Today's Hot Tile Topic! Rectangular Tile Considerations...

Hello everyone!  So today I want to talk about something that I am continually being asked about; rectangular tile, and the installation practices that it involves!  Luckily, RBC put out a flyer on this earlier last year.  But considering how many inquiries I've had on the topic lately it seems like an appropriate time to review it. :)

Please read on below for the information found in RBC's flyer from last year:

Casa Dolce Casa, Velvet, Ecru done in a 33% offset



With the popular trend of rectangular tiles comes a need to review the factors that may affect installation.  Rectangular tiles can present unique challenges, specifically regarding lippage, when running bond patterns are used.

As defined by ANSI (American National Standards Institute) standard A108.20, Section 4.3.7; "Lippage refers to differences in elevation between edges of adjacent tile modules." ANSI A137.1 defines acceptable edge warpage in terms of a percentage of the tile's edge length, and also sets a maximum warpage amount in millimeters that cannot be exceeded, regardless of tile size.  This maximum value serves as a "cap", so that allowable warpage does not exceed a reasonable amount, even for the largest tiles.  Because allowable warpage is the lesser of the allowable percentage or maximum cap, the allowable warpage for a smaller tile is generally limited by the percentage criteria and is well below the maximum cap.  For example, a 6" rectified porcelain tile's maximum allowalbe warpage, based on the allowable edge warpage percentage criteria, is 0.6mm, while a 24" calibrated tile's maximum allowable warpage "caps out" at 1.3mm, or nearly 1/16".  Therefore, patterns and grout joint accommodations that work well with smaller tiles would not work with larger tiles exhibiting the maximum allowable warpage.  Such tiles that are just barely within ANSI tolderances are not generally recommended for offset patterns and can be highly problematic when installed with a 50% offset and a narrow grout joint.

When offset or modular patterns are desired, strong considereation should be given to the amount of offset.  For large tiles exhibiting the maximum allowable warpage, 50% offsets can exhibit lippage.  To address this on a practical basis, some manufacturers recommend against any patterns with offsets in excess of 33%.  If the tile being used has any edge larger than 18 inches they often suggest offsets of only 25%.  When considering large tiles and offsets greater than 33%, consumers are encouraged to consult with their contractor for specific recommendations.