What is the difference between a crack isolation membrane and a decoupling membrane?
From the TCNA handbook:
Uncoupling membrane: An uncoupling membrane is a plastic membrane system geometrically configured to provide air space between the tile and the substrate to allow independent movement between the two and limit the transfer of stresses.
From the TCNA Handbook:
Crack Isolation Membrane: Crack isolation membranes (ANSI 118.12) for thin-bed ceramic, glass, and stone installations act to isolate the tile from minor in-plane substrate cracking.
Uncoupling and crack isolation membranes have two very different purposes. An uncoupling membrane protects the installation from differential expansion/contraction between the substrate and the tile relieving almost all shear stresses.
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