At least two layers are required, regardless of whether the floor or wall is being waterproofed. One of ALPOL waterproofing products can be used for bathroom insulation, namely: ALPOL AH 751 one-component waterproofing membrane, ALPOL AH 752 two-component sealing mortar or ALPOL AH 753 waterproof mortar can be used. ALPOL AH 751 waterproofing membrane is a ready-to-use semi-liquid compound, which has to be stirred thoroughly before use. Apply the first coat of the membrane with a brush or a paintbrush, trying to rub the compound into the substrate. Apply the next coat after the previous one is dry, i.e. after around 3 hours. Each coat should dry all over its entire area. Other coats can be applied the same way or using steel float, spreading the compound perpendicularly to the previous coat. A stainless steel 4 mm notched trowel is recommended. Total thickness of wet coat should be around 2 mm, and no less than 1 mm after it dries out.