QUESTIONWhat is allowable lippage between a 13x13 inch tile and a mosaic - We are installing on walls -13x13 porcelain tiles on a 45degree angle with a 1 ft accent band 4'6"high(1"X1"mosaics)on a 12"X12" mesh and finishing with a 3X13 bullnose, What is the allowable lippage between mosaics & 13"x13".
ANSWERANSWER - There isn't a clear standard for what is allowable maximum lippage between a 13 x13 inch tile and mosaics, but I would expect it to be 1/16". For 1x1 inch tiles it is 1/32" plus allowable inherent warpage per ANSI A137.1, which is 1% of 1" (1/100 of an inch). For 13x13 depending on whether it is regular or rectified porcelain or a pressed floor tile it is 1/32" allowable lippage for 1/8" to 1/4" wide grout joints or 1/16" allowable lippage for 1/4" or wider great joints plus allowable inherent warpage per ANSI A137.1, which is more or less 1/16". From a standard of care point of view actual measurable lippage should be no more than 1/32" to 1/16" unless the tile or stone is intentionally very irregular, and then it should be more.
If the grout joints are too tight they will accentuate the lippage and if the wall lighting is in the wrong position that will further accentuate the lippage. On the other hand, to minimize lippage accentuation, grout joints should be wider and lighting should be properly positioned.