#MAPEITechTip: When installing Large Format Tile (LFT)/Thin Porcelain Tile (TPT)—what are some key factors to keep in mind?

Innovations in lightweight Thin Porcelain Tile (TPT) technology have changed the face of the construction industry—significantly reducing the overall dead load weight of a building without compromising strength and durability. It is important to remember that TPT’s are relatively new to the marketplace, being markedly different to ‘standard body tiles’ due both to the larger format (up to 3’ x 10’ [1M x 3M] and also decreased thickness (1/8” to 1/4”  [3mm to 6mm]).  This has required all key players in the installation process to re-think how we install these tiles—from the surface preparation, mortar selection, tools needed and application method. Due to the decreased thickness and increase in format size, it is critical to establish a baseline when installing these tiles on the floor, using the TCNA ‘Service Rating’ (based on the ASTM C627; Robinson test method)—a series of baselines have been established and published in the most current TCNA Handbook as ‘Service Requirements’, EXTRA HEAVY, HEAVY, MODERATE, LIGHT & RESIDENTIAL. (In a future blog, there will be a more in depth discussion of the ASTM C627 test method)

In addition to establishing the ‘service rating’, there are four key areas to address during installation:
 
1. Surface preparation:  The substrates should have no more than a permissible variation of 1/8 inch in 10 feet (3 mm in 3,05 m) from the required plane; nor more than 1/16 inch in 24 inches (2 mm in 60 cm) measured from high points on surface with a straight edge. Floor flatness is best achieved using one of MAPEI’s family of self-leveling underlayments & primers prior to tile placement.

2. Proper MAPEI mortar selection: Once you have ensured a flat surface, it is important to choose a mortar that will give you maximum coverage to both the back of the tile and substrate, thusly ensuring a strong bond that can perform to the ‘service rating’ that installation was designed for, ie: office foyer. MAPEI has found the following mortars achieve this level performance for large format TPT:  Granirapid ® System; Kerabond/Keralastic™ System; KerabondT/Keralastic™ System Ultraflex ™ LFT™ Rapid; Ultraflex LFT; Ultraflex RS; Ultralite™ Mortar; and our newest Ultralite S2 Thin Tile Mortar (C2ES2P2) is the first mortar strategically designed to install thin tile, solving many of the challenges associated with large format thin porcelain tile. The Ultaltite S2 takes this technology to the next level by its superior transfer properties, extended open time and wet-out characteristics—optimizing coverage.

3. Proper trowel selection:  Use a trowel configuration that maximizes mortar coverage between the substrate and the tile, minimizing air pockets and voids.  Often this means using a non-traditional Euro Notch or Slant Notch trowel to achieve maximum coverage.

4. Use of a ‘lippage control system”:  Using a mechanical system with either straps or wedges to apply equal pressure on the tile, pulling it down into the mortar and locking the entire system together.  Once the mortar has dried sufficiently, typically 24 hours, the ‘lippage control system’ can be removed—with improved contact between the tile and substrate while reducing the chances of lippage.

Always consult the TPT manufacturer for the ‘service rating’, specific area of use and limitations prior to installation.  For more detailed information regarding TPT, see MAPEI’s Reference Guides for Thin Tile Installations for Walls and Thin Tile Installations for Floors and the Construction Specifier May 2015 Article, "Light and Large: Considerations for commercial thin-tile installations"