What is BS 8102 and what are the waterproofing grades?

BS 8102:2022 is the UK code of practice for protection of below-ground structures against water from the ground. It defines three types of waterproofing protection: Type A (barrier protection — tanking), Type B (structurally integral protection — waterproof concrete), and Type C (drained protection — cavity drain systems). It also defines performance grades: Grade 1 (basic utility — some damp acceptable), Grade 2 (better utility — no water penetration but damp tolerable), and Grade 3 (habitable — dry environment, suitable for offices and living spaces). Most commercial basements require Grade 2 or 3, and BS 8102 recommends combining two or more types for critical applications.