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How to Buy Loft Insulation

Loft Insulation Costs and Savings

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Loft Insulation Costs and Savings

How much money can you save if you install loft insulation? We'll help you weigh up the costs and savings of installing loft insulation in your home.

Installing loft insulation could slash your energy bills by up to £225 a year. How much you can save will depend on your home. Keep reading to find out more.

We’ve worked out how much you can save on your energy bills and how long loft insulation will take to pay for itself. 

This payback time is very quick if you didn’t have any loft insulation before. But our calculations have worked out you can still save by increasing the amount of loft insulation you have.

As well as loft insulation prices and savings, we also explain the types of loft insulation - and we reveal the best free and cheap insulation deals.

Loft insulation costs and savings

Professionally installed loft insulation for a typical three-bedroom, semi-detached house with gas central heating costs around £300. It will take around two years to pay for itself through the savings you’ll make on your heating bills if you go from no insulation to the recommended amount.

The recommended thickness for loft insulation is 270mm. The first thing to do is check whether you have any insulation at all in your loft and, if you do, how much. If you already have some insulation in your loft but it falls short of the recommended 270mm, then you could make further savings on your energy bills by topping it up.

In the tables below, which are separated according to whether you’re insulating from scratch or just topping up, you can see how much it costs to install loft insulation. Plus how much you'll save per year in money and CO2, and how quickly you’ll make your cash back in bill savings. 

Of course, it’s much cheaper to buy the insulation and fit it yourself - by doing that you’d greatly reduce your payback time. Loft insulation typically costs around £20 for a 100mm roll designed to cover 8.3m².

Loft insulation (0-270mm)
Type of property Installation cost Savings per year CO2 savings per year (kg) Payback time
Detached house (four bedrooms) £395 £215 950 1-2 years
Semi-detached house (three bedrooms) £300 £130 560 2-4 years
Mid-terrace house (three bedrooms) £285 £115 500 2-3 years
Detached bungalow (two bedrooms) £375 £185 820 1-2 years

Table notes: figures based on a typical gas-heated home in England, Scotland and Wales. All data obtained from the Energy Saving Trust (EST).

Loft insulation (120-270mm)
Type of property Installation cost Savings per year CO2 savings per year (kg) Payback time
Detached house (four bedrooms) £290 £20 90 14-15 years
Semi-detached house (three bedrooms) £240 £10 50 24 years
Mid-terrace house (three bedrooms) £230 £10 50 23 years
Detached bungalow (two bedrooms) £280 £15 70 18-19 years

Table notes: figures based on a typical gas-heated home in England, Scotland and Wales. All data obtained from the Energy Saving Trust (EST).

Some energy suppliers still offer free insulation to householders who fit certain criteria (such as being a member of a vulnerable group or those who receive certain benefits). 

Check which free offers are available in our guide to free insulation.

Loft or roof insulation?

Lofts are usually cheaper and easier to insulate than roofs. But if your loft is being used as a living space, you would have to insulate the roof. 

We’ll show you the different options available - go to roof insulation.

Fitting loft insulation

One reason some people don’t insulate their loft is because they want it for storage - the new minimum 270mm required thickness of insulation would go over the joists, making it impossible to lay boards on top. 

But there is a way around this, enabling you to both have 270mm of insulation and use your loft for storage:

  • Insulate between the joists with mineral wool and then lay rigid insulation boards on top, with wooden boarding on top of that. You can buy insulation board prebonded to floor boarding to make the job easier.
  • You could also raise the level of the floor so you can fit enough mineral wool beneath the new floor level. 

Either way, make sure you don’t squash the mineral wool when you fit the boards on top. If you do, this will reduce its insulation properties. 

Improve your home's energy-efficiency rating

The energy performance certificate (EPC) you get when you buy a home shows an overall energy-efficiency rating for your home from A (the most energy efficient) to G (the worst). It also contains advice on how to cut carbon emissions and fuel bills by making home improvements.

If you’re selling a property in England or Wales, you must get an EPC. You’ll also need one if you’re a landlord looking to market a property for rent - like buyers, prospective tenants can ask to view this before they sign a rental contract.

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Fitting insulation is an effective way of raising your home’s energy-efficiency rating. If your home isn’t insulated, the EPC will recommend the type and level of insulation required for maximum efficiency.

If you do have loft insulation but it’s deemed to be old, inadequate or inefficient, the EPC may also recommend necessary improvements.

A quick way to cut your energy bills is to use our independent switching site, Which? Switch, to check you're on the cheapest energy deal.