Installing Large Format Tiles

Installing Large Format Tiles

Large format tiles cover a larger area and require fewer gaps and breaks such as grout lines and expansion joints. They create the illusion of a monolithic, seamless finish which is highly appreciated by many architects and clients.

There are various sizes and thicknesses of large format tiles currently available on the market, with some formats reaching dimensions of up to 3.2 m x 1.6 m and slim tiles with thicknesses ranging from as low as 3 mm up to 12 mm.

Large format tiles may be installed on all substrates including concrete, cementitious screeds and screeds made from special binders such as TOPCEM and TOPCEM PRONTO. They may also be installed on internal substrates waterproofed with cementitious products such as MAPELASTIC SMART, or synthetic resin-based products such as MAPELASTIC AQUADEFENSE.

The substrate should have no cracks, be dry, well cured and even, clean and flat. Since the tiles to be installed are so large and slim, flatness is a particularly important aspect of substrate preparation therefore levelling products such as ULTRAPLAN and ULTRAPLAN MAXI may be used prior to installation.

Choosing the right adhesive is fundamental in guaranteeing that a tiled surface remains sound and reliable over the years. When it comes to large format tiles, EN 12004 strongly recommends the use of class S2, highly deformable adhesives such as ULTRALITE S2.

According to EN 12004, a class C2 cementitious adhesive with improved characteristics is required to install all porcelain tiles due to the incredibly low absorption rate. When working in hot climates, EN 12004 recommends the use of class E adhesives (adhesives with extended open time). It is more appropriate to use a reactive adhesive, or class R2 such as KERALASTIC T to install large format tiles on some substrates including wood, PVC, rubber, linoleum, metal surfaces and resin surfaces.

The adhesive must always be applied using the double-buttering technique, where adhesive is applied on both the substrate and on the back of the tile. Once installed, tiles must be tapped to prevent the formation of air pockets between the tile and the substrate.

Large format tiles must be installed with grout lines at least 2mm wide. The width of grout lines should be established during the design phase and is based mainly on the type of substrate material, the size and type of tile and the area of use (wall or floor, internal or external), with the width increasing according to the area of use and the stresses expected when in service. The grout lines may be filled with cementitious grout, such as ULTRACOLOR PLUS, or with epoxy grout, such as KERAPOXY, KERAPOXY DESIGN or KERAPOXY CQ.

Joints should be reflected in the tile layout. Perimeter deformation joints and distribution joints must be created every 25 m2 on stable surfaces, while on substrates subject to movement or flexure joints should be approximately 12 m2.

Expansion joints in internal walls and floors may be filled using MAPESIL AC. For external applications, MAPESIL AC may also be used for floor tiles, while MAPESIL LM should be used for wall tiles.