Loft insulation

You can insulate your loft without losing it as a storage space.  

Insulating a loft will create either a ‘warm loft’ or a ‘cold loft’.  

With a warm loft, no changes are made to the floor. This means you can carry on using the loft as a storage space just the same as before. 

You can still use a cold loft for storage, but first you’ll need to raise the loft floor above the level of the insulation. Doing so makes sure that the  flooring boards don’t squash the insulation. It’s important to avoid this, as squashing insulation reduces its effectiveness. It can also lead to condensation problems.

The recommended level of loft insulation is 270mm. If your loft currently has less insulation than this, you can make savings and feel warmer by topping it up. If your insulation is old, it may not be keeping the heat in properly. Replacing the old insulation can save you money and keep you warmer.   

Your Energy Performance Certificate (EPC) should show the level of your loft insulation. If you live in Scotland, then you can search for your EPC on the Scottish EPC register website. If you live in England, Wales or Northern Ireland, then you can search for your EPC on the gov.uk website.

According to the Energy Saving Trust, insulating the loft of a mid-terrace house costs around £560. This price is based on a professional installer insulating the loft with 270 mm of mineral wool.  

The cost of insulating your loft will vary depending on the size of the loft and what materials you use. Whatever the initial cost, the savings on your energy bills mean the work should pay for itself within two years. Loft insulation has an average life of 40 years, so it’s an incredibly cost-effective addition to your home.  

If you’re confident with DIY, you may be able to cut costs further by doing the job yourself. 

Loft insulation grants are available through our Home Energy Scotland service. The grant usually covers the full cost, so you should be able to get free loft insulation. You can find out more in our Loft insulation grant section below.

These are rigid insulation boards, cut to the appropriate size. You install them between the rafters (beams) of the roof.   

Remember: Insulating in this way means that you don’t have to raise the level of the floor before boarding it.

Warm loft insulation means that heat won’t be lost through your roof, but it does now have other escape routes. You’ll need to insulate any walls you share with your neighbours (party walls), plus walls which lead outside (gable walls).

You spray foam insulation between the rafters (beams) of the roof.  As with sheet insulation, you’ll have to insulate the walls in your loft to make sure the warmth can’t escape through them.

This is the kind of insulation that comes to mind for most people when they think about insulating a loft. It comes in big rolls which you unroll and lay between the floor joists of the loft. You then add a second layer is across the joists, at a 90 degree angle to the first layer.   

If you are comfortable accessing your loft space, you can fit blanket loft insulation yourself. As it’s usually made from rock, glass, or mineral fibre, you’ll need protective gloves, goggles, and a dust mask.  

For a more environmentally friendly option, you could choose insulation made from sheep’s wool.

As you may have guessed, you buy this type of insulation ‘loose’. Depending on the material used, it looks a lot like gravel, and you spread it in a similar way. You pour the insulation between the floor joists and rake it to ensure an even level.   

Loose fill loft insulation is convenient for insulating hard-to-reach sections of your loft. If the shape of your loft makes it tricky to insulate with blanket insulation, then you may want to use loose fill insulation.

It’s possible to get loose fill insulation that’s made from recycled materials, such as newspaper.

A potential downside to loose fill insulation is, of course, that it’s loose. This means that it might blow around your loft on particularly windy days.

As with cavity wall insulation, material is blown in using a hose. This can be especially useful for lofts which are difficult to access.  

Blown fibre loft insulation uses a variety of materials, including fibreglass and cellulose.   

This is a professional job – you would need a certified installer to carry it out.

If you have downlights, you will need to take some fire safety precautions. The heat produced by lightbulbs poses a fire risk if it comes into contact with insulation. In order to protect against this, you can buy downlight covers. These fit over the body of the downlight so the light itself isn’t touching the insulation.

Don’t forget to insulate the loft hatch, as this will prevent both draughts and heat loss.   

It’s possible to buy insulated loft hatches, but if you’re on a budget, there are also DIY options.  

A simple method is to fill a plastic bag with insulation material, tape it shut, then glue it to the loft-side of the hatch. If the hatch has a hinge or a ladder attached, then make sure that the bag doesn’t interfere with any of the mechanisms.    

You can also cut an insulation board to the correct size and shape, then attach this to the hatch. Again, make sure the board doesn’t stop the mechanism from working.  

Once you’ve insulated the hatch, you’ll also want to draughtproof around the edges. You can use adhesive draughtproofing strips. Cut these to size and stick them around the edges of the hatch.

If you are creating a cold loft, the lower temperature could make any pre-existing damp problems worse. If loft insulation is your next DIY project, it’s a good idea to speak to a professional about ventilation.