BS 8490:2025

Siphonic roof drainage systems. Guide. | Status: Current

1 Scope This British Standard provides guidance and recommendations for roof drainage systems using circular-section pipes that operate under siphonic action, including:

1. a) design parameters;
2. b) installation;
3. c) verification; and
4. d) maintenance needs of siphonic roof drainage systems conforming to the performance requirements in BS EN 12056‑3:2000, 6.2.

Guidance is also given on carrying out testing of outlets and checks of designs, for the use of specifiers and regulatory authorities. Recommendations for site drainage systems that receive flows from siphonic roof drainage systems are also covered.