The ultimate guide to home insulation: costs, savings and benefits

Insulation is a great way to make your home warmer and reduce your heating bills. Find out more with our complete guide to insulating your home.

Insulating your home is one of the best steps you can take to reduce heat loss. And as we move into winter, improving your insulation could cut your heating bills, save you money, and help reduce your home’s carbon emissions. 

Here’s a complete run-down of the steps you can take to insulate different parts of your home and enjoy better energy-efficiency. 

What is home insulation, and why’s it important?

If a building’s not insulated, as much as half of its heat can escape through the roof, walls, windows and floor. Poor insulation makes a home hard to keep warm, and more expensive to heat. That’s because when left unchecked, heat will naturally flow from warmer to cooler spaces until there’s no temperature difference. 

In a typical home, your walls lose the most heat – as much as 30% to 40%. Your roof is next, losing around 25%, followed by windows and doors at around 15-20%. Your floor can lose around 10%.¹

But when you insulate, it’s like throwing a big, cosy blanket around your home. And that helps it to more easily maintain the temperature you set on your thermostat. 

How heat escapes from your home

Heat can escape from your home in a few different ways:

• Conduction – this is when heat moves through solid surfaces such as metal or brick.
• Radiation – this carries heat directly from warm objects to cooler objects. In your home, heat radiation is often lost through the wall behind a radiator if that wall isn’t insulated.
• Convection – this happens when warm air rises. In an uninsulated wall space, air picks up heat from the warm side of the wall and circulates it to the cold side.
• Air movement – draughts are another common form of heat loss. That’s because they take warm air from within the home and move it outside (while also replacing it with cold air coming in). 

The benefits of home insulation

• A well-insulated home reduces heat loss in cold weather – and it can even help to keep a home cool in hot temperatures. All of which makes for a much more pleasant and comfortable home, whatever the weather.
• Insulation is also a brilliant way to reduce noise pollution. If you live near a busy road or under a flight path, insulation will help to minimise medium-to-high-frequency noise from outside. 
• Insulating our homes is better for the planet too. When we use less energy, we burn less fuel, which stops unnecessary carbon from being released into the atmosphere. 

5 steps to insulating your home

As the diagram below shows, there are five main areas to focus on when it comes to properly insulating your house. Let’s go through them one by one:

1. Loft and roof insulation

You can lose up to 25% of your home’s heat through an uninsulated roof.² You likely already have some – but adding an extra layer to existing insulation can still help to lower your heating bills and reduce your carbon footprint.

Read more about all the benefits in our ultimate guide to roof and loft insulation.

2. Cavity wall insulation

Whether yours are cavity or solid walls, insulating them properly will help keep heat in. The type of walls you have depends very much on when your house was built. As a rough guide, solid wall constructions are often pre-1919, while uninsulated cavity walls are usually found in brick and block buildings built between 1920 and 1975. Most built after that will also have cavity walls.

If you can stop heat escaping through your cavity walls, you’ll reduce heat loss by as much as 40% – making this a potentially highly cost-effective way to retain heat in your home and save money on your bills. 

Find out more in our guide to cavity wall insulation.

3. Solid wall insulation

Did you know that solid walls let twice as much heat escape as cavity walls? For a detached house, insulating solid walls could save you as much as £550 a year.³

Our guide to solid wall insulation has more!

4. Underfloor insulation

If your home has a particularly draughty floor, you could first try some quick fixes, such as plugging any holes, filling gap-ridden skirting boards or adding a couple of rugs. But if you’re planning on changing the floor anyway, laying new carpet, or renovating downstairs, this could be a great time to add some insulation. Doing that alone could reduce heat loss in your home by 10%.

Find out more about the pros and cons of underfloor heating in our practical guide.

5. Energy-efficient windows and doors

You could be losing 15-20% of your home’s heat through your windows and doors. Double or even triple glazing will help reduce heat loss dramatically. And even if you don’t want to fully replace your existing windows and doors, there are a few clever fixes you can do to help.

Find out more in our complete guide to energy-efficient windows and doors.

The best home insulation materials

Sheep’s wool, paper, foil, polystyrene and polyurethane spray foam – good insulators come in various forms. Most work by trapping tiny pockets of air within them – and the most commonly used are mineral and glass wools, which come in a roll, as a blanket, or as a type of batt or slab.

How much can home insulation help you save on bills?

Insulation costs can vary depending on what you’re having done. Much of what you can do could pay for itself within 2 to 5 years. One of the cheapest ways to reduce heat loss is by draught-proofing – and payback is fast with this one, so it makes even more sense if you’re renting.

Plus, home insulation can do more than just help you save money on energy. With the UK committed to reach net zero emissions by 2050 (relative to 1990 levels), home insulation can play a big role. That’s because the energy used in UK homes makes up about 20% of our greenhouse gas emissions – and three-quarters of that comes from heating and hot water alone.

With better home insulation key to lowering carbon emissions, it’s clear that retro-fitting existing homes with better insulation can help support our efforts to lower our carbon footprint.

Make your home more cosy with financial support from the Great British Insulation Scheme

The UK government recently announced the launch of the Great British Insulation Scheme. It’s part of their effort to help reduce carbon emissions and help cut energy bills.

Through the scheme, you could access support to insulate your home with cavity wall or loft insulation. If you’re eligible, you could get this at a reduced price or completely free.

Find out more about the Great British Insulation Scheme and check if you’re eligible. 

Home insulation work and planning permission

Most of the time, you won’t need planning permission before carrying out insulation work. But if you’re doing external wall insulation, or if you’re planning glazing work in areas where there are conservation schemes, you should check with your local council’s building control department first.

Even when you don’t need planning permission, other building regulations could still apply. So it’s always a good idea to check. 

Sources and references

¹ https://www.uswitch.com/insulation/guides/home-insulation/

² https://energysavingtrust.org.uk/advice/roof-and-loft-insulation/

³ https://energysavingtrust.org.uk/advice/solid-wall-insulation/ Savings accurate as of November 2024.