Products : Setting : Additives : Thin-Set Mortar Admix

Thin-Set Mortar Admix

A liquid polymer designed to be used in place of water to increase performance of cement mortar beds, non-modified, thin-set mortars and cement-based grouts. It improves working characteristics and performance of cement-based mixes to boost water resistance, shock resistance and freeze-thaw capabilities for tile, stone or masonry installations. Increases performance of non-modified thin-set mortars for setting dense tile and setting over hard-to-bond surfaces. Thin-Set Mortar Admix can be used with non-modified, thin-set mortars such as, CustomBlend® Thin-Set Mortar and Uncoupling Mat Mortar. It can also be used with Saltillo Grout Mix.

  • Features & Benefits
  • Technical Documents
  • Warranty Information

Suitable Tile Types

  • Vitreous, semi-vitreous or non-vitreous tile: ceramic, mosaic, quarry, cement body tile
  • Impervious porcelain and glass tile
  • Brick and stone veneer
  • Cement-based precast terrazzo
  • Natural stone tile

Suitable Substrates

  • Concrete, mortar beds, masonry, Portland cement plaster
  • WonderBoard®, cement backerboards
  • Liquid applied waterproofing membranes such as RedGard® and Custom® 9240
  • Crack prevention sheet membranes such as Crack Buster® Pro
  • Exterior Grade Plywood (interior residential and light commercial dry areas)
  • Gypsum wallboard (interior dry areas)
  • Existing ceramic tile
  • Fully-bonded sheet vinyl flooring
  • Plastic laminates
  • Cutback adhesive (see preparation instructions)

Composition & Materials

Liquid Latex


When mixed with non-modified thin-set mortars and mortar bed mixes:

  • Improves bond strength
  • Improves freeze-thaw durability
  • Improves Flexibility

Increases performance for:

  • Installation of hard-to-bond tiles
  • Interior and exterior applications


  • Do not bond directly to hardwood, Luan plywood, particle board, parquet, cushion or sponge-back vinyl flooring, metal, fiberglass, plastic or OSB panels.
  • When setting moisture sensitive natural stone, cement or agglomerate tile use EBM-Lite® Epoxy Bonding Mortar 100% Solids or CEG-Lite® 100% Solids Commercial Epoxy Grout.
  • Do not use to install resin-backed stone use EBM-Lite® Epoxy Bonding Mortar 100% Solids, CEG-Lite® 100% Solids Commercial Epoxy Grout or contact Custom's® Technical Services for recommendations.
  • When setting glass tile larger than 6" x 6" (15 x 15 cm), contact Custom's® Technical Services for recommendations.
  • When setting dimensional stone larger than 12" x 12" (30 x 30 cm), contact Custom's® Technical Services for recommendations regarding subfloor deflection requirements.


  • 2.5 gal (9.46 L) bottle
  • Canada 2.5 gal (9.46 L) bottle

Technical Data

Applicable Standards

American National Standards Institute (ANSI) ANSI A108.5; A118.4; A118.11 of the American National Standards for the Installation of Ceramic Tile

Tile Council of North America (TCNA) TCNA Handbook for Ceramic Tile Installation, TCNA Method EJ171


Technical Data Sheet Technical Data Sheet - French Technical Data Sheet - Spanish Material Safety Data Sheet - English Material Safety Data Sheet - French

Product Warranty

Custom® Building Products warrants to the original consumer purchaser that its product shall be free from defects in material and workmanship under normal and proper usage for a period of one year following the date of original purchase. Custom's® sole liability under this warranty shall be limited to the replacement of the product. Some states, countries or territories do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you. This warranty will not extend to any product which has been modified in any way or which has not been used in accordance with Custom's® printed instructions. Custom® makes no other warranties either expressed or implied. This warranty gives you specific legal rights, and you may have other rights that vary from state to state or from one country/territory to another.  This warranty is not transferrable.

Related Products

Uncoupling Mat Mortar

View Product Details

CustomBlend® Standard Thin-Set Mortar

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Saltillo Grout Mix

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Polyblend® Sanded Grout

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