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Internal wall insulation

Improve the comfort and efficiency of your home - perfect for solid wall properties.

Award Winning Installer    |    Trustmark Approved    |    All-in-One Energy Experts    |    Nationwide Coverage

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The smartest way to insulate solid wall homes.

If your home was built before the 1920s, it likely has solid walls — which means it could be losing a huge amount of heat. Internal wall insulation (IWI) is one of the most effective ways to tackle this, helping to dramatically cut heat loss and reduce energy bills.

Unlike cavity wall insulation, which fills a gap between two layers of brick, IWI is applied to the inside of your external walls. It creates a thermal barrier between your home and the cold outside air — without changing how your property looks from the outside.

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What is internal wall insulation?

Internal wall insulation involves fixing a layer of rigid insulation board or insulated stud framing to the inside of your external walls. The surface is then plastered and decorated as usual, leaving a neat, warm, and energy-efficient finish.

Key benefits:

  • Helps reduce energy bills by preventing heat loss
  • Makes rooms feel warmer, faster
  • Keeps the external appearance of your property unchanged
  • Can help reduce condensation and damp
  • Often included in fully funded ECO4 or GBIS upgrades
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Is internal wall insulation right for my home?

This type of insulation is ideal if:

  • Your home has solid walls with no cavity
  • You want to preserve the external look of your property
  • External wall insulation isn’t possible (e.g. due to planning rules)
  • You're happy to make small adjustments inside (e.g. moving radiators or sockets)

We’ll carry out a full property survey to confirm if IWI is the right solution. If it’s not suitable, we’ll recommend an alternative — such as external wall or loft insulation.

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Can I get loft or roof insulation for free?

Yes. Both loft and roof insulation are commonly funded measures under both ECO4 and GBIS.

You could be eligible for full funding if:

  • You receive certain means-tested benefits
  • Your income is below £31,000 or have a long term medical condition
  • Your home has an EPC rating of D, E, F, or G
  • You live in a Council Tax band A–D (or A–E in Scotland/Wales)

Not sure where you stand? We’ll check for you.

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Explore Insulation

Discover our most popular guides, packed with practical advice and clear information to help you save energy, reduce costs, and make informed decisions.

GBIS GUIDES

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GBIS APPLY

Our insulation guides

Information on all the types of insulation we fit for our customers.

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GBIS ELIGIBLE

Am I eligible for GBIS?

Find out if you meet the GBIS criteria for free home upgrades

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