LANDLORD KNOWLEDGE
Internal wall insulation and EPC improvement
Internal wall insulation can reduce heat loss through suitable walls, but the design and moisture behaviour matter as much as the product.
When is it worth investigating?
Solid-wall homes may merit investigation. Check wall type, exposure, damp, joist ends and historic fabric. Internal work can reduce usable room space and disturb finishes and services.
When might it be the wrong first step?
Resolve causes of moisture first. Thermal bridges at floors, ceilings, windows and partitions need detailing. A thin decorative coating should not be treated as equivalent to a designed insulation system without valid evidence.
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?
Ask for a room-by-room design, ventilation approach, specification, installation evidence and plan for making good. Compare internal and external alternatives.
Further reading: Energy Saving Trust. Guidance checked 4 October 2026. Installation suitability needs a property assessment.