If ceramic tiles, porcelain, or stone coverings are installed on cement subfloors, it is highly recommended to install a crack isolation membrane to waterproof the floor coverings and protect them from the movement of the cement floor.

What is a crack isolation membrane?

A crack isolation membrane is a thin membrane that isolates ceramic tiles, porcelain, stone coverings from minor in-plane substrate cracking and provides floor covering waterproofing.

Types of Crack Isolation Membranes

  • sheet crack isolation membrane
  • liquid or so called trowel-applied crack isolation membrane

Benefits of Crack Isolation Membranes

  • Protect ceramic tile installation from cracking
  • Provide waterproofing for ceramic tiles, stone, porcelain and natural stone floor coverings
  • Reduce inter-floor noise
  • Inhibits mold and mildew growth
  • Ceramic tiles, stone, porcelain and natural stone ca be directly installed onto the crack insulation membrane
  • Quick and easy to apply if liquid
  • Safe and non-flammable
  • Rated for extra heavy service

Typical Applications for Crack Isolation Membranes

  • Kitchens
  • Countertops
  • Bathrooms
  • Laundry Rooms
  • Mud Rooms
  • Entrance Hall
  • Showers
  • Bathtub Surrounds

Required Tools and Materials

Steps for Installing Liquid Isolation Membrane

  • Vaccum or wipe clean the cement floor thoroughly
  • Remove all paint, efflorescence, concrete sealers, and any material that may prevent adhesion
  • Apply liquid latex with brush, roller or trowel in the coves, corners and drain areas
  • Enbed a layer of reinforcing fabric while the coat of liquid latex is still wet and apply a second coat of liquid crack isolation membrane
  • Allow liquid membrane to dry in coves, corners and drain areas
  • Apply a coat of liquid crack isolation membrane over the entire floor
  • Embed a layer of reinforcing fabric while the coat of liquid latex is still wet and apply another coat of liquid crack isolation membrane
  • Bleed the liquid through the fabric and overlap the fabric at the seams by 2″
  • If more crack isolation is required, apply a second layer of fabric
  • Once the second layer of fabric is completely embedded apply a final coat of liquid crack isolation membrane and let it dry

Steps for Installing Sheet Isolation Membrane

  • Vaccum or wipe clean the cement floor thoroughly
  • Remove all paint, efflorescence, concrete sealers, and any material that may prevent adhesion
  • Apply thin-set mortar with a 1/4″ notched trowel
  • Roll-out the membrane and cut its edges with a utility knife
  • Smooth out the membrane with a heavy floor roller
  • Start rolling from the center of the membrane to allow air trapped underneath to escape
  • Continue with the next membrane
  • Allow mortar or bonding material to cure per manufacturer’s instructions before you install the tiles

Tips for Installing Crack Isolation Membranes

  • Some isolation membranes require a special bonding material instead of thinset mortar
  • Do not leave any seams between the isolation membrane sheets
  • Do not apply crack isolation membranes over expansion joints – all expansion joints must be carried through the ceramic tile or stone finish
  • If the floor is floating, the float material should be installed first and then the crack isolation membrane
  • Crack isolation membranes must be installed as close as possible to the finish tile surface to stop any cracks from migrating into the tile
  • Always verify the compatibility of cement-based thin-sets to the crack isolation membrane that has been specified or installed on the job
  • Not recommended for use on concrete floors where hydrostatic head pressure is present
  • Areas such as showers must have slopes of 1/4″ per foot towards the drain

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