How to insulate a loft and reduce energy bills

If your loft isn’t insulated, your home will lose a quarter of its heat through the roof. Find out how to insulate your loft and lower your energy bills.

In an uninsulated home, approximately 25% of the heat escapes via the roof. As such, getting loft insulation installed is a no-brainer to save on your energy bills. It’ll  also help with your energy performance certificate (EPC) rating.

Another way to ensure money isn’t escaping from your home is to do an energy comparison to find the best gas and electricity deal for you.

Here we look at what help is available for getting loft insulation installed, and – if you fancy getting your hands dirty – how to do it yourself.

What help is available for installing insulation?

If you’re wondering how much it costs to insulate a loft, the good news for some is that several energy suppliers run schemes offering to provide services such as loft insulation free of charge for those that need help with energy bills.

This offer is part of the Energy Company Obligations (ECO) scheme, which is run by Ofgem, and aims to tackle fuel poverty and carbon emissions. The scheme obliges energy companies to provide free energy-saving services to customers on specific benefits.

You may be eligible if you claim any of the following:

  • Child Benefit
  • Income-related Employment and Support Allowance (ESA)
  • Income-based Jobseeker’s Allowance (JSA)
  • Income Support
  • Tax Credits (Child Tax Credits and Working Tax Credits)
  • Universal Credit
  • Housing benefit
  • Pension Guarantee Credit
  • Pension credit saving credit

It’s worth noting that the scheme doesn’t only provide loft insulation. Rather, properties are inspected to find what actions can be taken or products retrofitted to save energy usage.

The scheme is available to people who own their own home. But if you rent from a social housing provider, there’s a good chance they’re involved in similar schemes, so it’s worth contacting them to find out.

You can see which companies are signed up to the scheme on the Ofgem website, including contact details. Also, if you’re struggling to pay, there may be help available with your energy bills – including hardship grants for those with energy debt.

What is the Great British Insulation Scheme?

Another government scheme aiming to save households money on their energy bills includes the Great British Insulation Scheme. This offers part or fully subsidised insulation to households with an energy performance certificate (EPC) rating of D or below, in the following council tax bands:

  • A-D in England
  • A-E in Scotland and Wales

Check which council tax band your property falls under.

Again, this scheme doesn’t only provide loft insulation, but also other types of home insulation depending on the property’s requirements.

How much does loft insulation cost?

If you don’t qualify for any of these schemes, then according to the Energy Saving Trust, getting loft insulation installed will cost roughly £880 for an average mid-terrace, or £930 for a semi-detached house. This is to install the recommended minimum of 270mm of insulation in a previously uninsulated loft.

It should be possible to recoup the cost fairly quickly, however. The Energy Saving Trust estimates you should save around £225 on your annual bills if you live in a mid-terrace, or £250 if you live in a semi – based on the 1 October energy price cap. You’ll also save 550 kgCO2 and 620 kgCO2 on your emissions respectively.

Plus new loft insulation lasts for around 40 years, so you won’t have to worry about replacing it anytime soon.

Can I insulate my loft myself?

If you plan to put insulation between the joists in your attic, the job should be reasonably straightforward, provided the attic is in reasonably good condition and free from damp.

The joists are the horizontal beams which run along the floor of your loft:

New roof loft insulation between joists

It’s probably a good idea to call in a professional if any of the following apply:

  • You’re not confident with what you’re doing
  • There’s damp in the attic
  • Insulation needs to go between your rafters – the angled beams supporting your roof

Getting it professionally installed will often be the safer and more efficient option. It’ll also guarantee the most heat retention if the job’s professionally done, so should pay for itself over a few years.

Getting a professional to insulate your loft

If you’ve decided that laying insulation yourself isn’t your bag, then it’s worth finding a professional via the National Insulation Association (NIA). All members are vetted and conform to a code of practice. Find an NIA installer near you

Alternatively, if you live in Scotland, get in touch with Home Energy Scotland.

I’m up for giving it a try

If you’re willing to give it a go, here are the steps to take. It should go without saying that safety should be paramount when you’re in the attic. Never put your weight on any part of the floor which is unboarded, as you don’t want to plunge through the ceiling. Instead, it’s best to get around the attic using crawl boards – boards which are big enough to span three joists.

