Insulation Cost Calculator
Work out how much it will cost to insulate your home, and how quickly you will earn it back through lower energy bills. Pick your property type, choose the insulation you need, and get a full cost and savings breakdown.
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How this calculator works
Our insulation calculator estimates the cost and energy savings for different types of home insulation based on your property type, age, size, and current insulation levels. You tell us what you already have in place, and the tool identifies which upgrades would make the biggest difference, calculating installation costs and annual bill savings for each one.
The calculator covers loft insulation, cavity wall insulation, solid wall insulation (internal and external), floor insulation, and draught proofing. For each option, it estimates the payback period so you can see which improvements pay for themselves fastest. It also flags potential grant eligibility under the ECO4 and Great British Insulation Scheme programmes.
Energy savings estimates are based on data from the Energy Saving Trust and adjusted for your property type and heating system. Actual savings depend on your specific home, how you use your heating, and the quality of the installation. These figures are for budgeting purposes - a proper home energy assessment will give you a more precise picture.
Frequently asked questions
How much does home insulation cost in the UK?
It depends on the type. Loft insulation is the cheapest at around £300 to £1,000 for most homes. Cavity wall insulation typically costs £400 to £1,200. Solid wall insulation is the most expensive, ranging from £4,000 to £25,000 depending on whether you go internal or external. Draught proofing is often under £500 and is a good place to start.
Which insulation gives the best return on investment?
Loft insulation and draught proofing offer the quickest payback, typically paying for themselves within 2 to 4 years through lower energy bills. Cavity wall insulation is also very cost-effective with a payback period of around 3 to 5 years. Solid wall insulation costs more upfront but can save £300 to £500 a year on heating, so the payback is usually 15 to 30 years.
Can I get a grant for insulation in 2026?
Yes. The ECO4 scheme and the Great British Insulation Scheme (GBIS) can cover part or all of the cost for qualifying households. You may be eligible if you receive certain benefits like Universal Credit or Pension Credit, or if your home is in council tax band A to D in England. Your energy supplier can tell you if you qualify, or you can check through the gov.uk Simple Energy Advice service.
How do I know if my walls are cavity or solid?
Most homes built after the 1930s have cavity walls. If your home was built before the 1920s, the walls are almost certainly solid. You can check by looking at the brickwork on an external wall. If the bricks are all laid lengthways in a uniform pattern, you probably have cavity walls. If you can see a mix of long and short bricks (a Flemish or English bond pattern), the walls are likely solid. Wall thickness is another clue: cavity walls are usually over 260mm thick, while solid walls are around 230mm.
How much can insulation save on my energy bills?
A well-insulated home can save hundreds of pounds a year. Loft insulation typically saves £150 to £300 per year. Cavity wall insulation saves around £200 to £400. Solid wall insulation can knock £300 to £500 off your annual heating bill. Even simple draught proofing can save £50 to £150 a year. The exact savings depend on your home, your heating system, and how much energy you currently use.