Installation guides

Installing natural stone tiles reinforced with fiberglass mesh

Impurities and inclusions that occur naturally in the crystalline structure during formation weaken stone and, in some cases, make it crumbly, so it can no longer serve as a building material. Reinforcing natural stone tiles then becomes necessary, and bonding mesh to their back solves the problem. This ensures not only that the tiles can be used safely, but also that they can be transported and handled safely. Applying mesh evenly with resin disperses stress across the tile, increasing its strength while significantly reducing the risk of cracking.

This isn’t the only method available. Reinforcing with metal or fiberglass rods is also used, especially in areas facing significant mechanical stress. Another method is bonding slabs onto a wood or plywood backing, or mounting them on a stainless steel frame, an option chosen for public projects.

Going back to reinforcing tiles by bonding mesh to them, this method is also used with concrete.

Fiberglass mesh applied to the back of natural stone tiles has properties that make it suitable for specific design projects. Here are some of the properties needed:

• good mechanical strength

• superior corrosion resistance

• resistance to acidic and alkaline chemicals

• good resistance to high temperatures

• dimensional stability

• water resistance

• even applicability across the surface

With these properties, the mesh acts as a kind of “soft steel.” It can be applied to natural stone, concrete, or drywall, indoors and outdoors, generally on walls. Another type of mesh is used for mosaics.

Standard weights in g/sqm are: 75, 90, 110, 125, 145, 160.

Fiberglass mesh is applied to the back of natural stone tiles using resins. Resins are usually divided into 3 categories:

• polyester resins – the most commonly used and cheapest

• vinyl ester resins – highly resistant to corrosive agents and with lower viscosity (more flexible); used mainly in marine and industrial projects

• epoxy resins – with exceptional mechanical strength, forming the strongest bond for reinforcement, and dimensionally stable. Requires precise mixing.

In short, combining fiberglass mesh with epoxy resin gives a strong, long-lasting reinforcement. Once the mesh is embedded in the resin, a film forms on the stone surface that significantly affects the tiles’ adhesion to the substrate.

To address this, classic cement-based adhesives can’t be used, since they don’t provide a strong, lasting bond. If used anyway, the cladding might hold, but only for a limited time. That’s why a different type of adhesive is needed. Epoxy adhesives, made by combining 2-3 components mixed before use, have properties that create the bond needed: they have a wide range of uses, apply easily, have good chemical and mechanical resistance, and, importantly, combine well with the resin on the back of the tiles. That said, epoxy adhesives have a short working time (usually a maximum of 45 minutes) and a limited application temperature range.

Solid (paste-type) epoxy adhesives are used to bond tiles. Once the adhesive is prepared (mixed on site, right before use), it’s applied with a rubber trowel. The tile is pressed gently into the surface. If installed with joints, adhesive is applied to the joint, and residue is removed right away, before it dries, using a sponge, water, and soap. Once dry, a thinner is needed. Curing takes several hours or even days. A test run before installation helps clarify the technique and timing.

For natural stone tiles reinforced with back mesh, using epoxy adhesives is a practical solution, the only one able to give the cladding lasting durability.