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Cavity Wall Insulation

cavity wall

Up to a third of the heat lost from your home will escape through the walls. Not so if you have cavity wall insulation. If you do have cavity walls and haven’t yet put a coat in between them, read on to discover the benefits of cavity wall insulation.

What are cavity walls?

Cavity walls consist of two walls with a gap (cavity) in between. The outermost wall is usually made of brick, while the innermost wall is constructed of brick or concrete block. The two walls are held together with metal wall ties. 

If your house was built after the 1920s, then you probably have cavity walls as opposed to solid walls which are a feature of much older buildings. Nowadays, many new energy-efficient properties will have cavity walls that have been pre-filled with insulation material.

How does cavity wall insulation work?

A Cavity Insulation Guarantee Agency-qualified professional can insulate your cavity walls by drilling holes into the outer wall and filling the cavity (gap) with insulation materials. Once your cavities are filled, your walls will prevent heat transfer in your walls, and therefore, help keep heat indoors.

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What are the types of cavity wall insulation?

The most common cavity wall insulations in the UK use: 

  • Blown mineral fibre or wool - your installer will do this by heating and spinning the insulating material to create a fibrous material which is then blown into the cavity.
  • Polystyrene pellets (granules or beads) - the chosen pellets are pumped into the cavity along with an adhesive. Once inside, the two materials form a solid bond that prevents heat transfer.
  • Urea-formaldehyde foam - after pumping the foam into the cavity, it expands, becoming firm within a couple of minutes. Your installer should return in a week to seal the walls after the foam has hardened.

Cavity wall insulation cost

If you haven’t yet filled your cavity walls, the good news is, it’s one of the cheapest energy-saving measures you can install in your home. According to the Energy Saving Trust, cavity wall insulation costs between £300 and £750, depending on the size of your property. With an average saving of £245, the cost of the insulating your cavity walls should pay for itself in one to three years.

Can I get free cavity wall insulation?

Yes. If you receive certain benefits, you might be able to get a government grant for insulation to help with some, or all, of the cost of insulating your cavity walls. 

How long does cavity wall insulation take?

Cavity wall insulation usually takes between 6-12 hours to complete, and there should be no need to vacate the property while the work takes place.

Benefits of cavity wall insulation.

As well as the previously mentioned benefits, other advantages of cavity wall insulation include:

For more energy-saving tips, have a look at our guide on how to make your home warmer.

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