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Cavity Wall Insulation

If your home was constructed post-1930s, chances are its external walls consist of two layers with a gap of around 50mm between them, making them cavity walls. This gap presents an opportunity to install cavity wall insulation and prevent heat loss to the outdoors.

How to Identify Cavity Walls

To determine if your home has cavity walls, inspect the brickwork. If the bricks display only their long sides, as shown in this image, your home likely has cavity walls. In contrast, if the bricks exhibit an alternating long-short-long-short pattern, like the example below, your home probably has solid walls

two different brickwork styles showing difference between solid and cavity wall

Visual Inspection of Brickwork

Begin by closely examining the brickwork on the exterior of your home. The pattern and arrangement of bricks can provide valuable insights into the wall structure. Here’s what to look for:

  1. Cavity Walls:

If the bricks predominantly showcase only their long sides, forming a consistent and uninterrupted pattern, it indicates the likelihood of cavity walls. This means there is an open space, or cavity, between the inner and outer layers of your walls.

2. Solid Walls:

In contrast, solid walls present a distinctive pattern. If the bricks display an alternating long-short-long-short arrangement, it suggests the absence of a cavity. The bricks form a more textured and varied surface, indicating a solid wall structure.

Additional Tips for Identification

  • Check Multiple Areas: Inspect different sections of your exterior walls, as architectural designs may vary. Ensure your observations are consistent across various parts of your home.
  • Consult Building Plans (if available): If you have access to the original building plans, they can offer explicit details about the wall construction. Check with local authorities or the builder for any available documentation.
  • Professional Assessment: When in doubt, seek the expertise of a qualified professional. Registered installers or building assessors can provide accurate insights into your wall structure through advanced tools and knowledge.

Why Identification Matters

Understanding whether your home has cavity or solid walls is crucial for several reasons:

  • Insulation Suitability: Cavity walls allow for insulation, making your home more energy-efficient. Identifying the wall type helps determine if cavity wall insulation is a viable option.
  • Maintenance Considerations: Different wall types may require varied maintenance approaches. Knowing your wall structure aids in planning and addressing any potential issues effectively.
  • Renovation and Remodelling: If you plan to renovate or remodel your home, knowing the wall construction type is essential for making informed decisions about structural changes.

By carefully examining your brickwork and considering additional factors, you can confidently determine whether your home has cavity walls and proceed with informed choices for insulation and maintenance. If uncertain, consulting with a professional ensures accurate identification and guidance tailored to your specific home structure.

Benefits of Cavity Wall Insulation

Cavity wall insulation can lead to significant savings on heating bills, often paying for itself quickly. Additionally, grants and offers are available to help offset the cost of installation.

1. Substantial Energy Savings:

Cavity wall insulation acts as a thermal barrier, preventing heat loss from your home. By creating an efficient insulation layer within the walls, your heating system operates more effectively. This translates to a significant reduction in energy consumption, leading to lower heating bills. In fact, the insulation’s cost savings often result in a rapid return on your initial investment, making it a financially astute decision for the long term.

2. Financial Viability and Payback Period:

One of the standout features of cavity wall insulation is its ability to pay for itself over time. The upfront investment is outweighed by the ongoing savings on energy bills. The payback period is notably short, allowing homeowners to recoup their initial costs and continue enjoying reduced energy expenses for the lifespan of the insulation.

3. Access to Grants and Financial Incentives:

Governments and energy efficiency programs often provide grants and incentives to encourage homeowners to adopt energy-saving measures like cavity wall insulation. These financial support mechanisms aim to make the transition to more sustainable practices more accessible and affordable. By taking advantage of these grants, you not only reduce the burden of installation costs but also contribute to a greener, more energy-efficient future.

4. Environmental Impact:

Cavity wall insulation contributes to environmental sustainability by curbing the carbon footprint of your home. The reduced energy consumption means fewer greenhouse gas emissions associated with heating, fostering a more eco-friendly living environment. As part of a broader commitment to environmental responsibility, cavity wall insulation aligns with global efforts to mitigate climate change and promote energy efficiency.

5. Enhanced Comfort and Temperature Regulation:

Beyond financial considerations, cavity wall insulation enhances the overall comfort of your living space. By maintaining a consistent indoor temperature, insulation eliminates cold spots and drafts, creating a more pleasant and cozy atmosphere throughout your home. This improvement in thermal comfort is particularly noticeable during colder seasons.

6. Property Value Appreciation:

A home equipped with cavity wall insulation often enjoys enhanced property value. Potential buyers recognize the long-term cost savings and energy efficiency associated with a well-insulated home, making it an attractive feature in the real estate market.

side on image of cavity wall insulation being installed

Is Your Home Suitable for Cavity wall Insulation?

Your home is likely suitable for cavity wall insulation if:

  • It has unfilled cavity walls.
  • The masonry and brickwork are in good condition.
  • The cavity is at least 35mm wide (or 50mm for certain insulation types).

However, refrain from installing cavity wall insulation if your home exhibits:

  • Poor maintenance or structural issues.
  • Evidence of rising or penetrating damp.
  • Dirty cavities, wall ties, or builder’s rubble in the cavity.
  • Exposure to extreme weather conditions or driving rain.
  • Issues such as overflowing or blocked guttering.

Installation Process

Professional installers typically insulate cavity walls by drilling small holes into the mortar at regular intervals and injecting insulation material into the cavity. The holes are then refilled. Rigid insulation boards may be used in new-build properties.

Choosing the Right Material

Polystyrene beads, with a carbon coating for enhanced performance, are the most common material due to their effectiveness at retaining heat and resistance to moisture absorption. They are quicker to install, reaching awkward areas without extensive drilling, reducing the need for patching up and scaffolding.

Cost and Savings For Cavity Wall Insulation

The Energy Saving Trust and the National Housing Model estimate the following savings based on a gas-heated home:

Property TypeTypical Installation CostEnergy Bill Saving
Detached House£1,800£475/year
Semi-detached House£1,000£361/year
Mid-terrace House£580£203/year
Detached Bungalow£800£337/year
Purpose-built Flat£395£234/year
Comparing cavity wall insulation costs in different properties

The investment pays for itself in about three years. Larger homes or those heated by electricity or oil may experience even greater savings.

Professional Installation

Cavity wall insulation is not a DIY job. Only registered installers affiliated with professional bodies like The National Insulation Association (NIA), The Cavity Insulation Guarantee Agency (CIGA), or The British Board of Agrément should perform the installation. Ensure that your installer follows a code of professional practice and provides a 25-year guarantee through CIGA.

cavity wall insulation being professionally installed

Addressing Concerns About Damp

Contrary to common belief, properly installed cavity wall insulation does not cause damp. Only a small percentage of the 4 million UK homes with retrofitted insulation have reported damp issues directly linked to insulation. Any water penetration is usually due to pre-existing defects in the property’s construction, which can be identified and remedied during a proper assessment before insulation installation.

Guarantee for Peace of Mind

Reputable installers are registered with the Cavity Insulation Guarantee Agency (CIGA), offering a 25-year guarantee covering issues arising from faulty or inappropriate insulation installation. If you have existing cavity wall insulation and concerns, contact CIGA to verify the status of your guarantee.

ensure your home stays warm and energy-efficient with professionally installed cavity wall insulation. For personalized advice, always consult with a registered installer.