External wall insulation (EWI) is a complete system made up of several different materials and components. Choosing the right insulation board alone is not enough. A typical EWI installation can require insulation boards, fixings, adhesive, reinforcing mesh, profiles, basecoat, primer, and an external render finish.
In this guide, we look at the main external wall insulation materials you may need and explain the role each component plays within an EWI system.
What Materials Are Needed for External Wall Insulation?
The exact materials required depend on the EWI system, building and specification. However, common EWI materials include:
- External wall insulation boards
- Insulation adhesive
- Insulation fixings and anchors
- Reinforcing mesh
- Base tracks and profiles
- Basecoat
- Render primer
- External render
- Beads and other EWI accessories
These components work together as part of the overall external wall insulation system.
1. External Wall Insulation Boards
The insulation board forms the main insulating layer of an EWI system. Boards are installed externally onto the building wall before the reinforcement and render layers are applied.
Different insulation materials and board specifications are available, so the appropriate product should be selected according to the requirements of the project and the system being installed.
EPS insulation boards are one example commonly associated with EWI applications. When choosing insulation boards, consider the required thickness, dimensions, system specification, and compatibility with the other materials.
2. Insulation Adhesive
Insulation adhesive is used to attach insulation boards to the external wall.
The adhesive needs to be appropriate for the insulation board and EWI system being used. Correct preparation and application are important because the adhesive forms part of the connection between the insulation layer and the substrate.
For a complete system, always check the manufacturer's product information and installation requirements.
3. Insulation Fixings and Anchors
Mechanical insulation fixings provide additional attachment for insulation boards. Depending on the EWI specification, fixings can include anchors with different pin and head configurations.
The appropriate fixing depends on factors such as the substrate, insulation thickness, and system requirements.
It's important not to select fixings based only on price or appearance. The fixing must be suitable for the particular application and compatible with the insulation system.
4. Reinforcing Mesh
Reinforcing mesh is incorporated into the basecoat layer over the insulation boards. Fibreglass mesh is commonly used for reinforcement within suitable EWI systems.
The mesh helps form the reinforced layer onto which the subsequent finishing materials can be applied.
Mesh is therefore an important part of the EWI build-up rather than simply an optional accessory.
5. Base Tracks and Profiles
Base tracks are installed at the bottom of an EWI system and provide a starting profile for the first row of insulation boards.
Other profiles and beads can also be required around corners, openings, and other areas of the building. These components help create defined edges and support the detailing of the system.
The correct profile should be selected according to the insulation thickness and the requirements of the EWI installation.
6. Basecoat
The basecoat is applied over the insulation and works with the reinforcing mesh to create the reinforced layer of the EWI system.
Basecoat products can have different specifications and applications. Some products may also have adhesive and basecoat functions, depending on the manufacturer's system.
Always check the product specification to confirm how a particular material is intended to be used.
7. Render Primer
A render primer can form part of the preparation for the final render finish. Its purpose and application depend on the render system and manufacturer.
Using the appropriate primer helps ensure that the finishing layers are compatible with the underlying system.
The primer should therefore be selected as part of the complete render specification rather than as a standalone product.
8. External Render
The final render provides the visible finish to an EWI system. Different types of external render are available, including silicone and other render formulations.
The choice of render can affect the appearance and overall specification of the finished external wall.
When selecting a render, consider the manufacturer's system requirements, available finish and colour options, and compatibility with the basecoat and primer.
Why Is It Important to Use Compatible EWI Materials?
An EWI system consists of multiple layers that need to work together. Using individually selected products without checking compatibility can create problems with the overall system specification.
When sourcing external wall insulation materials, consider the complete build-up:
Wall → Adhesive → Insulation Board → Mechanical Fixings → Basecoat & Reinforcing Mesh → Primer → External Render
The exact construction can vary depending on the chosen system and manufacturer.
Choosing External Wall Insulation Materials
Before ordering EWI materials, establish the requirements of the project. Important considerations include:
- Type and thickness of insulation board
- Wall substrate
- Required fixings
- Adhesive or basecoat specification
- Reinforcing mesh
- Required profiles and beads
- Render type
- Render colour and finish
- Manufacturer's system requirements
- Quantity of each material required
Buying the materials as part of a properly specified system can make it easier to ensure that the different components are suitable for the intended application.
Where Can You Buy EWI Materials?
Infinity PM supplies a range of EWI materials for trade and building projects, including EPS insulation boards, insulation fixings, reinforcing mesh, basecoat products, profiles, and render-related materials.
The range includes products from established manufacturers and components used across external wall insulation and render applications.
Before purchasing, check the individual product specifications and make sure the selected materials are appropriate for the intended EWI system.
Final Thoughts
External wall insulation is not just about choosing an insulation board. A complete installation can require several materials, including EWI insulation boards, adhesive, insulation fixings, reinforcing mesh, profiles, basecoat, primer, and external render.
Choosing compatible materials and following the relevant system and manufacturer requirements is important when planning an EWI project.
If you're sourcing materials for an EWI installation, explore the EWI Materials, External Wall Insulation, EWI Insulation Boards, Insulation Fixings, Insulation Mesh, and Render Systems categories at Infinity PM.
FAQs
What materials do I need for external wall insulation?
Typical EWI materials include insulation boards, adhesive, mechanical fixings, reinforcing mesh, profiles, basecoat, primer, and external render. The exact specification depends on the system.
What are EWI insulation boards?
EWI insulation boards form the main insulation layer installed externally onto the building wall. Different board types, thicknesses, and specifications are available.
Do external wall insulation boards need fixings?
Many EWI systems use mechanical fixings in addition to adhesive. The required fixing type and installation method depend on the system, substrate, and insulation specification.
What is reinforcing mesh used for in EWI?
Reinforcing mesh is incorporated into the basecoat layer to form part of the reinforced layer beneath the final render finish.
Can I mix different EWI materials from different systems?
You should check manufacturer and system requirements before combining products. Materials should be compatible and suitable for the intended EWI specification.
What is the final layer of an EWI system?
The final visible layer is generally an external render finish, although the exact finishing system depends on the products and specification selected.