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Home & garden.

1 July 2021

Solid wall insulation FAQs

We answer your questions about solid wall insulation. Find out what you need to know about internal and external wall insulation.
Which?Editorial team
External solid wall insulation 450381

Find the answers to your solid wall insulation questions:

What type of walls does my property have?

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 home was built in the past 20 years, it's likely that the cavity walls have already been insulated.

If your home is more than 100 years old, it's likely to have solid walls. That means you'll need solid-wall insulation to stop heat from escaping.

Can I get financial help for solid wall insulation?

There is little financial help available for solid wall insulation. Contact your council's energy-efficiency officer to find out if something might be available in your area. Certain households might qualify for the Energy Company Obligation.

Do I need planning permission for solid wall insulation?

Planning permission is not normally required for wall insulation.

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

Where can I find a solid wall insulation installer?

Make sure you choose an installer registered with one of the following organisations:

  • The National Insulation Association (NIA)
  • The British Board of Agrément (BBA).

Also check that your installer has signed up to a code of conduct, such as the NIA's Code of Professional Practice. 

To find a local, trustworthy installer, go to Which? Trusted Traders

You can also contact Simple Energy Advice with any questions by calling 0800 444202.

What other types of insulation are available?

Insulating your loft is cheap and could save you up to £215 a year.

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 smaller than with wall or loft insulation but, as jackets cost around £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 up to £115 a year on bills if you replace whole-house single glazing with 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. Use our independent switching site, Which? Switch, to compare gas and electricity prices.