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Cavity Wall Insulation

If your property was constructed after 1930, it is probable that it has Cavity Walls, which are walls made up of two masonry walls with a minimum gap of 40mm between them. These walls can be identified by their brick pattern, called ‘stretcher bond,’ where all bricks are laid lengthways. Alternatively, their thickness, typically over 270mm, can also help identify them.

To insulate Cavity Walls, bonded polystyrene beads are injected by drilling a series of holes in the mortar joints of the external wall. Once the cavity is filled, the holes are made good and colour-matched as closely as possible to the original mortar. The insulation installation comes with a 20-year insurance-backed guarantee.

Cavity Wall Insulation can improve your energy performance certificate’s rating and save you money on heating bills, up to £150 per year, as well as providing better warmth during colder months. A Cavity Wall is one of the two walls required for Cavity Walls, which are walls built next to each other with a small gap of around 50mm between them.

If your home was constructed after the 1920s, it is probable that it has cavity walls. These walls consist of two separate layers with a space in between, known as the cavity. The outer layer is often made of brick, while the inner layer can be made of brick or concrete block. Metal ties connect the two walls together (refer to both images). For homes built before 1920, solid walls are more common. Solid walls have no cavity and consist of a single, solid wall, typically constructed from brick or stone. Please see Internal Wall Insulation for information regarding these types of walls.

Cavity wall insulation is a clever way to keep your home warmer and reduce your energy bills. It involves filling the gap between the walls of your house with insulating material, which helps to prevent heat from escaping. This means you can enjoy a cosier home without worrying about wasting energy or money.

  • More than one-third of the heat lost in an uninsulated home escapes through the walls.
  • Insulation saves you up to £275 per year on your energy bills.
  • Insulation helps keep your home warmer by preventing heat from escaping through the external walls.
  • Insulation helps reduce your carbon footprint by using less energy to heat your home.
  • Insulation is the number one recommendation on an Energy Performance Certificate (EPC) to improve energy efficiency.

To insulate your home’s cavity walls, the process usually takes about 2-3 hours, but it could take longer depending on your home’s size and accessibility. During the installation, the installer will drill small holes, about the size of a 10p coin, into the outside wall of your home and inject insulation into the wall cavity using special equipment. This process is done in a specific pattern to ensure complete coverage. Once the insulation is injected, the holes are filled with mortar to match the colour and texture of your home’s exterior. If your home has a pebbledash finish, pebbles are added to match the existing texture. After the installation, the holes are difficult to see, and your home will be more energy-efficient!