What’s an uncoupling membrane?
Also called “decoupling membranes,“these products are sold in rolls and are installed over subfloors before the ceramic tile is set. They help isolate the tile from a subfloor that expands, contracts or flexes, reducing the risk of cracks and loose tiles. The membranes are a thin, semirigid plastic. Some are solid sheets that act as a moisture barrier, while others, such as Laticrete’s STRATA_MAT, have moisture vents to speed curing.
The membranes have fleece or mesh on their underside that bonds to the subfloor with thinset. On the topside are grids or profiles, which differ among manufacturers, and some can accept and hold tubing or electric cables to heat the floor. Examples include DITRA-HEAT from Schluter and HeatMatrix from SunTouch, a
Watts brand. Schluter also offers DITRA-HEAT-DUO, a membrane that has additional bonding fleece to provide a thermal break and some sound control.