In terms of safety equipment, you’ll need:

  • Safety goggles
  • Facemask to prevent from breathing in dust and insulation material
  • Safety gloves
  • Crawl boards

For the job, you’ll need:

  • A roll of roof insulation (Wickes recommends glass mineral wool material insulation), which cost about £150 a roll
  • Cold water tank jacket
  • Pipe insulation
  • Duct tape
  • Downlight protectors if you have recessed lights

You’ll also need tools such as:

  • Tape measure
  • Saw for cutting the insulation roll
  • Retractable knife for finer insulation cutting
  • Metal knife or straight edge

Step #1: clear the attic

First of all, clear out your attic. This isn’t the kind of job you can do around all your possessions and accumulated clutter. Emptying the loft will expose all the joists. Don’t bring the roll of insulation up just yet.

At this stage, identify anything used for ventilation, such as vents, airbricks or grilles. You’ll want to make sure you don’t block these, so that air can still circulate freely around the attic.

Step #1B: using the attic for storage

Please note: If you still want to store items in your loft, you’ll have to lay boards elevated over the insulation – effectively creating a second floor. You shouldn’t place items directly on the insulation, or cram it in by nailing boards, as compressing the insulation will stop it doing its job properly.

Instead, you can get timber battens or purpose-built plastic legs which fit on the joists. These will support your new floor. If you or a tradesperson do this, be sure to leave a slight gap between the insulation and the underside of the floor, so that moisture doesn’t get trapped.

Step #2: lag your water pipes and tanks

When the insulation is in place, the loft will be much colder, as less heat will be making its way into the loft from downstairs. For this reason, you should lag any water pipes and tanks in the attic. This will help prevent them getting too cold.

Installing water pipe insulation.

Measure your water tank so you know how big a tank jacket to buy. Measure your water pipes, and cut pipe insulation to size with a sharp knife. After wrapping the pipe insulation around your pipes, you can secure it in place with duct tape.

Step #3: check your wiring

Insulation shouldn’t be laid on top of electric wires or cables, as this creates a fire risk.

If you need to move things around, turn the electricity off at the mains before handling wires. Lift them out before laying insulation underneath. You can tidy them up by clipping them to the rafters using cable clips. Again, if you’re worried about what to do with your wiring, don’t be shy about seeking professional advice.

Now’s also the time to put downlight protectors over any lights, if required.

Step #4: measure your insulation

Measure the loft and make sure you have enough insulating material to cover the whole of the surface up to a depth of at least 270mm.

Measure the joists in your loft. They’re generally around 100mm high, and your first layer of insulation should be as thick as the joists are high – give or take no more than 25mm.

There may already be insulation between the joists which you’re topping up. Measure the width of the insulation, ensuring that the combined width will be between 270 – 300mm.

Step #5: unroll your insulation

Now bring up your roll of insulation. Measure the width between the joists so you know how wide to cut it. This will usually be 400mm or 600mm. Cut the roll to this width using a hand saw, or even a long serrated kitchen knife.

It’s best to approach laying the insulation outside-in, so lay your crawl boards at the furthest edge, then work your way inwards. You want to leave a gap of about 25mm between the eaves and the insulation, as there should be an air gap for ventilation. Maintain this distance on both sides of the attic.

Unroll the insulation running lengthways between the joists, making sure it fits snugly. It’s best to work backwards so you’re not putting your weight on it. When starting on a new length of insulation, push the end up snugly to the previous length.

On reaching a cross-beam, using a metal ruler to keep the edge straight, trim the end of the roll with scissors or retractable knife. Again, ideally it should fit snugly.

When you’ve filled the space between the joists in this direction, lay a second layer of insulation at right angles to the first. This sits on top of the original layer and the joists.

The blanket you use this time should be 200mm thick, bringing the total thickness of insulation in your loft up to 300mm, which is enough to stop warm air escaping from your house.

Step #6: insulate the loft hatch

It makes sense for the hatch to be insulated too, to stop heat escaping through the entrance. You can cut a piece of insulation to size – again making sure it’s at least 270mm thick – and secure it to the hatch using a cut piece of insulation as a ‘jacket’. You can fix this to the hatch using tacks or by stapling it in place. You might also want to draught-proof the edges if there are gaps.

To see the process in action, watch this how to install loft insulation YouTube video, produced by Homebase and Silverline Tools.

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