PROFLEX™ CISM 40 Crack Isolation Membrane

Proflex CISM 40 is a 40 mil crack isolation membrane made up of 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 CISM 40 is designed for full coverage crack suppression. PROFLEX CISM 40 crack isolation membrane 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 and to reduce sound transmission. Other applications also may be suitable. 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.



  • Easy and fast to install with standard tools
  • Ready for tiling immediately after installation
  • Crack and joint isolation up to 3/8″
  • Crack Suppression
  • Sound Control
  • Moisture Vapor Protection up to 5# per 1000 sq.ft/24 hr
  • *CaCl2 Test (see installation instructions)

Suitable Surfaces

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

Coverages, Packaging

  • 195 sq.ft. per roll
  • 3′ x 65′ roll boxed

Companion Products

Data Sheets

Requires Adobe Reader Data and Installation Guidelines

Requires Adobe Reader Sound Test (IIC)

Requires Adobe Reader Sound Test (STC)

Requires Adobe Reader Flame Spread Rating (Tile)

Download PDF

Requires Adobe Reader Flame Spread Rating (Wood)

Download PDF

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.