Choosing the right materials is an important part of planning an external wall insulation (EWI) system. An EWI installation is made up of several layers and components, so the insulation board is only one part of the overall specification.
From insulation boards and fixings to reinforcing mesh, basecoat and external render, each material needs to be appropriate for its intended application and compatible with the wider system.
In this guide, we look at the key factors to consider when choosing EWI materials for an external wall insulation system.
What Are EWI Materials?
EWI materials are the products and components used to build an external wall insulation system on the outside of a building.
Depending on the system, these can include:
- EWI insulation boards
- Insulation adhesive
- Insulation fixings and anchors
- Reinforcing mesh
- Base tracks
- Corner beads and other profiles
- Basecoat
- Render primer
- External render
- EWI accessories
The exact combination will depend on the selected system, building and installation requirements.
Start With the Insulation Board
The insulation board is one of the main components of an EWI system. It forms the insulation layer that is installed externally onto the building wall.
EPS insulation boards are one type of board used in EWI applications. When choosing an insulation board, consider the required:
- Board type
- Thickness
- Dimensions
- System specification
- Compatibility with other materials
The correct board should be selected according to the requirements of the particular project rather than simply choosing the thickest or lowest-cost option.
Choose the Right Insulation Fixings
Mechanical fixings can form an important part of an external wall insulation system. Insulation fixings or anchors are used to secure insulation boards to the substrate in accordance with the system specification.
The appropriate fixing can depend on:
- Wall substrate
- Insulation thickness
- Fixing requirements
- Type of fixing
- EWI system specification
For this reason, fixings should be selected alongside the insulation system rather than treated as a completely separate purchase.
Consider the Adhesive and Basecoat
Adhesive is used within the EWI build-up to attach insulation boards to the wall. Basecoat is then used as part of the reinforced layer over the insulation.
Some products may have specific adhesive and basecoat applications, while others are designed for a particular stage of the system.
Always check the manufacturer's product information to establish how the material is intended to be used.
Select Suitable Reinforcing Mesh
Reinforcing mesh is incorporated into the basecoat layer and forms part of the reinforced surface beneath the final render.
Fibreglass mesh is commonly available for suitable EWI and render applications.
When choosing insulation mesh, check the product specification and ensure that it is intended for the particular system and application.
Don't Forget EWI Profiles and Accessories
An external wall insulation system can require more than boards, adhesive and mesh. Profiles and accessories may also be needed to deal with edges, corners, openings and the starting point of the insulation.
These can include:
- Base tracks
- Corner beads
- Stop beads
- Profiles with mesh
- Other EWI accessories
The correct profile will depend on its location and the requirements of the installation.
Choosing the Right Render System
The external render is the visible finishing layer of an EWI system, so the choice of render is an important part of the overall specification.
Different render products and finishes are available, including silicone render and other external render options.
When comparing render products, consider:
- Render type
- Finish
- Colour
- Manufacturer requirements
- Primer requirements
- Compatibility with the underlying basecoat
The render should be considered as part of the complete system rather than selected independently from the other EWI materials.
Check Material Compatibility
One of the most important considerations when choosing EWI materials is compatibility.
An external wall insulation system contains multiple layers that work together. For example:
Wall → Adhesive → Insulation Board → Fixings → Basecoat & Reinforcing Mesh → Primer → External Render
The exact build-up can vary between systems.
Before purchasing individual materials, check the relevant product and system documentation to confirm that the components are suitable for the intended application.
Consider the Building and Substrate
The building itself also influences the choice of EWI materials.
The wall substrate, existing surface, insulation requirements and proposed finish should all be considered before materials are ordered.
For example, the type of insulation fixing required can depend on the substrate, while the insulation board and render need to fit the overall system specification.
This is why choosing EWI materials should start with understanding the project rather than selecting products individually.
Buying EWI Materials for a Trade Project
For larger building projects, it can be useful to plan the complete list of required materials before ordering.
A typical EWI materials list may include:
- Insulation boards
- Adhesive
- Mechanical fixings
- Base tracks
- Profiles and beads
- Reinforcing mesh
- Basecoat
- Primer
- External render
- Related accessories
Planning the materials together can make it easier to identify missing components and ensure that the selected products are appropriate for the intended system.
Where to Buy EWI Materials in the UK
Infinity PM supplies a range of EWI materials for trade and building projects, including insulation boards, insulation fixings, reinforcing mesh, basecoat products, profiles and render materials.
Customers can explore the EWI range and compare products according to their individual specifications and project requirements.
For related products, explore the External Wall Insulation, EWI Materials, EWI Insulation Boards, Insulation Fixings, Insulation Mesh, Render Systems and Silicone Render categories.
Final Thoughts
Choosing EWI materials is about creating a suitable combination of products rather than selecting individual materials in isolation.
From EWI insulation boards and mechanical fixings to reinforcing mesh, basecoat, primer and external render, each component has a role within the overall system.
Before ordering materials, check the relevant specifications, system requirements and compatibility of the products. This helps ensure that the materials selected are appropriate for the intended external wall insulation project.
FAQs
What are the main materials used in an EWI system?
Common EWI materials include insulation boards, adhesive, mechanical fixings, reinforcing mesh, profiles, basecoat, primer and external render.
How do I choose EWI insulation boards?
Consider the board type, thickness, dimensions and requirements of the EWI system. The selected board should be suitable for the intended application and compatible with the other system components.
Are insulation fixings important for EWI?
Yes. Where mechanical fixings are specified, the correct fixing should be selected according to factors such as the substrate, insulation thickness and system requirements.
What type of mesh is used for external wall insulation?
Fibreglass reinforcing mesh is available for suitable EWI applications. Always check the manufacturer's specification for the particular system.
Can I choose EWI materials separately?
Individual materials should not be selected without considering compatibility. Check the relevant system and manufacturer requirements before combining products.
What render should I use with EWI?
The appropriate render depends on the EWI system, basecoat, primer and desired finish. Silicone render and other external render products may be available depending on the system specification.