Due to the extensive range of variables inherent to tile installation – tile types, setting materials, underlayments and substrates – Ragno USA stipulates the installation recommendations published in the TCNA (Tile Council of North America) Handbook for Ceramic Tile Installations as recognized industry guidelines for proper installation techniques. 

When choosing setting materials and grouts it is best to maintain a monolithic system, i.e. choosing all materials from one manufacturer.  All reputable installation systems manufacturers will have a technical support team to assist with questions related to these choices. 

A tile’s shade (dye lot) refers to the coloration and reflectivity of a tile. A tile’s caliber refers to its facial dimension (size) and is measured with a tool called a caliper (often the terms are confused). Ragno carefully selects its tile and indicates on every box the particular shade (dye lot) and caliber to offer customers consistency throughout an installation. Since natural materials are used in both the body and glazes of the tile, slight variations in shade and caliber are normally inherent from one production run to the next. Typically, Ragno shades (dye lots) are indicated by either an alpha/numeric combination or a three or four-digit numeral (i.e. A16, 3408, 250, etc.) while caliber sizes are normally shown as 07, 08, 09, 00, 01, 02, etc.

It is important to purchase tile that has the same shade (dye lot) and caliber, if at all possible, to ensure a pleasing aesthetic appearance as well as consistent grout joints. Using different caliber sizes result in a variation in grout joint widths, exaggerated as the size of the tile increases.  Normally, with Ragno products, two adjacent calibers (i.e. 07 with 08 or 08 with 09 - not 07 with 09) can be used in an installation if the installer is aware of the variation before the installation is begun because the slight difference can be adjusted within the grout joint. It is generally not acceptable to begin an installation with one size and abruptly change to another at some point.

Both Frost Resistance and Coefficient of Friction are criteria that must be considered when selecting tile that will be installed horizontally outdoors in freeze-thaw areas or in areas with similar environments such as walk-in freezers.   

Frost resistance is determined by the water absorption rating of a tile.  To be recognized as porcelain, a tile must be impervious with < 0.5% water absorption.  This results in a frost resistant body capable of withstanding the rigors presented by freeze-thaw conditions. 

The second factor to note when selecting a tile for outdoor usage is Coefficient of Friction, i.e. how slip-resistant is the tile?  The ADA (Americans with Disabilities Act) recommendation for slip-resistant accessible routes is a Wet COF >0.6 (> 0.8 for ramps). 

So, for freeze-thaw areas, choose Porcelain tile with a Wet Coefficient of Friction>0.6and verify that any trims selected meet the same criteria.

These combined guidelines are critical when selecting tile for exterior horizontal installations.  For vertical exterior installations, Frost Resistance is the primary factor.