Are you tired of high heating costs and uncomfortable indoor temperatures? External wall insulation is the solution you need. However, the process can seem daunting if you’ve never installed insulation. Now you may be thinking about how to install external wall insulation.
To install external wall insulation, you’ll need insulation boards, fixings, adhesive, reinforcement mesh, base coat, and top coat. The process involves preparing the walls, attaching the insulation boards, installing the reinforcement mesh, applying the base coat, and finishing with the top coat.
In this article, we’ll guide you through installing external wall insulation. You’ll learn what materials you need, how to prepare your walls, and the step-by-step installation process. So, read on to learn everything you need to know about installing external wall insulation.
Why Is External Wall Insulation Important For Your House?
Installing external wall insulation will give you several benefits. Below are the reasons why external insulation is important for your home:
- Energy Savings: External wall insulation significantly reduces heat loss through the walls and accounts for up to 35% of heat loss in poorly insulated homes. This leads to significant energy savings and lower heating bills.
- Increased Comfort: By reducing heat loss, external wall insulation makes the interior of your home feel warmer and more comfortable. External wall insulation is beneficial in colder climates or during winter months.
- Reduced Carbon Footprint: External wall insulation reduces energy consumption and greenhouse gas emissions, helps lessen your carbon footprint, and contributes to a more sustainable future.
- Improved Soundproofing: It also helps reduce outside noise and improve soundproofing in your home.
- Enhanced Weather Protection: External wall insulation provides an additional layer of protection for your home’s exterior walls, helping to protect them from weather damage and extend the life of your building’s structure.
- Increased Property Value: This wall insulation increases your home’s energy efficiency and overall value, making it more attractive to potential buyers and improving its resale value.
What Are The Materials Needed For External Wall Insulation?
Before starting the external wall insulation installation process, you’ll need to gather all the necessary materials and tools to ensure a smooth and successful installation. Below are some materials you will require for the process.
ProGuard Exteriors are your local experts for external wall insulation, exterior wall coatings, coloured render systems, and exterior painting for your home.
ProGuard Exteriors are your first choice for quality local workmanship throughout the South East of England.
Call us today on 0800 612 5254 to arrange a free quote or get in touch for more information on how to protect and transform your home!


Insulation Material
Insulation board is a key material for external wall insulation. It is typically made of rigid foam material, such as expanded polystyrene (EPS), extruded polystyrene (XPS), or polyurethane (PUR). The insulation board is attached to the exterior walls of the building to provide thermal insulation and improve energy performance.
Fixings
Fixings are materials needed for external wall insulation that is used to attach the insulation board to the exterior walls of the building. They include screws, nails, other mechanical fixings, and adhesives.
Adhesive
The adhesive is needed to install external wall insulation to bond the insulation board to the exterior wall surface. The adhesive creates a strong and durable bond between the insulation board and the wall, helping to ensure that the insulation remains securely in place.
Reinforcement Mesh
Reinforcement mesh is a material needed for external wall insulation that is used to reinforce the base coat and improve the strength and durability of the insulation system. The mesh is typically made of strong and flexible material, such as fibreglass or synthetic fibres, and is applied over the base coat while it is still wet.
The mesh is then embedded into the base coat and allowed to dry, creating a strong and durable insulation layer that can withstand weathering and other stresses.
Base Coat
The base coat is needed for external wall insulation that is applied over the insulation board and reinforcement mesh. It is typically a cement-based mixture that provides a smooth and level surface for the top coat. The base coat also helps to protect the insulation board and reinforcement mesh from weathering and other stresses.
Top Coat
The top coat is needed for external wall insulation applied over the base coat to provide additional protection and a decorative finish. It is typically a textured or smooth finish customised to meet the design requirements of the building. The top coat also helps to protect the insulation system from weathering and other stresses.
Cutting Tools
Cutting tools such as a saw or knife are essential for external wall insulation. These tools cut the insulation boards to the appropriate size and shape to fit the walls. It is important to have sharp, precise cutting tools to ensure clean cuts and accurate fitting of the insulation boards.
Measuring Tools
Measuring tools such as tape measure and level are necessary for external wall insulation. These tools measure and mark the appropriate dimensions for the insulation boards and ensure they are installed evenly and accurately. It is important to have precise measuring tools to ensure the insulation boards fit properly and provide effective insulation.
