How to buy wall insulation Wall insulation FAQs

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Insulating your home's walls can be a cost-effective energy-saving measure

How much will it cost to get wall insulation installed?

The cost of insulating your property's walls depends on the size of your home, whether the walls are cavity or solid and the condition they're in.

You’ll find a guide to the approximate costs and savings involved in installing the different types of wall insulation on our cavity wall insulation and solid wall insulation pages.

Installing wall insulation is one of the most cost-effective improvements you can make to your home. The savings you make on your heating bills means insulation could pay for itself in as little as nine months.

energy-bill

Ask your energy supplier about discounts on insulation

Can I get financial help for paying for wall insulation?

Yes. The government’s Carbon Emissions Reduction Target (Cert) programme obliges the large energy providers to meet carbon saving targets by, for example, promoting energy efficiency measures such as free or discounted insulation.  

If you are aged 70 or more, or receive certain benefits, you could even get loft and cavity wall insulation installed completely free of charge. Some councils also offer discounts and free insulation for 'priority' groups. Offers change all the time and can be location specific so, before carrying out any wall insulation work, check whether an energy grant or special offer is available. 

There is less financial help available for solid wall insulation, but many councils now offer grants and/or council tax rebates for energy efficiency home improvements. Contact your council's energy efficiency officer to find out what is available in your area.

The Energy Saving Trust's grants and offers database will help you to find contact details for local schemes – or you can call your local EST advice centre on 0800 512 012.

Our full guide to energy grants has more information on which grants are available and how to apply. 

How do I know which type of walls my property has?

cavity wall graphic

If your home was built from 1920 onwards, it's likely to have cavity walls. The cavity should be at least 50mm wide and the walls need to be in good condition to be suitable for cavity wall insulation. 

If your house was built in the past 10 years, it's likely that the cavity walls have already been insulated.

The graphic opposite shows the difference between cavity walls and solid walls. The pattern of the bricks can often be an indication of the type of wall you might have. 

How do I know if my property is suitable for cavity wall insulation?

Most homes with cavity walls are suitable for cavity wall insulation as long as:

  • the cavities aren't blocked in any way (for instance with debris or rubble)
  • the cavity is at least 50mm wide (you can measure the width of the wall in a window or doorway)
  • the external brickwork/ masonry is in good condition
  • the house is not susceptible to damp and/or in a location exposed to high levels of wind-driven rain.

To find out whether your house might be in a risk zone for high levels of wind-driven rain, check our map and advice in our damp problems page.  

As wall cavities catch rain coming through the outer wall, could wall insulation become damp?

Provided the insulation material is installed correctly and is water-repellent, damp shouldn't be an issue.

Any installer registered with the CIGA should check whether your home is suitable. Their work and materials will be covered by a 25-year guarantee.

However, some cavity walls – for example those regularly exposed to wind-driven rain – are not suitable for cavity wall insulation. In early 2011 Which? uncovered some bad practices when it came to getting advice about cavity wall insulation for a house prone to damp problems. Watch our undercover video together with some information and advice about damp risks.

double-glazing

Installing double glazing is another energy-saving measure

Do I need planning permission for wall insulation?

Planning permission is not normally required for wall insulation.

However, if your property is listed, is in a conservation area or the insulation will change the appearance of your property, you should consult your local planning authority.

How do I find a wall insulation installer?

You can contact the Energy Saving Trust (EST) for a list of recommended insulation installers by calling 0800 512 012.

For cavity wall insulation, choose an installer registered with one of the following organisations:

  • The National Insulation Association (NIA)
  • The Cavity Insulation Guarantee Agency (CIGA)
  • The British Board of Agrément (BBA).

Check that your installer has signed up to a code of professional practice, such as that offered by the NIA. Also ask if the insulation installation is guaranteed for 25 years by the Cavity Insulation Guarantee Agency (CIGA).

The CIGA provides independent 25-year guarantees for cavity wall insulation fitted by registered installers in the UK and Channel Islands.

What other types of insulation could help me save money on my heating bills?

You can buy jackets to fit around your hot water cylinder and piping, which are available from DIY stores and can be fitted yourself, provided that your pipes are easily accessible.

The energy savings are much smaller than with wall or loft insulation but, as jackets cost between £5 and £15, they pay for themselves in a year or less.

You can also reduce the amount of heat lost in your home by fitting draught excluders for doors, windows and letterboxes opening on to the outside. Gaps between skirting boards and floorboards are also worth tackling.

Double glazing also cuts heat loss and also reduces noise and condensation problems. You can expect savings of around £165 a year on bills if you replace whole-house single glazing with Energy Saving Recommended double glazing. Remember to close your curtains at dusk to stop heat escaping. 

To reduce your fuel bills further, make sure you're on the right energy tariff. Find the cheapest possible deal on your gas and electricity supply using our energy price comparison site Which? Switch.

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