Custom Building Products Natural Stone and Large Tile Premium Mortar is a premium quality, polymer-modified mortar for any size natural stone or large format ceramic or porcelain tile 15 in. (38 cm) or larger on one or more sides. This mortar can also be used to install clay pavers or for medium bed applications. With a non-slumping formula that reduces the chance for lippage and promotes level tile installations, the mortar can be applied for horizontal applications as thick as 3/4 in. (19 mm) or for thin bed applications to 1/4 in. (6 mm).