By Pierre Hébert
Photos courtesy MAPEI
Large-format tiles are defined as having at least one side greater than 381 mm (15 in.). The most popular size is 305 x 610 mm (12 x 24 in.), but they are also available up to 1.5 x 3 m (5 x 10 ft). Typically, large-format, thin-body porcelain tiles are 3 to 6 mm (1/8 to ¼ in.) thick, while standard-body porcelain tiles are thicker than 7 mm (9/32 in.). A large-format, thin-body porcelain tile is a lightweight material that is produced using less material and energy. This combination makes these tiles a suitable choice for many architects and engineers who are specifying walls, floors, and façades for ‘sustainable’ construction projects by using less material for the manufacturing and therefore reducing their overall carbon footprint.
The installation of large thin-body porcelain tiles is different from standard-body porcelain tile methods. Large-format, thin-body porcelain tiles require special installation techniques to prevent breakage during and after setup. Special equipment may also be required when placing and adjusting these large tiles. It is always recommended installers check with the thin-body porcelain tile manufacturer before selecting and installing them to ensure compliance with specific project requirements.
Tighter tolerance requirements
While the permissible variation for standard-format tiles is 6 mm in 3 m (10 ft), all approved and properly prepared substrates for large-format tiles should have no more than a permissible variation of 3 mm in 3 m from the required plane, and not less than 1.5 mm in 610 mm when measured from high points in the surface with a straight edge.
However, it is necessary to check the wall is plumb in all cases, otherwise, localized patching is recommended to repair small uneven areas. If a greater repair is required, a wall can be covered with metal lathes, followed by a scratch coat, and then a topcoat to create a new flat surface (refer to Terrazzo Tile & Marble Association of Canada’s [TTMAC’s] Guide 09 30 00, “Detail 307W”). Further, a 2-m (6-ft) level and a 3-m straight edge are valuable tools to measure possible wall variations. It is important to remember, regardless of the repair, fixing walls during the installation of a binder material can be difficult. Repairs must be completed before beginning the tile installation. As for floor-surface preparation, it is recommended to always use patching materials and an installation system from the same manufacturer to ensure material compatibility.
When using large-format tiles, an important rule of thumb is: The bigger the tile format, the more an underlayment surface (on the wall and floor) must be flat.
Building codes will likely impose wind-load and seismic-resistance requirements that may vary from one region to another, and each local code further establishes its own requirements concerning the dimensions and spacing of structural elements in preparation for abnormal conditions. For large-format, thin-body tile installation and building codes, it is recommended to seek the advice of a structural engineer and/or refer to the backer board manufacturer for requirements and recommendations.