Safety Equipment
Safety equipment such as goggles, gloves, and masks are important materials for external wall insulation. These materials help protect workers from hazardous materials and keep them safe during insulation installation. Goggles and masks protect the eyes and respiratory system from insulation dust and other airborne particles, while gloves protect hands from chemical adhesives and sharp tools.

How To Prepare For External Wall Insulation?
After gathering all the necessary materials and tools, you have to prepare the exterior walls of your home properly. Here are some key steps in the preparation process:
1. Inspect The Walls
Inspection of walls involves thoroughly examining the exterior walls of the building to identify any structural issues, cracks, or gaps that could affect the installation of the insulation system. The inspection will also help determine the suitability of the walls for the selected insulation system.
2. Clean The Walls
Cleaning the walls involves removing any dirt, debris, or other contaminants to create a clean and smooth surface for the insulation system. In that case, you can use various methods, such as pressure washing, scrubbing with a brush and detergent, or using a chemical cleaner.
The specific cleaning method will depend on the insulation type of wall surface, and the extent of the cleaning required. Proper cleaning ensures the insulation system adheres to the wall surface and performs effectively.
3. Check For Moisture
Before you install external wall insulation, check for any signs of moisture build-up or dampness on the walls. It should be addressed before proceeding with insulation installation if moisture is present.
4. Remove Obstacles
Removing obstacles involves clearing any obstructions, such as plants, furniture, or outdoor fixtures, from the area around the walls to be insulated. This allows easy access to the walls and ensures that the insulation system is installed correctly without hindrance.
Obstacles also prevent proper cleaning of the walls, affecting the insulation system’s performance. However, you should clear the area around the walls before beginning the installation of the insulation system to ensure a smooth and effective process.
5. Seal Gaps And Openings
Sealing gaps and openings include filling any cracks or gaps with appropriate sealant, sealing around windows and doors, and ensuring that electrical or plumbing penetrations are properly sealed to prevent air leakage. This will help improve the insulation’s effectiveness and prevent drafts and moisture infiltration.
6. Allow For Ventilation
Before you install external wall insulation, allow for proper ventilation to prevent moisture build-up and potential damage to the insulation. Ventilation is achieved by creating vents in the eaves and installing appropriate breathable materials.
7. Fixing Any Structural Issues
Fixing any structural issues involves identifying and repairing any structural problems in the walls, such as cracks, gaps, or damage to the building’s foundation. Structural issues affect the insulation system’s performance and require specialist expertise to repair it.
How To Install External Wall Insulation?
With proper preparation, it’s time to move on to the external wall insulation installation phase. This crucial step involves carefully applying the insulation system to the wall surface to ensure it effectively improves the building’s energy efficiency and thermal performance. Now we will put light on the steps of installing external wall insulation.
Step 1: Placement Of Insulation Boards
Placement of insulation boards is positioning the insulation boards onto the cleaned and prepared wall surface using the appropriate fixings and adhesive. The insulation boards are typically made of expanded polystyrene, mineral wool, or polyurethane foam.
They are chosen based on their thermal performance and suitability for the particular building. Proper placement of the insulation boards is essential to ensure that the insulation system effectively improves the building’s energy efficiency and thermal performance.
Step-2: Attaching Insulation Boards To The Wall
Attach insulation boards to the wall using the appropriate fixings and adhesive to attach the insulation boards to the prepared wall surface. The type of fixings and adhesive used will depend on the specific insulation system being installed and the materials used in building construction.
Proper attachment of the insulation boards will ensure that the insulation system effectively reduces heat loss and improves the building’s energy efficiency.
Step-3: Installing The Reinforcement Mesh
Installing the reinforcement mesh is a critical step in installing external wall insulation. The reinforcement mesh is typically made of fibreglass or plastic and provides added strength and stability to the insulation system. The mesh is applied over the insulation boards and is fixed to the wall surface using mechanical fixings or adhesive.
The mesh is then coated with a base coat, reinforcing the system and creating a smooth surface for applying the topcoat. Proper installation of the reinforcement mesh is important to ensure that the insulation system withstands weathering, movement, and other stresses over time.
Step-4: Applying The Base Coat
Applying the base coat is a key step in installing external wall insulation. The base coat is typically a cementitious material applied over the reinforcement mesh to provide additional strength and stability to the insulation system.
Depending on the installed insulation system, the base coat is applied in one or more layers using a trowel or spray equipment. Proper application of the base coat will help create a smooth and even surface for applying the topcoat and ensure that the insulation system can withstand weathering and other stresses over time.
