Tackling Heat Loss in Solid Wall Homes
What is internal wall insulation? It is the process of fixing an insulating layer to the internal face of external walls in properties that cannot be treated through cavity fill, typically homes built before the 1920s. This is one of the highest-impact fabric improvements available for older UK homes. According to the Energy Saving Trust, around a third of the heat in an uninsulated home escapes through the walls, making solid wall insulation one of the single biggest efficiency gains available.
Cucumber Eco works with homeowners, landlords, and letting agents across the UK to access internal wall insulation grants through the Warm Homes Plan. Our team manages the process from initial survey through to completed, warranted installation.
Check Your Eligibility
What Internal Wall Insulation Involves
Internal wall insulation is installed room by room by fixing insulating boards or a studwork frame filled with insulation material to the internal surface of external walls. The process typically includes:
- ✓ A detailed survey to assess wall construction and damp risk
- ✓ Preparation of wall surfaces and any remedial damp treatment
- ✓ Fixing of rigid insulation boards or insulated plasterboard to external walls
- ✓ Making good around windows, doors, and skirting boards
- ✓ Replastering and finishing to achieve a smooth internal surface
Internal wall insulation reduces the internal floor area of rooms slightly, as the insulated layer adds depth to the walls. Our surveyors will discuss the most appropriate system for each room and advise on the expected impact.
Impact on Your EPC Rating
For solid wall properties, internal wall insulation typically delivers the largest single improvement to a property's EPC rating of any insulation measure. It can:
- ✓ Raise SAP scores significantly, often by 10 to 20 points
- ✓ Move a property up by one or two EPC bands
- ✓ Cut heat loss through solid walls, around a third of heat escapes through uninsulated walls per the Energy Saving Trust
- ✓ Help solid wall properties achieve or approach EPC band C
- ✓ Satisfy the highest priority recommendation on most solid wall EPC reports
Is Your Property Suitable?
Internal wall insulation is most suitable for properties with solid external walls, including:
- ✓ Properties built before approximately 1920 with solid brick or stone walls
- ✓ Homes where external wall insulation is not feasible (e.g. terraced houses, conservation areas)
- ✓ Any property confirmed to have solid rather than cavity walls
- ✓ Properties currently below EPC band C seeking the most impactful fabric improvement
Our surveyors will carry out a thorough pre-installation assessment to confirm suitability, check for damp, and recommend the most appropriate insulation system for your property.
Typical Savings
Based on a typical solid wall semi-detached house. Actual savings depend on property size, wall area, heating system, and energy tariff.
Grant Funding Through the Warm Homes Plan
Solid wall insulation, including internal wall insulation, is one of the measures supported under the Warm Homes Plan. Where households or properties meet eligibility requirements, the installation can be fully funded. Eligibility is assessed on the basis of:
- ✓ Household income or qualifying benefit status
- ✓ Property postcode (properties in low-income areas may qualify)
- ✓ Current EPC rating (typically below band C)
- ✓ Property type and wall construction (solid wall properties are prioritised)
Because internal wall insulation is a more substantial and costly measure than loft or cavity wall insulation, acting early and securing grant funding is advisable. Where grant funding is not available, 0% finance may be an option through approved lenders, subject to eligibility.
Apply for FundingGet a Free Assessment
We will assess your property and eligibility at no cost and with no obligation.