The prices in this guide are accurate, as of 2023
Properly insulating your loft can make your home more energy efficient, helping you cut your heating bills. Insulation pays you back in the long run and is relatively cheap to install. It’s no surprise that adding insulation is one of the most popular eco home improvements, as it can also add value to your home.
If you’re trying to save money (and keep your house as warm as possible) then the right insulation can do both these things. If you’re converting your loft, or building an extension, then proper loft insulation is also a building regulation.
On average, your loft insulation could cost you between £920 and £2,320, depending on how big your loft is. This guide covers a range of loft insulation methods for several different properties, as well as other considerations you might want to make. There are also some useful tips if you want to DIY your loft insulation.
The standard thickness recommended by the government for loft insulation is 270mm. Cost of labour also rises in London and the South East. The prices in this guide include the cost of materials and installation. They also include VAT.
Is insulating your attic energy efficient?
An uninsulated home can lose a quarter of its heat, just from the roof. With a 40-year lifetime, correctly installed loft insulation will pay you back several times over by reducing your energy bills every year.
This is how much you could save on a yearly basis, by properly insulating your loft:
|Detached home||Semi-detached home||Mid-terrace home||Bungalow|
|Turning an uninsulated loft into a 270mm insulated loft||£580||£255||£230||£365|
|Turning a 120 mm insulated loft into a 270 mm insulated loft||£40||£25||£20||£35|
Properly insulating your loft will also save thousands of kg in CO2 emissions, helping you reduce your carbon footprint.
Which loft insulation is best?
The type of insulation you get will depend on how easy it is to access your loft, and whether you want to install your insulation yourself or hire a professional. Different insulations use different materials, so it’s also worth considering how eco-friendly you want to be.
|Insulation material||What is it?||Pros||Cons||Can you DIY ?|
|Loose-fill insulation||Loose material like cellulose fibre or wool which are placed evenly around the loft. Often used to top up existing insulation.||Good for filling irregular loft spaces and gaps between joists
Good for areas that are harder to access
Light, easy to handle
|May require a professional to install it
Not suitable for draughty lofts (can be dislodged)
|Yes, for a confident DIYer|
|Blanket insulation||Made from mineral fibre, glass, rocks, or felt, this is one of the most common types of loft insulation.||Easy to install (can be DIY)
Cheapest type of loft insulation
There are some more eco-friendly options like recycled glass
|Some materials used in blanket insulation are skin irritants
Reduce the space in loft (head height)
Bulky and doesn’t fit in all areas of loft
If not installed properly, it’s liable to tearing
|Sheet loft insulation||Insulated boards that are built to insulate the sloping sides of your loft. These fit across loft joists.||Good for lofts which have limited head space
Very effective (high value per unit thickness)
More expensive than most other options
Can’t be used on structural elements
|Yes, for a confident DIYer|
|Spray foam insulation||A layer of foam is sprayed from a special machine over the areas that need insulating.||Eco-friendly
Can improve structural strength of home
Good for hard to access areas of loft
Highest R-values (the higher the R-value, the greater the insulating effectiveness)
|More expensive than most other options
Require specialist installation
Made from polyurethane which contains toxic compounds
Messy to install / leaks through unsealed joints
How long does it take to install loft insulation?
Most loft insulation installations take under a day and can be completed within a couple of hours. Blanket installations take less time than sheet installations, but you can expect labour costs to be about the same, especially if you’re paying a daily labour rate.
It will take longer than this to install insulation if you’re doing it yourself.
How much does it cost to insulate a loft?
Looking at average installation costs for an entire loft, you could pay around:
The bigger your loft, the more it will cost to insulate, especially if you end up having to pay for additional services, such as rewiring electrics. The type of insulation you get will also affect costs. The above examples include the cost of blanket loft roll insulation.
To find out the prices for different insulation types, let us know what you have in mind by speaking to a skilled tradesperson today.
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Can I insulate my loft myself?
If you do want to install insulation yourself, then the above costs will give you a sense of how much materials will set you back. Though some types of insulation can be installed DIY, professionally installed insulation lasts longer, and is generally more effective.
Since insulation is installed primarily to be as cost-saving as possible, we recommend you hire a professional, unless you are confident you can insulate your loft properly yourself.
If you do want to do it yourself, you should keep a few things in mind:
- Make sure the wiring in your loft is kept above the insulation. If your wires are getting stretched because of your new insulation, then you should hire an electrician to reroute them.
- You should clean your loft and clear it of any stuff that is being stored there before you begin insulating, regardless of whether you want to DIY or hire a loft insulation installer.
- Don’t forget about your pipes and tanks. These will need to be insulated as well to prevent them from freezing.
- If you want to use your loft as a storage space, then you’ll need to lay boards over your joists. If you want to convert your loft into a room, you’ll need to hire professionals to do this.
- Don’t use less than the recommended amount of insulation. The government recommends insulation of 270mm thickness. Using a thinner size will cost you money in the long run, because your less efficient insulation will raise your energy bills.
- Make sure you don’t cover any vents whilst you lay down your insulation. Your loft needs to be properly ventilated to avoid damp from developing. If there aren’t enough vents in your loft, you may need to have additional ones installed. If you do have a lot of damp problems, then we recommend you don’t opt to DIY, as you’ll need a professional to help fix this before your insulation is installed.
- To calculate how much insulation you’re going to need, you need to know the floor area of your loft (length x width), and the depth of insulation you already have. Knowing the joist heights in your loft is also a good idea, so that you can know whether to lay the first layer of insulation between joists. Don’t worry about your old insulation, you can lay new insulation over it (just make sure you’re not squashing it down).
Using 100 mm thick insulation rolls with a 8.3 m2 coverage, you can calculate how many rolls you’ll need by doing: Area (in sq m) x (1 – 0.1) ÷ 8.3 sq m. This is the equation you need for laying a base layer (25mm or less of existing insulation). If you want to add a top layer over an existing layer of insulation (for instance 100mm), the equation would be: Area (in sq m) ÷ 6.47 sq m (using 170mm rolls with a 6.47 m2 coverage).
DIY loft insulation installation will save you from having to hire an installer but might mean your loft will be less energy-efficient than it could be.
Loft insulation labour costs
If, on the other hand, you want to hire someone to insulate your loft for you, so that you can ensure everything is done correctly and you maximise the heat retention in your home, then you can do so here.
The average loft insulation costs around £450 and £1,200 (labour costs only) for the entire project. How much you end up spending depends on the scope of your project, and where you live in the UK.
Labour costs rise in London and the South East, sometimes by as much as 20% more on average.
- It costs about £5 – £8 per metre to insulate pipework (materials and installation)
- It costs about £150 to insulate a water cistern held in your loft
- You may also need to relocate electrical wires during the insulation. An electrician will charge around £250 a day to do this
- A loft ladder and hatch will cost around £350 (materials and installation) for an existing opening. You’ll have to factor in another £250 if you’re looking to build a new opening to your loft
- If you need new loft legs (stilts), it will cost around £600 for an average loft, using chipboard. This will take roughly a day to do
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A properly insulated loft can considerably reduce your energy bills, helping to make your home more eco-friendly by lowering your carbon footprint as well.
How much you end up spending will depend on the type of insulation you decide to get, and where you live in the UK, as cost of labour rises in London and the South East. The size of your loft will also impact on costs.
To get a more accurate sense of how much you could pay for loft insulation, we recommend you ask for multiple quotes before you settle on a price. You can hire a skilled insulator here.