QUESTION

What are industry standard allowance lippage for 18 inch square tiles? We have been told they are 1/16 of an inch, but this was based on 2011 standards. Thank you

ANSWER

ANSWER - Allowable tile lippage for ceramic tile, including porcelain tile, which is a type of ceramic tile, is based on the grout joint width and the amount of allowable warpage that the tile itself exhibits.  The ANSI A108.02 standards have not changed since 2011 in this regard.

For grout joints less than 1/4" wide the allowable lippage is 1/32" plus the inherent allowable warpage that the tile  being installed actually exhibits.   So if the tile has 1/32" of warpage then the allowable warpage is 1/16".

For grout joints 1/4" or wider the allowable lippage is 1/16" plus the inherent allowable warpage that the tile  being installed actually exhibits.   So if the tile has 1/32" of warpage then the allowable warpage is 3/32".

Inherent warpage is defined as the actual warpage exhibited in the tile being installed, as long as that warpage does not exceed the allowable warpage for that classification of tile as stated in ANSI A137.1.

It is my opinion that in some cases the allowable warpage stated in ANSI A137.1, if added to the respective allowable lippage in ANSI A108.02, would result in lippage that would be excessive and not reasonable.

The allowable lippage for natural stone is 1/32" for calibrated smooth surfaced stone tiles.  Tiles with cleft or irregular surfaces can result in significantly more lippage that could be considered reasonable for that particular type of stone.