EVO-STIK TECHNIK Rapid Set Flexible forms a strong bond with concrete, cement-render, concrete block-work, tile backer-boards and brickwork. This adhesive is polymer modified to give improved flexural strength, and is suitable where under-floor heating is installed. EVO-STIK TECHNIK Rapid Set Flexible can also be used to fix tiles directly to fully-braced and secured waterproof tile backer boards and is suitable for interior / exterior use, also in swimming pools and locations which are subject to persistent dampness, e.g. showers, saunas, wet rooms and bathrooms.