Fibreglass mesh is essential in external wall insulation (EWI) and rendering systems, providing durability, strength, and flexibility. But why exactly do you need it, and how does it improve the overall performance of your project?

What is fibreglass mesh?

Fibreglass mesh is a reinforcement material used in external wall insulation (EWI) and render systems to enhance their strength, durability, and resistance to cracking. It is made from thin, woven fibreglass strands and is typically embedded into the basecoat layer to provide a solid foundation. Fibreglass mesh is designed to absorb and distribute stress across the surface of the render or insulation system, preventing cracks from forming due to thermal expansion, contraction, or movement within the structure.

One key benefit of fibreglass mesh is its versatility. It comes in different grades or weights, measured in grams per square metre (gsm).

Panzer Mesh

Panzer Mesh is a type of fibreglass mesh that provides enhanced reinforcement for areas that require extra strength. This heavy-duty mesh is usually made with a higher gsm, offering significantly more durability compared to standard fibreglass meshes. It is typically used in areas that are more vulnerable to impact or require additional support, such as around doorways, windows, or ground floors where mechanical damage is more likely.

Panzer mesh typically weighs around 300-350 gsm, making it much thicker and stronger than standard fibreglass mesh. This extra strength ensures that vulnerable areas of the render or insulation system are well protected, reducing the risk of damage and extending the system’s lifespan.

GSM of various meshes

The gsm (grams per square metre) rating of fibreglass mesh refers to its density and strength. Different GSM ratings are used depending on the specific requirements of the project:

• 145-160 gsm Mesh: This is the standard mesh used in most external wall insulation (EWI) and render systems. It provides a good balance of flexibility and strength, making it suitable for general reinforcement. It’s lightweight and easy to work with, offering adequate protection against cracking and weathering.
• 300-350 gsm Mesh (Panzer Mesh): This heavy-duty mesh provides extra reinforcement in areas more prone to damage. It is often applied in high-traffic areas or lower building parts, where the impact risk is higher. Panzer mesh provides added protection without compromising the system’s flexibility.
• 100-110 gsm Mesh: Lighter mesh may sometimes be used for less critical applications like IWI. This mesh is typically not suitable for areas that experience significant stress or movement. Still, it can be used in minor repairs or for reinforcing less vulnerable parts of a building.

Why use fibreglass mesh?

1. Prevents Cracking – One of the main reasons fibreglass mesh is used in render and EWI systems is to prevent cracking. Over time, buildings are exposed to thermal expansion and contraction due to changes in weather conditions. This natural movement can cause hairline cracks to appear in the render. By embedding fibreglass mesh into the basecoat, the system can better absorb and distribute stresses across the surface, reducing the likelihood of cracks forming.
2. Improves Durability – Fibreglass mesh adds additional strength to external wall systems. Its tensile strength makes it resistant to impacts, weathering, and even shrinkage. This increased durability means that your render or EWI system will last longer and maintain its appearance.
3. Resists Moisture and Mould – Another advantage of fibreglass mesh is its moisture resistance. In render systems, especially in the UK where wet weather is common, moisture ingress can be a significant concern. The fibreglass material doesn’t absorb water and helps the render layer remain impermeable, reducing the risk of dampness or mould forming inside the building structure.
4. Enhances Insulation Performance – In EWI systems, fibreglass mesh plays a vital role in maintaining the integrity of the insulation layer. By reinforcing the basecoat, the mesh helps protect the insulation boards from mechanical damage and ensures that the insulation remains effective for longer. This is crucial in ensuring the energy efficiency of the building remains high, saving on heating costs and reducing carbon emissions.
5. Flexibility for Different Surfaces – Fibreglass mesh is compatible with various surfaces, including brick, concrete, and timber. Its flexibility allows it to accommodate irregular surfaces, making it an excellent choice for both new builds and renovation projects, particularly on older properties with uneven substrates.