How much does insulation cost in 2026?
Insulation costs vary significantly by type and property. Loft insulation is the cheapest at £300 to £600 for a typical home. Cavity wall insulation costs £400 to £1,500. Solid wall insulation is the most expensive at £4,500 to £13,000 for internal or external options. However, many households can get insulation installed for free through the ECO4 scheme or GB Energy Scheme.
The savings also vary. A detached house saves more than a mid-terrace because it has more exposed wall and roof area. Homes heated by oil or LPG see larger savings than those on mains gas because their fuel costs more per unit. Our calculator factors in your property type and fuel to give you a personalised estimate.
Should I insulate before installing a heat pump?
Yes, almost always. Heat pumps work best in well-insulated homes because they operate at lower temperatures than gas boilers. Better insulation means you need a smaller heat pump (lower cost), the heat pump runs more efficiently (lower bills), and your home stays comfortable at the lower flow temperatures. Our EPC improvement planner can show you the most cost-effective order of improvements for your home.
Types of insulation explained
Loft insulation
The simplest and most cost-effective upgrade. The recommended depth is 270mm of mineral wool. If your loft is easy to access and you are comfortable working at height, this is a common DIY project. Professional installation takes a few hours for a typical home.
Cavity wall insulation
Suitable for homes built after 1930 with unfilled cavity walls. An installer drills small holes in the outer wall, injects insulation material, and seals the holes. The process typically takes two to three hours for a whole house with minimal disruption.
Solid wall insulation
For homes built before 1930 with solid walls (no cavity). Available as internal insulation (boards fitted to interior walls, reducing room size slightly) or external insulation (cladding applied to the outside of the building). Both are effective but significantly more expensive and disruptive than cavity or loft insulation.
Frequently asked questions
How much does loft insulation cost in 2026?
Professional loft insulation typically costs £300 to £600 for a standard home. Many households qualify for free installation through the ECO4 scheme or GB Energy Scheme. DIY loft insulation using mineral wool rolls costs around £5 to £8 per square metre from builders' merchants.
Is cavity wall insulation worth it?
For most homes, cavity wall insulation saves £200 to £500 per year on heating bills, with a typical payback period of 2 to 4 years. It is one of the most cost-effective home improvements available. However, some homes have issues with damp penetration after cavity fill — get a survey from a reputable installer before proceeding.
Can I get free insulation in the UK?
Yes. The ECO4 scheme and GB Energy Scheme provide free or heavily subsidised insulation to qualifying households, particularly those on low incomes or receiving certain benefits. Check our grant eligibility checker to see if you qualify.
Does insulation improve my EPC rating?
Yes, significantly. Loft insulation can improve your EPC rating by 5 to 10 points. Cavity wall insulation can add 10 to 15 points. Solid wall insulation can add 15 to 25 points. For landlords who need to meet minimum EPC standards, insulation is often the cheapest way to improve their rating.