Decoupling membranes are laid between new tiles and the substrate or floor underneath. This prevents newly laid tiles cracking if the substrate below moves slightly - a common occurence in new homes and floors with underfloor heating systems. These membranes act as decoupling layers to absorb movements, so the tension and stress never reaches your tiles. Most of the membranes we stock are waterproof, making them ideal to use in wet rooms & bathrooms too!