Fibreglass Mesh for Construction

Fibreglass mesh is a reinforcing mesh that is embedded in plasters and skim coats to strengthen them and limit cracking. It works well where the substrate is subject to movement or small cracks, such as façades with external wall insulation. Laid in the skim coat, it distributes stresses and helps the plaster stay uniform over time. It does not, however, replace proper preparation of the substrate.

For external wall insulation, fibreglass meshes with an alkali-resistant coating are used, because they must withstand the alkaline environment of the mortar. The grammage, that is the weight per square metre, varies according to the system and the performance required. It is best to choose the mesh specified by the manufacturer of the insulation system, so as to check compatibility with adhesives, skim coats and finishes. In the catalogue you will find insulation meshes from several brands.

Insulation mesh is sized for application over the insulating material and usually has the alkali-resistant coating. Reinforcing mesh for plasters and skim coats strengthens the finishing layer and may come in different sizes and grammages. Fabrics and cloths in rolls are suited to substrates with recurring cracks, because they cover larger surfaces with a single sheet. Always check the data sheet for the intended use.

First the substrate is prepared, clean and stable, then a first layer of skim coat is spread with the trowel. While the skim coat is still fresh, the mesh is embedded, pressing and stretching it well so that no creases remain, and it is covered with a thin layer of finish. The overlaps between sheets must follow the instructions of the system used. Respect the drying times given by the manufacturer before applying the finish.

Anti-crack meshes and fabrics are needed where the substrate is prone to cracking, such as the joints between different materials, the edges of openings and surfaces that expand with temperature. Façades exposed to sun and rain can also benefit from reinforcement. The type of mesh must be chosen according to the cause of the cracking, assessed before the work.

Grammage indicates the weight of the mesh per square metre and generally increases with the strength required. A lighter mesh is fine for finishing skim coats and lightly stressed substrates, while for external insulation and surfaces subject to impact or movement a higher grammage is better. The final choice follows the system and the instructions of the coating manufacturer. Ask for the data sheet before buying.

Fibreglass can irritate skin and eyes, and its particles are released into the air during cutting. Wear gloves, goggles and a dust mask, and cut the sheets outdoors or in a ventilated area. Wash your hands and clothes after work and do not touch your face with dirty gloves. Store the rolls away from damp and read the product's safety data sheet.

Fibreglass meshes are used by thermal insulation contractors, plasterers and anyone carrying out façade refurbishment. They are used in plaster skim coats, to reinforce insulation and where the substrate has cracks. A frequent use is external wall insulation on residential and commercial buildings. Choose the product according to the planned work cycle.