Summary: How much does it cost to insulate a loft, average loft insulation installation cost and average price for loft insulation.
If your home has no insulation, about a quarter of all your heat is lost through the roof. It makes sense therefore to consider putting insulation in your loft to provide an easy and effective solution to reducing your energy loss, making your home warmer and therefore reducing your heating bills. With energy bills increasing all the time there never has been a better time to look at insulating your loft, saving energy and saving money. Using less energy also reduces your C02 emissions, a contributing gas to climate change. With the UK government having a continued commitment to energy efficiency; insulating your home is likely to stay high on the agenda for some time.
Average Cost
| Job | Average Cost | Updated | Quote |
| Loft insulation (Materials only) (m²) | £3 – £5 (m²) | 2019 | n/a |
| Loft insulation (Installation & materials) | £200 – £500 | 2019 | n/a |
Factors to consider
Providing you have a dry loft, free from condensation and damp, then you can go ahead with your loft insulation project. You will also need reasonable, safe access to the loft to enable the work to be carried out – a loft hatch of approximately 60cm x 60cm will be adequate. If you live in rented property it is essential you get the permission of the landlord before installing any loft insulation.
There are 4 main types of insulation to choose from:
Blanket insulation
This type of insulation comes ready prepared in rolls (often referred to as quilts), usually of 3 or 4 inch depth. There are a large variety of width and lengths available making it simple to find a roll which suits your loft. The roll is designed to fit tightly between the joists making a secure coverage. There are different types of insulation including foil-backed felt, mineral wool, glass fibre or rock fibre. The recommended depth for mineral wool insulation is 270mm.
Loose fill insulation
In older properties, the joists are often shallower; this restricts the depth you can fill with loose fill insulation. Fillings can be mineral wool, cellulose fibre, cork granules or exfoliated vermiculite. Whilst the material can blow about in draughty lofts, this type of insulation is great where the joists are not regularly spaced or where obstacles such as pipes make laying insulation blanket tricky.
Sheet insulation
When you are going to use the loft space for storage or a room space, the best insulation to use is thin sheets of mineral fibre of fibre glass on the slope of the roof rather than the floor to keep the heat of that space inside that space. You may find that attic rooms are very hot in summer and very cold in the winter. Good insulation should balance this out. It is essential that ventilation is factored into the wall, as well as ensuring fire prevention. Newer loft conversions may already have some insulation in them, but as the regulation changed in 2003, it is worth checking any pre-existing insulation.
Blown fibre insulation
This type of insulation must be installed by a properly trained installer and must not be attempted as a DIY job. Fibrous matter is blown in-between the joists by the professional installer using a hose and takes only a few hours. If your loft is draughty then this material can blow about in the wind, making the process inefficient; you may want to consider other methods, if this is the case with your loft. Mineral fibre and rock fibre are also damp and rot proof and resistant to vermin.
If you are doing the job yourself and once you have purchased all the items you need, you should give yourself approximately half a day to lay your loft insulation. Correctly installed your new loft insulation should have a life span of around 40 years – an investment well worth making. However don’t assume that when it is done, you can sit back and relax, with constantly improving energy efficiency targets, the government recommendations for the thickness of insulation may increase, meaning that you may need to add further insulation as a later date.
Flat roofs also create a different situation, recommended to be done by professionals; insulation can be fitted externally underneath the waterproof membrane, ideally done when this waterproof covering needs its regular replacement.
Costs to consider
There are many grants and special offers available to help with installation of loft insulation. Everybody in the UK is entitled to some kind of subsidy as the UK Government is obliged to reduce its Carbon Dioxide emission significantly. Searching on the internet will provide many databases of resources to help you save money. It goes without saying that paying an installer will incur higher costs than doing the job yourself. But it’s fair to say that if you currently have no loft insulation and you install some yourself you will easily make your costs back within a couple of years in energy savings alone.