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Keeping the heat in

Installing insulation is one of the best ways to keep the heat in your home and the cold out – helping you to save money on your energy bills and make your home cosier over the winter months.

Insulating your home (keeping the heat in and the cold out) is one of the best ways to save money on your energy bills.

There are lots of ways to insulate. From quick DIY fixes to bigger jobs that require a professional, here’s everything you need to know about stopping heat loss and staying warm at home.

Double and triple glazing

Did you know that making your windows more energy efficient by improving the glazing can reduce your energy bills and help you enjoy a warmer home for less?

Double and triple glazing are both types of energy efficient window glazing. The term is used to describe windows with two or more panes of glass in a sealed window unit.

Energy efficient glazing can be expensive to install, so if you’ve got a smaller budget, you can also make improvements by installing secondary glazing, or even just by using heavy curtains.

What are the benefits of double and triple glazing?

Double or triple glazed windows help to reduce heat loss through windows, meaning you’ll have fewer draughts or cold spots around your home.

They’re also good at soundproofing your home – blocking out noisy traffic or people on the street. Another benefit is that they can help reduce the amount of condensation that builds up inside windows, protecting you from damp and reducing the risk of mould.

How much does double glazing cost?

There are several different styles and materials that can be used for double and triple glazed windows, so the cost will vary depending on the type you choose.

Windows made from PVC are cheaper than frames made from hardwood, for example. Always get three quotes to compare costs.

How do you choose double or triple glazed windows?

Windows use an energy efficiency rating scheme to help you choose the most efficient windows for your budget. They’re rated on a scale from A++ to E, with A++ being the most efficient.

Both the frame and glass are assessed, to account for heat loss, draughts and the effect of sunlight, giving you a rating that tells you the overall impact of installing that particular window in your home.

How do you install double or triple glazed windows?

Most houses are allowed to replace single glazed windows with double or triple glazed ones, however you should check with your local planning office if you live in a listed building, in a conservation area, or have an ‘article four direction’ on your property (this removes the right of permitted development).

It’s likely you’d need to use a professional to fit double or triple glazing. We recommend using an installer who is a member of the Glass and Glazing Federation – search their website to find a member who works in your area.


The doors in your home can also be insulated or draught-proofed to prevent heat from escaping.

If you’re considering installing a new door, you’ll need to get approval from the relevant building control body.

Most new external doors (ie any door that connects to the outside) now come with insulation as standard, which will help reduce heat loss.

If you’re not ready to invest in a new door, you can improve the energy efficiency of existing doors by fitting draught-proofing strips at the bottom and around the sides. You could also consider buying and fitting a keyhole cover and letterbox flap.

See also: draught proofing

Wall insulation

If you want to make a real difference to your home, installing wall insulation is a great way to save energy and cut costs off your heating bill.

This is because around a third of the heat lost from an uninsulated home escapes through the walls – so it’s a good place to start improving your home’s energy efficiency.

Are there different types of wall insulation?

Most homes will either have cavity walls or solid walls, so the first thing you’ll need to do is work out your wall type.

If your house was built after the 1920s, it probably has cavity walls. A cavity wall is made up of two walls with a gap in between, known as the cavity, which can be filled with insulation.

Older houses built before 1920 are more likely to have solid walls. These walls don’t have a cavity, but they can still be insulated either from the inside or outside of the property.

How much does wall insulation cost?

Costs for installing wall insulation vary significantly, depending on the type of insulation you need and the size of your home.

For a semi-detached home, cavity wall insulation would typically cost you around £1,200. If you have solid walls, the installation costs are significantly higher – between £10,000-£14,000 for a semi.

How much could you save on your energy bills?

How much you save on your energy bills will also vary, but for cavity wall insulation, you should be able to make back the installation costs in five years or less, regardless of your house size.

Installing cavity wall insulation in a semi-detached, gas-heated house could save you around £285 a year on your energy bills. For solid wall insulation in the same type of property, the savings are higher – at £390 a year.

How do you install wall insulation?

If you have cavity walls, you’ll need to employ a registered installer to fill the cavity with insulation – it’s not a job you can do yourself.

A specialist will drill holes in your outside wall, inject insulation into them, and then seal them with cement. They should be able to complete the job in around two hours.

Installing solid wall insulation is a bigger job and one that you should hire a specialist company for. If you want to try and keep costs down, it’s worth installing insulation when you’re having other building or decorating work done – for example, if you’re getting a new bathroom or kitchen fitted.

Your installer should be a member of the National Insulation Association – check their website to find verified insulation companies. You should also check that the insulation is covered by an appropriate 25-year guarantee.

See also: finding an installer

Loft and roof insulation

We all know that hot air rises, so one of the most important places to stop heat escaping from your home is through the roof.

With around a quarter of heat lost through the roof, insulating your loft, attic or roof is an effective way to reduce heat loss and save money on your energy bills.

How do you install loft insulation?

If your loft is easy to access, does not have damp problems and you don’t have a flat roof, you can probably insulate it yourself.

Use rolls of insulation to lay down two layers. The first is laid between the joists and the second is laid at right angles on top of the first layer, to cover the joists and increase the thickness of the insulation. There are a variety of materials out there for DIY loft insulation.

If you have damp problems or require more complex insulation, you should use a professional installer, as they will need to assess the damp before carrying out any work. Similarly, if you have a flat roof, you should always use a professional.

Use the National Insulation Association website to find an accredited loft insulation installer near you.

How much does loft insulation cost?

The cost of installing loft insulation varies slightly, depending on the size of your house and the level of insulation you want to fit.

In a semi-detached house, insulating an uninsulated loft with 270mm of insulation will cost you around £530 – but it should save you £255 a year on your energy bills, so you’ll make back the installation cost in just over two years.

If you already have some loft insulation (up to 120mm) and want to top it up (to 270mm), it should cost you around £425 for a semi-detached house. It’ll save you an extra £25 a year on your heating costs.

Floor insulation

Insulating your ground floor is another great way to keep the heat in and the cold out.

If you’re looking for a quick fix, rugs and carpets on the floor will help your feet feel warmer, which might mean you don’t need to put the heating on as much – saving you money on your bills.

If you live in an upper or mid floor flat, you don’t usually need to insulate your floor as heat will rise up from properties below, giving you a bit of extra warmth for free.

How do you insulate your floor?

Most homes with either have a solid concrete floor or a suspended wooden floor.

Solid concrete floors, which are often found in newer properties, can be insulated by adding a layer of rigid insulation board on top.

Wooden floors are more likely to be found in older homes – you can often work out if you have timber floors by checking for air or ventilation bricks on the outside wall of your home. It’s important to ensure you don’t block these bricks, as they are needed for ventilation and can help prevent damp.

You can insulate wooden floors by lifting the floorboards and laying down mineral wool insulation between the joists. You might need to support the insulation with netting fixed between the wooden joists.

If you don’t feel confident insulating the floor yourself, look for an installer who is a member of the National Insulation Association.

How much does floor insulation cost?

Costs vary depending on the type of floor and size of your home. We estimate you’d need to spend between £1,300 and £2,700 to insulate a suspended wooden floor, while solid floor insulation could cost a lot more.

You could save around £75 a year by insulating under the floorboards in semi-detached house, or up to £130 if you live in a detached property. The comfort factor is worth considering too – as well as saving on your bills you should also notice a difference underfoot if your floors were very cold before.