Step-5: Applying The Top Coat
Applying the top coat is the final step in installing external wall insulation. The top coat is a decorative and protective finish applied over the base coat to provide an attractive appearance and protect the insulation system from weathering and other external stresses.
This coat is made from various materials, including acrylic, silicone, or mineral-based finishes, and applied in a range of colours and textures to suit the specific design requirements of the building.
The top coat is applied using a trowel, spray equipment, or a roller and is typically applied in one or more layers, depending on the manufacturer’s recommendations. Proper top coat application ensures the insulation system is fully protected and provides optimal performance over its expected lifespan.
What Are The Finishing Touches For External Wall Insulation?
After completing the installation of external wall insulation, there are a few finishing touches that are necessary to ensure that the job is done properly. We will discuss them here:
Cleaning Up The Workspace
Once the installation is complete, remove any excess adhesive, debris, or other materials from the work area to ensure the installation is clean and tidy. This involves sweeping, vacuuming, or washing the work area and disposing of waste materials per local regulations.
Cleaning the workspace also helps prevent accidents or injuries by removing any hazards or obstacles.
Restoration Of Any Damaged Finishes
The installation process requires removing or altering some of the existing finishes on the walls, such as paint or plaster. You should restore these finishes to their original condition once the installation is complete. Repainting or re-plastering the affected areas to match the surrounding surfaces.
Restoration of any damaged finishes helps to ensure that the final result is not only energy-efficient and weather-resistant but also visually appealing and in keeping with the overall aesthetic of the building.
Inspection Of The Installed Insulation
Once the installation is complete, inspecting the insulation to ensure it has been properly installed and performs as expected is important. In that case, you should check for gaps, cracks, or other defects in the insulation and the insulation’s overall thickness and coverage.
Any issues or concerns should be addressed promptly to ensure that the insulation provides maximum energy efficiency and weather protection.
How To Maintain And Care For External Wall Insulation?
Proper maintenance and care are important for ensuring external wall insulation’s long-term effectiveness and performance. Here are some key tips for maintaining and caring for your external wall insulation:
- Regular Cleaning: Dirt, debris, and other contaminants can accumulate on the surface of your insulation over time, which can reduce its effectiveness. Regular cleaning can help to remove these contaminants and keep your insulation in good condition.
- Check for Damage: Inspect your insulation periodically for any signs of damage, such as cracks, gaps, or other defects. Address any issues promptly to prevent them from becoming more serious problems.
- Check for Pests: External wall insulation can be attractive to pests such as rodents and insects. Regularly inspect your insulation for any signs of pest infestation and take appropriate measures to address the problem.
- Monitor Energy Usage: Keep track of your energy usage over time to ensure that your insulation performs as expected. If you notice any significant changes in your energy bills, it may be a sign that your insulation needs to be inspected or repaired.
- Professional Inspection and Maintenance: Consider having your insulation inspected and maintained by a professional regularly. A professional can identify and address any issues before they become more serious and can help ensure that your insulation provides maximum energy efficiency and weather protection.

What Are The Common Mistakes To Avoid While Installing External Wall Insulation?
Some common mistakes people make when installing external wall insulation affect the insulation’s effectiveness and durability. Here are some mistakes to avoid:
- Incorrect installation of the insulation board, such as not using enough adhesive or not securing the board properly to the wall.
- Not allowing for proper ventilation leads to moisture build-up and mould growth.
- Failing to seal gaps and openings properly can allow air to leak in and out of the home and decrease the insulation’s effectiveness.
- Not addressing any underlying structural issues before installation causes the insulation to fail over time.
- Using the wrong type of insulation for the climate or location.
- Skimping on materials or installation steps to save money results in a lower quality installation and reduced effectiveness of the insulation.
- Ignoring safety protocols and failing to use proper safety equipment during installation can lead to injury or accidents.
Final Words
From now on, you should know how to install external wall insulation by reading the guide above. By following the steps outlined in this article and seeking the assistance of a professional if needed, you can achieve a successful installation that will provide lasting benefits for your home and your wallet.
In general, external wall insulation system is an essential investment for your home, providing numerous benefits such as energy efficiency, cost savings, and improved comfort. However, it is crucial to ensure proper installation and maintenance to maximise these benefits and prolong the lifespan of the insulation.