MSI (Thick Bed Mortar)

PROFLEX™ MSI is an installation system for installing tile and stone finish surfaces to a variety of substrates. The system uses PROFLEX™ elastomeric Crack Isolation membranes, or our Hydra-Seal crack isolation and waterproofing along with a high strength ANSI 118.11 thinset style mortar (PART 1) and a Reinforced Portland cement based thick bed mortar mix (PART 2). These components work together to ensure a superior bond of tile and stone finish surfaces unmatched by other manufacturers.



PROFLEX™ MSI is a system of products to be used for installing large format tile and stone. It is specially formulated to control shrinkage of a thick bed mortar. This system is designed to assist installers that are installing larger tile and stone as well as un-gagged stone, slate , marble, and granite (not water sensitive stones). Designed to go up to 4” over the Proflex membranes. The system can be applied to floors, countertops, and shower floors.


  • Consistent Performance
  • Both Part 1 and 2 mix with water
  • High Strength bond for large format Tile and Stone installations
  • Portland Cement Based Products
  • Limited 15 year system warranty
  • Meets and Exceeds ANSI A118.11, A108.1A, A108.1B
    *CaCl Test (see installation instructions)

Suitable Surfaces

  • Concrete Substrates to be structurally sound, dry and free from grease, oil, dirt, dust, and other foreign matter such as curing agents and other “bond breaking” material.
  • Use a minimum 5/8” premium grade plywood over subfloor; All wooden flooring underlayment’s to be placed over 16” on center joists with a total thickness of 1 1/4” of the wooden substrate.

Coverages, Packaging

  • MSI PART 1 – An ANSI A118.11 multi purpose, Portland cement based, polymer modified mortar.
  • MSI PART 2 – Portland cement based thick-bed mortar mix with various sized aggregates and specially designed fiber reinforcement. Working Time: 60 minutes Coverage: One (1) 50# bag of mortar will yield 7sq.ft at 1” thickness. Do not exceed 4” of thickness with this product.

Data Sheets

Requires Adobe Reader Data / Installation Guidelines

Requires Adobe Reader Material Safety Data Sheet n/a

Requires Adobe Reader Bronze 5 Year Warranty 

Requires Adobe Reader Silver 15 Year Warranty 

Requires Adobe Reader Gold Limited Lifetime Warranty 

Warranty based on the system of materials used to install finish flooring products.
Please refer to our full warranty information for specific terms and conditions.