The Installation Cost of Loft Insulation

All you need to know about installing loft insulation for your home including costs of materials, labour and time frames.

Loft Insulation Cost

What the job entails

One third of the heat in the average home escapes through the roof, which of course is reflected in the heating bill. With the current high energy prices, it's no surprise how popular loft insulation projects are with homeowners in the UK. But it's not just the lost heat, the increased stress on the boiler can often reduce the life expectancy so you have to replace the heating system more often. As loft insulation is pretty cheap, it's worth ensuring you have as much of it in the loft as you possibly can! This article assumes a standard pitched roof and a traditional cold loft type insulation (where you insulate immediately above the ceiling so little to no heat from your home gets into your loft space).

Laying loft insulation is an easy job to do DIY, but it is still better to use reputable loft installation companies as you can often benefit from energy grants that will reduce, or even eliminate the cost. You should check with local loft insulation companies in your area for information on available grants which are in place for homeowners to improve the energy efficiency in their homes. You should also check with your energy supplier(s) as they often run free energy efficiency programs which may include loft insulation works. If you are eligible for incentives, experienced loft insulation installers will have experience and know-how to help you connect with the various agencies to recoup the cost of the loft insulation.

If you do not qualify for a grant and have to pay for the loft insulation work yourself, then expect to pay in the region of £300 for a typical 3-bed semi-detached property. That price assumes no insulation currently fitted, but if you just need to “top-up” your current insulation (say from 100mm to 270mm), you can knock off £50-£75 from that price. Even paying for the insulation yourself still makes financial sense with a reasonably quick payback, plus it will improve the property energy performance certificate.

According to the Energy Saving Trust, you could save up to £250 a year simply by adding roof insulation to a currently uninsulated loft. In practice however, you will struggle to find a loft with no insulation at all, most will have some though usually much less than the recommended 270mm. It is worth noting that modern insulation is sold in depths of 100mm and 170mm, so if the current insulation in your loft is less than 100mm, it is likely to be old and should be disposed of. Older insulation types will not provide the same thermal performance as newer materials and the 170mm depth assumes modern materials. So do not simply lay new insulation on top of older materials.

If you are having loft insulation installed there are a number of additional jobs that could be carried out at the same time. For example any exposed pipes in the loft space should also be insulated, as should any water tanks. Whereas any electric cables in the loft should be left exposed so they remain cool. The loft hatch needs to insulated too and this is best done by attaching a block of polystyrene insulation to the upper (loft) side. If you are having the insulation professionally fitted then this is a good time to get the installers to check for any dampness in the loft space and discuss loft ventilation, dampness will severely reduce the thermal efficiency of the insulation so you should endeavour to remedy and damp issues before any insulation work is carried out.

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Cost of Installing Loft Insulation

The average material cost of loft insulation roll can vary from around £2-£5 per sq metre or more depending on the quality.

The average loft insulation specialist will usually charge around £150 to £200 per day and will usualy work independently to complete the job. The typical insulation specialist is expected to take around 2 to 4 hours to fully insulate your loft. It may take longer depending on the size of your loft and if you are looking to fully replace existing insulation.

Below are some estimated costs of hiring a specialist to install loft insulation:

Job Description Avg. Cost Duration
Installing new insulation where none is present £300-£350 2-4 hours
Topping up your current insulation £200-£250 2 hours

Cost Breakdown

Individual Costs of Topping up your Current Loft Insualtion - Total Cost: £250






Waste Removal


To simply meet current Building Regulations you need 270mm of mineral wool insulation. This is made up of 100mm in between the ceiling joists and then a further 170mm laid across the joists at 90 degrees to the bottom layer. But you should treat this as a minimum figure, not a target, more is definitely better!
This is a quick and mostly mess free job, allow around 2 hours for the average sized loft with straightforward access. Obviously any additional work being carried out at the same time, such as installing roof vents or a loft ladder will take longer.
Planning permission is not normally required for insulation as long as there is no change in the external appearance of the property. However, if the building is listed or in a conservation area, you should always check with your local planning authority. However, the insulation in your loft must meet the minimum energy efficiency values set out in the Building Regulations Approved Documents.
Just gently push a tape measure or ruler down the side of the loft insulation until it hits the plasterboard ceiling, then check the depth.
Yes, you will normally need to clear the loft before the insulation is installed. If you are unable to do this contact the installation company and discuss it with them, they may be able to do it for you for a small fee. But remember that after the additional insulation is laid across the joists, you will no longer be able to easily use the loft for storage.
Insulating loft boards called Space Board can be installed along with an 18mm chipboard deck to provide loft storage space with insulation. These polyfoam extruded polystyrene boards are designed to be placed on top of the ceiling joists instead of on top of the 170mm mineral wool insulation. but with 100mm of insulation installed between the joists, plus two layers of Space Board and a chipboard deck, you get the same thermal performance as if you had 270mm of mineral wool insulation, plus you get a usable loft space.