Permanently elastic waterproofing tape based on polypropylene fabric with alkaline protection and a rubber lining. Highly elastic, it perfectly covers cracks and provides high diffusion resistance to radon. It resists different temperatures, salts, diluted acids, and alkaline waters. It is used in combination with Bekament waterproofing coatings. The BK-Tape waterproofing tape is used for the elastic and permanent closure of cracks at contact points or corners, cracks on walls and surfaces, around drainage pipes in swimming pools, cisterns, and showers, and for connecting vertical and horizontal surfaces.