Home Insulation Costs UK 2026: Types, Prices & Savings Guide
Insulating your home is one of the most effective ways to reduce energy bills and improve comfort. Costs range from around £300 for loft insulation up to £13,000 or more for external solid wall insulation, depending on the type and size of your property. With 0% VAT on insulation until at least March 2027 and grants available through the Great British Insulation Scheme, now is a good time to invest.
Insulation Costs at a Glance
| Insulation Type | Typical Cost | Annual Saving | Payback |
|---|---|---|---|
| Loft insulation (270mm) | £300â£600 | £200â£310/yr | 1â3 years |
| Cavity wall insulation | £450â£1,500 | £185â£395/yr | 2â4 years |
| Solid wall (internal) | £4,000â£8,000 | £270â£475/yr | 10â18 years |
| Solid wall (external) | £7,500â£13,000 | £270â£475/yr | 16â27 years |
| Floor insulation | £500â£1,500 | £40â£70/yr | 8â20 years |
All costs include 0% VAT (valid until March 2027). Savings based on Energy Saving Trust data for a typical semi-detached home.
Loft Insulation
Loft insulation is the easiest and most cost-effective upgrade for most homes. Topping up existing insulation to the recommended 270mm typically costs £300 to £600, depending on the size of your loft and ease of access. If you have no existing insulation, expect to pay closer to £500 to £800.
The savings are significant: the Energy Saving Trust estimates you could save £200 to £310 per year on a typical semi-detached home, meaning loft insulation often pays for itself within two winters. It also makes a noticeable difference to comfort, keeping bedrooms warmer in winter and cooler in summer.
For a detailed breakdown, see our loft insulation cost guide.
Cavity Wall Insulation
Most UK homes built between the 1920s and 1990s have cavity walls â two layers of brick with a gap between them. Filling this cavity with insulation typically costs £450 to £1,500 and takes a professional installer just a few hours. The process involves drilling small holes in the outer wall and injecting insulation material, then sealing the holes.
Annual savings range from around £185 for a mid-terrace property up to £395 for a detached house, giving you a payback period of just two to four years. Cavity wall insulation is one of the most commonly funded measures under the Great British Insulation Scheme.
Read our full cavity wall insulation cost guide for more details on costs, suitability, and potential issues to watch for.
Solid Wall Insulation
Homes built before the 1920s typically have solid walls with no cavity to fill. Insulating solid walls is more expensive but can deliver significant savings, particularly for older, draughty properties. You have two options: internal wall insulation (fitting insulated boards to the inside of external walls) or external wall insulation (adding a layer of insulation to the outside of the building, finished with render or cladding).
Internal solid wall insulation costs £4,000 to £8,000 and slightly reduces room sizes but avoids changing the exterior appearance. External insulation costs £7,500 to £13,000 but can also improve the look of your home and fix issues like damp or cracked render. Both approaches can save £270 to £475 per year on heating bills.
Floor Insulation
Insulating under suspended timber floors costs £500 to £1,500 for a typical home. Savings are more modest at £40 to £70 per year, but floor insulation improves comfort noticeably â cold floors are one of the most common complaints in older homes. Solid concrete floors can also be insulated, but this is usually only practical during a renovation as it involves raising the floor level.
Grants and Funding
Several government schemes can help with insulation costs. The Great British Insulation Scheme (GBIS) provides funding for cavity wall, loft, and solid wall insulation for eligible households â typically those in lower council tax bands or on qualifying benefits. The Warm Homes: Local Grant offers up to £15,000 for energy efficiency improvements for lower-income homeowners.
All insulation materials and installation currently benefit from 0% VAT until at least March 2027, saving you 20% compared to the standard rate. Your energy supplier may also offer subsidised insulation through the ECO4 scheme.
Which Insulation Should You Do First?
If you are starting from scratch, the best order is usually: loft insulation first (cheapest, fastest payback), then cavity wall insulation (if your home has cavities), then draught proofing, and finally solid wall or floor insulation if applicable. This approach gives you the biggest savings for the least upfront cost.
Good insulation also makes your home ready for a heat pump, which works most efficiently in well-insulated properties. If you are considering the switch from gas, insulating first will lower your running costs and improve comfort.
Impact on Your EPC Rating
Insulation is one of the most effective ways to improve your Energy Performance Certificate (EPC) rating. Loft and cavity wall insulation alone can lift a property by one or two EPC bands. This matters for landlords (who must meet minimum EPC E for rental properties) and can add value when selling. See our guide on how to improve your EPC rating for more tips.
Frequently Asked Questions
How long does insulation last?
Most insulation lasts 40 years or more with no maintenance. Loft insulation may need topping up after 25 to 30 years if it has settled or been disturbed. Cavity wall insulation is designed to last the lifetime of the building.
Can insulation cause damp?
When installed correctly, insulation should not cause damp. In fact, it can help prevent condensation by keeping wall surfaces warmer. Problems only arise if the wrong insulation type is used for your wall construction, or if existing damp issues are not addressed first. Always use a certified installer.
Do I need planning permission?
Loft, cavity wall, and internal wall insulation do not normally require planning permission. External wall insulation may need permission, particularly in conservation areas or on listed buildings. Check with your local planning authority before proceeding with external insulation.
Is insulation worth it with a heat pump?
Absolutely. Heat pumps deliver heat at a lower flow temperature than gas boilers, so they perform best in well-insulated homes. Insulating before installing a heat pump means you can often choose a smaller, cheaper unit, and your running costs will be lower.