Internal Wall Insulation (IWI) Grants

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What is Internal Wall Insulation?

Internal Wall Insulation, or IWI, creates warmer, more energy efficient homes by adding a layer of insulation to the internal walls. IWI can be added to buildings of any age, and it’s usually much cheaper to install than external wall insulation.

And if you qualify for the Government’s ECO4 scheme, an internal wall insulation grant could cover the full cost of your installation. You’ll find out more about that below.

How Does It Work?

Internal wall insulation creates a thermal barrier that traps warm air in a room and helps to prevent it escaping. There are a few ways of installing IWI. Fixing rigid insulation board or insulated plasterboard to your existing interior walls are perhaps the simplest and most space saving options, but you can also create stud walls against existing surfaces and add a layer of insulation within each.

Internal wall insulation does take space. Each wall will be around 100mm thicker, but it’s a trade off that could create a much warmer home that’s cheaper to heat.

The Benefits of Internal Wall Insulation

Cut Energy Bills

Figures vary by home and the type of IWI you choose to install, but installing internal wall insulation can be powerfully effective. You’ll see quoted savings of between £400 and £700 per year for a detached house, but it’s difficult to reach an exact figure when every home is different and prices are changing so rapidly. We’d suggest working on the basis that installing IWI throughout your home will cut around 35% off your annual energy bill.

Enhanced Comfort

Most UK homes have a problem with heat transfer. Heat moves from warm areas to colder areas. The greater the difference (such as in winter), the faster the transfer. That’s why, even when your heating is on high, your home can still feel cold (particularly around your feet), because the heat is escaping through the walls and roof. IWI is like wrapping each room in an insulating blanket. It helps stop heat escaping. And that makes every room feel so much cosier, even on the coldest days.

Quieter Home

Frustrated by noisy neighbours, the sounds from the street or even just the kids gaming in the next room? IWI insulates sound as well as heat, so your home becomes a more relaxing place to be.


Once your insulation has been installed, you can decorate over it just as you would with any wall. That means your home can look exactly as you want it, with no intrusive visual impact (or the sort you might get if you installed external wall insulation).

Better Energy Efficiency

It’s not just money you save when you choose IWI. Because you use less energy, you cut the carbon footprint of your home. Studies suggest that over the life of your home, each square metre of insulation could cut a tonne of CO2e (carbon dioxide equivalent) from your emissions.


If you’re a private tenant, a homeowner or a landlord*, you might be able to get a grant for your internal wall insulation under the Government’s ECO4 scheme.

The scheme offers funding to a wide range of customers, and we can help you secure funding for IWI and other heating and insulation upgrades.

Then, our expert team will install your IWI.

*Sorry, we can’t accept applications from social housing customers.


Quality People, Quality Materials: We’ve been helping people create warmer, more efficient homes for years. We only use materials that are guaranteed to deliver long-lasting results. And we only use skilled, experienced professionals to complete each project.

Custom Solutions: Every building is unique. We’ll assess your home and find the best insulation solution for you.

Clear, Simple, Transparent: Before you make any decisions, we’ll give you a clear understanding of your options, the potential energy and financial savings, and we’ll help you secure any funding grants that you’re entitled to.

Do you qualify for funding?

Use our interactive form to see if you qualify for internal wall insulation grant funding.