You can switch your energy provider for a better deal on your gas and electricity, but if your home is leaking heat, you’ll still be wasting money.
Improving home insulation makes your property more energy efficient and, after the cost of installation, you can save up to £400+ on your annual energy bill. By improving energy efficiency, you’ll also get a higher EPC rating and that can increase your home’s value.
What does insulation do?
Home insulation reduces heat loss on colder days and keeps you cool when the weather’s hot. It can also cut noise pollution from traffic and aircraft.
Sometimes only small fixes are needed to improve home insulation, like draught proofing or adding foil insulation behind your radiators. Other times, increasing energy efficiency is a bigger job.
What kinds of home insulation are there?
Different types of insulation suit different homes. Here are the most common:
- Cavity wall insulation fills the gaps between exterior and interior walls.
- Solid wall insulation adds insulation to the internal or external sides of solid walls.
- Loft and roof insulation fills spaces between the joists (the beams along the floor of your attic) or rafters.
- Floor insulation fits between floor joists, particularly effective for timber floors.
- Draught proofing seals gaps around doors, windows, chimneys, loft hatches and floors.
- Double glazing replaces single-glazed windows. Triple glazing is also an option.
Pipes, water tank and radiator insulation keeps water hotter for longer.
What types of insulation material are there?
Common home insulation materials include:
- Spray foam, a liquid chemical that expands into a foam.
- Batt insulation made of fibreglass, mineral wool (made from stone or glass) or cotton.
- Loose-fill insulation made from cork granules or cellulose such as plant fibres and recycled newspaper.
- Rigid foam insulation also known as high-density for boards or blown fibre boards. Made from polyurethane, polystyrene or polyiso.
- Reflective foil insulation made of aluminium.
Depending on the material, home insulation comes in rolls, boards or liquids. Prices vary depending on the one you choose. Some, such as fibreglass insulation, are more versatile than others.
Home insulation materials are given an R-value to indicate resistance to heat. The higher the R-value, the more effective the insulation.
If you’re a confident DIYer, you may be able to install home insulation yourself, but some require professional fitting using specialist equipment.
How does heat escape from a home?
Unfortunately, no matter how well-insulated your home might be, heat loss is inevitable.
The main ways that heat can escape are:
- Conduction - this is when heat moves through solid materials like metal or brick. Insulation works here by denying heat a path outside the home by using non-conductive materials to pack cavity walls and other spaces
- Convection - this is the natural tendency of warm air or water or other gases and liquids to rise, while cold air or water falls. Warm air has a propensity to escape through the loft or attic spaces if they are left uninsulated.
How much heat is being lost from different parts of my home?
If you’re in a flat, heat loss depends on the floor you’re on.
This is the typical heat loss in the average home:
- Walls - 30-40%
- Roof - 25%
- Windows - 18%
- Doors - 15%
- Floors - 10-20%
The U-value shows how much heat (in Watts) is lost per square metre of a roof, wall or floor for every degree difference (K) in temperature on each side of the surface. For example a solid brick wall typically loses 2W per (m²K).
Current building regulations require minimum U-values. For external walls this is 0.18 W/(m²K), making insulation essential.
How much does insulation cost?
Home insulation rates vary depending on the type of insulation you use and the kind of property you have - and also whether you fit it yourself.
Here are some estimated values of home insulation costs from the Energy Saving Trust, based on getting a professional in to do the job.
- Cavity wall insulation (whole property) - up to £4,300, including redecoration.
- Solid wall insulation: external wall insulation (whole property) - around £11,000.
- Solid wall insulation: internal wall insulation (whole property) - around £7,500
- Uninsulated loft - up to £1,100 (to comply with recommended 270mm depth).
- Topping up existing loft insulation - up to £850.
- Floor insulation - £4,700 or more for solid floor insulation.
How can I save money on home insulation?
Cheaper home insulation options are available - for example adding thicker curtains around windows or buying a hot water cylinder jacket (from around £30). For more quick and easy ideas to increase your home’s energy efficiency, read 100+ energy-saving tips for your home.
To save money, you could add home insulation when you’re having other building or decorating work done. Or, if you’re financially able, increasing your mortgage can also cover the cost of expensive home insulation upgrades.
If you’re planning a home insulation upgrade, you should also think about how long it will take to get your money back through energy savings.
For big insulation investments it also matters how long you plan to live in the property, as well as what you’ll be adding to the sale value.
How much can I save if I get insulation?
Again, the amount you can save depends on the type of home you have and the insulation measure you’re installing.
According to the Energy Saving Trust, cavity wall insulation can save between £125 and £455 a year on your energy bills (depending on your home), and loft insulation can save between £225 and £415 a year.
Can I get any insulation grants?
Home insulation rates can be high, but grants and financial help are available.
- Energy Company Obligation (ECO) scheme (latest version ECO4) - could be an option if you receive certain benefits or you’re a core group customer from scheme year 12 onwards under the Warm Home Discount Scheme. Under this scheme, some suppliers offer free insulation or grants to help make your home more energy-efficient.
- The Great British Insulation Scheme is expected to run until March 2026. It allows a wider group of people (those in properties with a low-rated EPC and certain council tax bands) to apply.
Do I need planning permission for insulation work?
In most cases, you don’t need planning permission for home insulation. But there are some exceptions:
- If you’re adding external wall insulation
- If you have a listed building
- If you live in a conservation area
Even if you don't need planning permission, certain building regulations may still apply. Always check with your local council before starting any home insulation projects.
