Why use Fibreglass Mesh in Render Systems?

Fibreglass Mesh is an essential component of our render systems. It helps to provide strength and flexibility to our thin coat render systems, ensuring that the render remains crack resistant for years to come.

Fibreglass Mesh is made of neatly woven fibreglass thread. This type of mesh is widely used in plastering and rendering for wall reinforcement, external wall insulation and roof waterproofing. We offer different weights of mesh depending on the intended use and, typically, heavier mesh provides more impact resistance within the render system. At EWI Store, the heaviest mesh we sell is our Panzer Mesh at 350g/m²  and this is often used in areas that are likely to endure heavy impacts e.g. a wall where a football is kicked against it.

All of the mesh we sell is alkali-resistant. This helps prevent it from being broken down by the chemicals in the other mortars and adhesive materials.

Where do you put the Fibreglass Mesh in render systems?

The Fibreglass Mesh is embedded within the basecoat layer within both render and external wall insulation systems. The mesh needs to be embedded within the basecoat while it is still wet, and we always recommend getting the mesh embedded within the middle of the layer of the basecoat, rather than too close to the surface or sitting right next to the wall.

In thin coat render systems, the basecoat thickness is normally between 4-8mm, so installers tend to have different embedding techniques.

A notched trowel can be used to apply the basecoat to the wall at the required thickness and then the mesh can be tapped into the basecoat. A straight-edged trowel can then be used to ‘pull’ the adhesive through the mesh by applying pressure to the basecoat.

Other installers will apply a thinner first pass of adhesive, then tap the mesh in place, then apply a second layer of the basecoat. Either method is absolutely fine however, if you do go with the second method, ensure the first pass of basecoat has not dried before applying the second pass of mesh; the mesh needs to be embedded within a fully wet product.

Overlapping mesh in basecoat

During weather and temperature changes, the external walls of your home expand and contract minutely due to the heating and cooling processes. Mesh is used to help the system ‘flex’ with these building movements to help prevent cracking. 

All our mesh comes with markings 100mm from each end. This marking illustrates the overlap of the mesh required when installing it. Each strip of the mesh needs to overlap the last by 100mm otherwise cracks can appear in this area over time.

The mesh provides additional strength to all thin coat render systems and helps prevent cracking, so we highly recommend it if you want to ensure the structural stability of your system!

Below is an example of a buildup for Render-Only on a brick substrate which demonstrates where the Fibreglass Mesh fits into the process. 

To see how we test the strength of our Silicone render system with and without mesh, please watch our YouTube video “Silicone Render Impact Test“.