In the current climate of raising costs of energy prices and overall living costs increasing with the highest rate of inflation for forty years we are all looking for ways to reduce those heating bills.

Strange as it may seem but spending money can actually sometimes save you money in the long run and never more so than on your uninsulated home. And the simplest and most efficient way to insulate a loft space is easier than you would imagine.

Energy efficiency is not just improved carbon footprint and better for the environment but for your wallet too. Insulating your home and especially your cold loft will help to reduce energy bills whilst lowering your carbon emissions, but how can we achieve this without breaking the bank?

Can You Do-It-Yourself?

With certain types of insulation materials, installing your own insulation is definitely doable and not subject to building regulations. And you can save money not hiring a professional installer. Installing loft insulation boards and fibreglass is a simple DIY project. Other insulation types, such as spray foam insulation, require the use of a professional.

All insulation material is easy to purchase and affordable and with the right guidance easy to install. Follow our helpful how to guides for easy installation.

See Insulation types

Should Loft Insulation Be Installed Between Joists?

Insulating between the joists of your loft floor will keep your house warmer but make the roof space above colder. This means pipes and water tanks in the loft space could likely freeze, so you will need to insulate them too. If you need a warm loft for living space or storage, you will need roof insulation too.

Should I Remove Old Loft Insulation Before Laying New?

You can lay new insulation over old insulation as long as it isn’t wet. Removing your old insulation isn’t necessary and leaving it can be quite beneficial. This is because most insulation will retain its thermal properties, so leaving it in place will mean that you continue to benefit from it whilst also having an additional layer of insulation on top!

What Is The Best Type Of Loft Insulation?

Three main types of insulations are recommended for insulating your loft, and all three have good to excellent energy ratings. Here we have the three most commonly used in the UK.

Fibre Loft Insulation

Fibreglass Classic and efficient loft insulation
Classic and efficient loft insulation

Glass wool, or fibreglass as it is commonly known, has been used for insulation since the late 1930s and is the most common form used in the UK as it offers good thermal and sound insulation for those living in a semi detached house with noisy neighbours.

This comes in large rolls which is easy to transport and store. The method of laying fibreglass insulation is the easiest of the three types on offer as you can cut fibreglass loft insulation rolls and batts using a sharp utility knife.

As fibreglass can dull blades quickly, using a disposable knife with swappable blades may be a better choice. You’ll need to lay the insulation over a solid board, to ensure that it can be firmly cut to size.

The current recommended depth for loft insulation is 270mm (10.5 inches). If your insulation is less than 150mm (6 inches), then it is worth considering getting it topped up for better thermal efficiency.

Sheet Insulation Boards

Insulation boards are easy to install and efficient way to insulate a loft
Insulation boards are easy to install

Firm boards of either synthetic or natural materials are a fantastic solution for insulating your loft, as they can be used for the floor space and the roof. The boards provide highly effective insulation for your loft space and can also be decorated over. The downside is that sheet insulation tends to be the most expensive type.

Although more expensive than rolls, they offer good thermal values at half the thickness. Also, you can easily store items directly on top of them. They can be cut to size using a saw to fit snugly between joists or rafters, while holes can be drilled around light fittings.

Current government recommendations are for loft insulation to achieve a depth of between 250mm and 270mm, but some new properties are increasing their level of loft insulation to 300mm. Again, if the loft has adequate ventilation, this is fine.

Spray Foam

Spray foam is still used despite some minor problems
Spray foam is still used despite some minor problems

Spray polyurethane foam insulation is the most energy-efficient insulation to create an air barrier in the attic. Certain spray foams can expand up to 100 times its original size, filling all the nooks and crannies in the attic.

It is the type of insulation that is most cost-efficient as it reduces energy bills more than the other two options despite the expense of the installation.

However, spray foam insulation has been used without incident in many homes for over thirty years, though there have been reported problems, including reducing ventilation within a roof space, causing condensation, stopping moisture from escaping, and potentially placing roof timbers at risk of decay.

This is definitely not a do-it-yourself project, as the equipment needed is highly specialised.


Does Loft Insulation Need An Air Gap?

Leave a gap of at least 25mm around the loft’s edge for ventilation. Do not lay the insulation all the way up to the eaves. If your boiler flue goes through the attic, also leave a gap around this.

Can You Lay Insulation Over Electrical Wires?

Yes, loft insulation can be laid over wires, most attic insulation, such as Rockwool or fibreglass, is naturally fireproof, but you should consult an electrician to make sure because too much insulation can affect the current carrying capacity of the wire.

Will Insulating My Loft Stop Condensation?

Foam boards and insulation rolls/batts are effective at decreasing the amount of condensation in your loft space. This is due to the fact that they reduce conductive heat loss through the structural elements of your roof.

Is The Government Offering Grants For Loft Insulation?

Loft insulation grants can be 100% fully funded, so homeowners will not have to pay anything. However, depending on the eligibility criteria of your property, you may be asked to make a contribution towards the cost, and in some cases, this can be up to 25% of the total cost of installation.


Whether you do-it-yourself or hire a professional, there are efficient way to insulate a loft. The end result is going to be a much better insulated home and therefore lower energy bills. Add to that the energy rating of your house will improve which is beneficial if you decide to sell.

Lowering costs and being more sustainable in how we live is the key to running an efficient home for us and future generations.