Skip to content
Need help? Call our Freephone 0800 260 5907

Solid wall insulation

What is it?

Solid walls have no gap in between them so they can’t be filled with cavity wall insulation. If your home’s is built before the 1920’s, it’s likely it will have solid walls.

To insulate a solid wall, you can install insulation on the inside of the outside of the building. This costs more that cavity wall insulation but it wall also save more money and energy.

Watch the below video to find out more.


There are two types of solid wall insulation:

Internal wall insulation:

Insulation can be applied to the internal walls of a property using rigid insulation boards or by building a stud wall and filling that with insulation material.

This method is generally cheaper than external wall insulation but it can come with some drawbacks including:

  • Reduced floor area of rooms with insulation
  • Installation can be disruptive
  • Can make it hard to fix heavy items to inside walls without special fixings

External wall insulation:

Insulation material can be fixed to the outside of a property which is then covered with render or cladding which can come in different styles such as smooth, textured, painted, tiled and panelled.

This method is generally more expensive but comes with additional benefits on top of keeping your home warmer such as:

  • Improving weather proofing
  • Protecting the brickwork of your property
  • Reduces draughts

However, this method may not be suitable for all properties and will require good access to outside walls, structurally sound walls and possibly planning permission.

What are the benefits?

Insulating the walls of your

property means less heat

can escape, lowering

the cost of heating

Using less energy to heat

your property means less

CO2 is released into the

atmosphere, reducing your

impact on climate change

Increasing the energy

efficiency of your property

increases the value of

the property and makes

it more appealing to

buyers and renters

A well insulated property

will be easier to heat to

a comfortable temperature.

It will also help keep the

property cooler in summer

What properties is it suitable for? 

Your home will be suitable for solid wall insulation if it meets the following criteria:

  • Its external walls have no gap
  • The masonry or brickwork of your property is in good condition.
  • There is good access to outside walls
  • No existing issues with damp

You will need an installer to carry out a survey to check that your house is suitable. If so, they will then be able to insulate your walls using mineral wool or polystyrene beads.

Click here to find out what insulation measures would be suitable for your property.


Typical cost

The cost of solid wall insulation will depend on the area of wall you’re insulating. However, the typical cost of insulating a 3-bedroom semi-detached house would be:

External wall insulation – £12,000

Internal wall insulation – £8,500

Available funding

Funding is available for owner-occupiers and privately let properties where occupiers meet certain eligibility criteria. Click the below tiles to find out if you’re eligible for funding.

How to find an installer

When choosing an installer, make sure they are Trust Mark accredited. This is a government backed accreditation that demonstrates installers are reliable and professional. This information can usually be found on an installers website. Click here to visit the TrustMark website to find an insulation installer near you.