Close this search box.
September 22, 2023

What is Cavity Wall Insulation?

Cavity wall insulation is a method of insulating the gap or “cavity” between the inner and outer walls of a building. This cavity, typically around 2-4 inches wide, was initially designed to prevent moisture from seeping into the inner walls. However, with the growing emphasis on energy efficiency, this empty space is now being utilised to prevent heat from escaping the building.

Cavity wall insulation works by filling the gap between the walls with insulating materials. This layer of home insulation prevents heat transfer through the walls, keeping the indoor environment warmer during the cold months and cooler during the hot months. By reducing the need for excessive heating or cooling, cavity wall insulation lowers energy consumption and, consequently, reduces heating bills.

How Can I Tell if I Have a Cavity Wall?

If your home was constructed after the 1920s or within the last 40 years, chances are high that you have a cavity wall. To confirm this, you have a couple of options. One is to request a home energy survey, which can provide definitive information about the construction of your walls.

Alternatively, you can perform a visual inspection. Simply examine the brick pattern, if the bricks have a consistent pattern and mortar joints are regularly spaced, you likely have a cavity wall.

  • Your home was constructed after the 1920s
  • Your home was built within the last 40 years
  • If the walls are more than 260mm thick
  • If the wall features bricks with a consistent pattern and mortar joints that are regularly spaced

How is Cavity Wall Insulation Installed?

Cavity wall insulation installation generally takes around a day or two for an average-sized home. The process involves creating small holes, typically about 25mm in diameter (similar to the size of a ten pence-piece), in the mortar between bricks at regular intervals. Through these holes, the insulation material is injected into the cavity. After the insulation is in place, the holes are sealed.

In certain situations where walls are hard to reach, our installers use telescopic lance systems. For new-build properties, rigid insulation boards are often integrated into the wall cavities during the construction phase.

Cavity Wall Cost & Savings

Cavity wall insulation costs vary based on factors like property size and the walls to be insulated. Factors such as the area covered and insulation material type also affect the final cost. However, the investment is worthwhile, with potential savings of up to £680 annually on energy bills for a 3-bedroom house. This insulation not only promotes sustainability but also provides a clear economic advantage.

Cavity wall insulation significantly contributes to enhanced energy efficiency and financial savings. By March 2022 energy savings had reached 224,400 GWh, with cavity wall insulation contributing a huge 43% towards these savings.

With financial incentives and grants available, such as the Eco Scheme and the Great British Insulation Scheme, the cost of implementing cavity wall insulation becomes even more appealing.

Is Cavity Wall Insulation Right For Your Home?

Determining if cavity wall insulation is suitable for your home involves considering various factors.

  • If your house was built in the last 20 years, your walls might already be insulated. Our registered installers can clarify this through a home energy survey, assessing your wall’s composition.
  • Contact your local authority’s building control department for additional insight.
  • If your home meets specific criteria such as unfilled cavity walls, a cavity width of at least 50mm, and well-maintained masonry, standard cavity wall insulation could be a viable option.
  • If your home has narrow or uneven cavities, it might require polyurethane foam insulation, which, while pricier, is highly effective.
  • Address any damp problems before proceeding with insulation.
  • If your walls are shared with neighbours, a cavity barrier might be necessary to contain the insulation.
  • If you reside in a flat, obtaining a collective agreement for insulating the entire block is typically needed.

To make an informed decision tailored to your home’s specifics, consulting with specialists in insulation and damp prevention is advised.

What is the Life Expectancy of Cavity Wall Insulation?

Cavity wall insulation has a life expectancy of 25 to 40 years, depending on various factors such as the quality of the installation, the materials used, the local climate, and maintenance practices.

Properly installed and maintained insulation can effectively improve energy efficiency and comfort in a building for several decades. However, over time, factors like settling, moisture intrusion, and deterioration of insulation materials might reduce its effectiveness, necessitating potential replacements or updates. Regular inspections and addressing issues promptly can help prolong the life of cavity wall insulation.

What Happens to Cavity Wall Insulation Over Time?

Over time, cavity wall insulation’s durability can be affected by factors like external wall quality and building location. While moisture entering the cavity is a consideration, proper installation and maintenance can prevent potential issues like interior damp patches.

The insulation’s longevity is tied to these factors, and measures to prevent moisture entry are crucial for maintaining its effectiveness and overall performance.

Does Cavity Wall Cause Damp?

Cavity wall insulation is a beneficial energy-saving solution when installed correctly. While concerns about dampness may arise if not properly managed, these issues can be avoided by ensuring proper installation practices.

Installing cavity trays between the layers and maintaining consistent insulation without air gaps are essential steps to prevent heat loss, condensation, and associated dampness. By adhering to these guidelines, cavity wall insulation can effectively enhance energy efficiency without causing damp problems, offering long-term benefits for homeowners.

What Houses Should Not Have Cavity Wall Insulation?

Cavity wall insulation may not be suitable for houses with the following.

  • System-built properties.
  • Homes with elevations that are exposed to wind-driven rain
  • Timber and steel-framed properties
  • Houses that have rainwater systems in poor condition or guttering that is not lined.

Rest assured, one of our professional installers will carry out a survey to check that your property is suitable for cavity wall installation free of charge.

Is Filling Cavity Wall Insulation a Good Idea?

Understanding cavity wall insulation and how it works is crucial for making informed decisions about enhancing your home’s energy efficiency and comfort. Cavity wall insulation serves as a remarkable solution to minimise heat loss, reduce energy consumption, and create a more thermally balanced living space.

By filling the gap between the inner and outer walls with insulating material, this technique forms a barrier that impedes heat transfer and maintains indoor temperatures.

Let's calculate how much you can save

Justine Effective
Read more articles...