A crack isolation membrane is a thin membrane that isolates thin-set ceramic tile and dimensional stone from minor in-plane substrate cracking. The crack isolation membrane can be trowel applied, a liquid or a sheet membrane, that the tile or dimensional stone is direct bonded to. Please see ANSI A118.12 for additional guidelines. Current crack isolation membranes from TexRite; UniFlex trowel applied, HydroRite liquid membrane, and the NAC products line which are all sheet type membranes.
Whenever cracks in substrates need to be isolated from the finished floor. Especially when installing an intricate patterned floor or expensive dimensional stone.
No. Expansion joints are designed to handle building movement both horizontally and vertically. All expansion joints must be carried through the tile or stone finish. See Tile Council of North America Handbook EJ171 regarding movement joints.
The first step is to always verify the compatibility of cement-based thin-sets to the crack isolation membrane that has been specified or installed on the job. CAUTION: There are numerous membranes available in the marketplace today that are not compatible with tile or dimensional stone installations. Usage of crack isolation membranes meeting ANSI A118.12 insures compatibility with ceramic tile setting materials. If you are unsure, verify compatibility with the membrane manufacturer before installing tile or dimensional stone. TexRite Ceramabond, MultiPurpose, TotalContact, CeramaFlex, UniFlex and EpoxyPlus 2002 are all compatible with many of the membranes currently available.
The float material should always be installed first to allow placement of the crack isolation membrane as close as possible to the finish tile surface to stop any cracks from migrating into the tile. If installed properly, any float work will stay bonded to the substrate even though it might crack; in that case, the crack isolation membrane is on top of the float where it will isolate the crack from the tile.
Yes. TexRite HydroRite or UniFlex can be used on exterior applications in addition to the NAC Products membranes. Caution: Exterior patios typically do not have a moisture barrier underneath therefore make sure there is functional drainage of the surrounding soil to reduce the possibility of hydrostatic pressure causing a membrane bonding failure.