LANDLORD KNOWLEDGE
Cavity wall insulation and your EPC
A suitable unfilled cavity may offer an improvement opportunity. A cavity-wall description on an EPC does not itself confirm that filling is appropriate.
When is it worth investigating?
A survey should establish cavity condition, existing fill, wall ties, exposure and moisture risks. Partial walls and extensions may differ from the original home.
When might it be the wrong first step?
Do not infer an empty cavity merely because the EPC says “assumed”. Existing fill, defects, unsuitable exposure or rubble can change the recommendation. Resolve defects and check installation suitability.
How many EPC points could it add?
There is no universal points award. The current property, existing measures, installation specification and assessment methodology all matter. Use the recorded recommendation sequence or an assessor-reviewed scenario; do not add independent estimates together as a guaranteed result.
How much should you allow?
See the published cost benchmarks and request a quotation for the actual scope. The price of a measure is different from the cost of achieving a target rating.
What should happen first?
Obtain evidence of the survey, proposed system, installer suitability and completion. Confirm exactly which wall areas are included.
Further reading: Energy Saving Trust. Guidance checked 4 October 2026. Installation suitability needs a property assessment.