What is a cavity wall?

A cavity wall is a type of wall construction that consists of two parallel layers or leaves of masonry separated by a gap or cavity in between. Each layer, known as a leaf, is typically made of brick, concrete blocks, or stone, and the cavity between them is left empty or filled with insulation material.

The outer leaf of a cavity wall is usually the more decorative and weather-resistant layer, while the inner leaf provides structural support and serves as a barrier between the interior and exterior of the building. The gap or cavity between the leaves is typically around 50-100mm wide.

Cavity walls have been widely used in construction since the late 19th century, primarily for their ability to provide improved insulation and resistance to moisture. The gap between the leaves helps to prevent the transfer of heat, reducing energy loss and improving thermal efficiency. It also allows any moisture that penetrates the outer leaf to drain down the cavity and away from the inner leaf, preventing dampness and potential damage to the structure.

Cavity walls are commonly found in residential and commercial buildings and have become a standard construction method in many regions. The use of cavity walls has increased over time due to advancements in insulation materials and techniques, leading to improved energy efficiency and overall building performance.

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. Many homes, especially those built after the 1920s, have an empty space between the outer and inner walls, which can be filled with insulation material to improve energy efficiency and thermal performance.

The insulation material used in cavity wall insulation helps to reduce heat loss from the building, keeping it warmer in cold weather and cooler in hot weather. It creates a barrier that prevents the transfer of heat through the walls, reducing the need for excessive heating or cooling and consequently lowering energy bills.

The most common insulation materials used for cavity wall insulation are mineral wool, foam, or beads made of polystyrene or polyurethane. These materials are typically injected into the cavity through small holes drilled in the outer walls. Once installed, they fill the cavity, providing an additional layer of insulation.

It’s important to note that not all homes are suitable for cavity wall insulation. Factors such as

the construction of the building, the presence of existing insulation or dampness issues, and the

type of cavity walls determine whether cavity wall insulation is appropriate.

Benefits of cavity wall insulation

Cavity wall insulation offers several benefits for buildings and homeowners. Here are some key advantages of cavity wall insulation:

1. Energy Efficiency: One of the primary benefits of cavity wall insulation is improved energy efficiency. By filling the gap between the inner and outer walls with insulation material, heat loss through the walls is significantly reduced. This means that the building can retain heat better during cold weather and remain cooler during hot weather. As a result, less energy is required for heating or cooling, leading to lower energy consumption and reduced utility bills.

2. Cost Savings: Lower energy consumption translates into cost savings for homeowners. With cavity wall insulation, the amount of heat generated inside the building is better retained, reducing the need for continuous heating or cooling. This can result in significant long-term savings on energy bills.

3. Increased Comfort: Cavity wall insulation helps to create a more comfortable indoor environment. By reducing heat loss, it prevents cold spots near external walls and minimizes drafts, making the living spaces more pleasant and evenly heated. Additionally, cavity wall insulation can also help to reduce noise transmission from outside, resulting in a quieter interior.

4. Environmental Impact: Cavity wall insulation contributes to reducing carbon emissions and environmental impact. By decreasing the amount of energy required to heat or cool a building, it helps to lower greenhouse gas emissions associated with energy production. Using less energy also helps to conserve natural resources and promote sustainability.

5. Dampness Prevention: Cavity wall insulation can assist in preventing dampness issues within the walls. By filling the cavity, it acts as a barrier against moisture penetration from the outside. This helps to reduce the risk of condensation, damp patches, and potential structural damage caused by moisture-related issues.

6. Increased Property Value: Cavity wall insulation can add value to a property. With energy efficiency and sustainability becoming increasingly important factors for potential buyers or tenants, a well-insulated home with lower energy costs can be an attractive feature that enhances the property’s value and desirability.

It’s worth noting that the benefits of cavity wall insulation can vary depending on factors such as the insulation material used, the existing condition of the walls, and the overall insulation performance of the building.

Cavity Wall insulation Installation process

The installation process of cavity wall insulation typically involves the following steps:

1. Initial Assessment: A professional insulation installer will conduct an initial assessment of the property to determine its suitability for cavity wall insulation. They will inspect the

walls, check for any existing insulation or dampness issues, and assess the construction

of the walls to ensure they are suitable for insulation.

2. Preparation: Before starting the installation, the installer will prepare the site by setting

   up the necessary equipment and ensuring the work area is safe and accessible. They may also cover or protect any vulnerable areas, such as windows or landscaping, to prevent damage during the installation process.

3. Drill Access Holes: Small access holes, usually around 22-25mm in diameter, are drilled into the outer wall at regular intervals. The spacing and location of these holes depend on the specific insulation material and installation method being used. The holes are strategically placed to allow for the injection of insulation material into the cavity.

4. Insulation Material Injection: Once the access holes are drilled, the insulation material is injected into the cavity using specialized equipment. The material is typically blown or pumped into the cavity under pressure, ensuring it reaches all areas of the wall cavity. The installer carefully monitors the injection process to ensure the correct amount of insulation material is installed.

5. Hole Sealing: After the insulation material is injected, the access holes are sealed to restore the integrity and appearance of the outer wall. Different methods may be used for sealing the holes, such as using matching mortar or color-matched plugs, depending on the type of outer wall construction and finish.

6. Post-Installation Inspection: Once the installation is complete, the installer may conduct a post-installation inspection to ensure that the insulation has been installed correctly and to address any concerns or questions from the homeowner. They may also provide relevant documentation or certificates confirming the completion of the insulation work.

It’s important to note that the installation process may vary depending on factors such as the insulation material used, the specific equipment and techniques employed by the installer, and the condition of the existing walls.

Cavity Wall insulation grants

In the UK, there have been various government grants and incentives available to encourage the installation of cavity wall insulation and improve energy efficiency in homes. However, it’s important to note that the availability and details of these grants can change over time, so it’s advisable to check with the relevant authorities or government websites for the most up-to-date information. Here are some examples of government grants and incentives that have been offered in the past:

1. Green Homes Grant: The Green Homes Grant was introduced in 2020 as part of the government’s efforts to improve energy efficiency. While the scheme has now closed for new applications, it provided grants of up to £5,000 (or £10,000 for low-income households) to help cover the costs of installing energy-saving measures, including cavity wall insulation.

2. Energy Company Obligation (ECO): The Energy Company Obligation is an ongoing scheme that requires larger energy suppliers to provide funding for energy efficiency

improvements in households. Under ECO, eligible homeowners and tenants may receive financial support for cavity wall insulation, among other energy-saving measures. The eligibility criteria and funding amounts may vary based on factors such as income, property type, and location.

3. Renewable Heat Incentive (RHI): While not specific to cavity wall insulation, the Renewable Heat Incentive is a government scheme that provides financial incentives for installing renewable heating systems, such as heat pumps. Cavity wall insulation can be an additional energy-saving measure that complements the installation of renewable heating systems, and it may contribute to overall energy efficiency.

4. Local Authority Grants: Some local authorities in the UK offer grants or funding schemes to support energy efficiency measures, including cavity wall insulation. These grants are typically specific to certain regions and may have their own eligibility criteria and application processes. It’s advisable to check with your local council to inquire about any available grants or incentives.

It’s important to thoroughly research and understand the specific requirements, eligibility criteria, and application procedures for any grants or incentives before proceeding with cavity wall insulation or any other energy-saving measures. Additionally, engaging with certified and accredited insulation installers who meet the necessary standards is crucial to ensuring compliance with grant requirements and the quality of the insulation work.