Crack Isolation Membranes


Peel and Stick 40 mil. Crack Isolation Membrane

PROFLEX® SIM 40 is a 40 mil composite underlayment consisting of a rubberized membrane laminated to a high strength reinforcing fabric on the face and a siliconized release sheet on the adhesive side. Proflex SIM 40 is designed for full coverage crack suppression. PROFLEX® SIM 40 is specially designed to be used under approved thinsets, mortars, and adhesives for interior and exterior applications of ceramic tile, stone, and brick, and for interior applications of wood flooring to eliminate the transmission of cracks through finish flooring. To eliminate cracks in finished floor work, the product should be applied to the entire substrate prior to the installation of the finished flooring for crack suppression.


  • 40 mil. thickness (0.040 of 1”)
  • Crack Suppression
  • Moisture Vapor Barrier 5lb./1000sq.ft (24hr CaCl test)
  • Crack and joint isolation up to 3/8″
  • Easy and fast to install with standard tools
  • Ready for tiling immediately after installation

225 sq. ft. per Roll, * SIM-40 requires an ANSI A118.11 thinset.

Concrete (Poured, Prestressed, Precast), Cured (Mortar Beds, Self Leveling Compounds, Gypcrete), Concrete Backerboards, Wood (Exterior Grade Plywood, Hardwood, Tongue and Groove)

1 Roll per Box, 24 Boxes per Pallet

Available docs (click to download)

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