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How to Install Liquid and Sheet Crack Isolation Membranes

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

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