ČSN EN 12255-11

This document classifies floor gullies for domestic waste water for use inside buildings, gives guidance for places of installation and specifies requirements for the construction, design, performance and marking of factory made gullies for buildings, irrespective of the material, for use in drainage systems requiring a trap with a depth of water seal less than 50 mm (referred to as floor gullies).
NOTE - Floor gullies with a depth of water seal less than 50 mm are not covered by EN 1253-1, EN 1253-7 and 1253-8.
These products are intended to be installed where the three following conditions are met:
- space limitation will not accommodate a gully with a 50 mm water seal;
- the building does not exceed a ground-floor and three floors above;
- at least two domestic sanitary appliances are installed in addition to the gully but with only one WC on the same branch (connection pipe) or secondary or branch ventilation is installed (see EN 12056-2:2000, 4.3.2 or 4.3.4.)