with an empty gap and have stood that way for decades. The Energy Saving Trust does not treat that empty gap as a fault that must be filled before a house can be bought. Filling is an improvement, with conditions about the cavity and the wall, not a repair of a defect that exists merely because the void is void. A home survey rates condition. It is not an energy audit, and it does not fail a wall for still matching the way it was built.

Read the rating against the words. If the wall is straight, the mortar is reasonable, and the only remark is “cavity not insulated”, that remark is not a rating 3. If the same wall has horizontal cracking or a bulge, the rating belongs to that defect, not to the absence of foam beads. Do not ask the seller to fund cavity insulation as if the survey had ordered an urgent repair. Do not skip a real tie comment because you have correctly refused to treat empty as urgent. Ask the surveyor which sentence the number belongs to.

What should you ask your surveyor?

Is any rating on this wall for the empty cavity alone, or for a defect you saw?
Did you see ties, cracks or damp, or only an unfilled cavity?
Please confirm an empty 1930s cavity is not, by itself, rating 3.

What are the typical next steps?

Do not demand insulation as a rating 3 repair when the cavity is simply empty.
Do follow up a separate comment about ties, cracks or damp.
If you want the cavity filled later, that is an improvement after checks, not a condition the survey has failed.

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 empty cavity a rating 2 instead?

Not automatically. Rating 2 is for a repair that is not serious or urgent. An empty cavity may need no rating at all. Ask what the report actually did.

Does a modern filled cavity make the 1930s house defective for being different?

No. Different age, different build. The comparison is not a defect.