BOQ attribution of rainwater outlets (roof drains): under the sanitary-fixtures chapter's "water supply and drainage attachments", not "heating/water-supply equipment" (GB/T 50856-2024 Appendix K)

Topic Positioning

Do rainwater outlets belong to "sanitary fixtures" or "equipment" in BOQs and assembly? This card gives the attribution rule per the clauses and table structure of GB/T 50856-2024 Appendix K, plus independent/non-independent listing calibers and cross-discipline differences.

Core Conclusions

1. Not "equipment". GB/T 50856-2024 Table K.5.1 "heating and water-supply equipment" (031005) is organized by packaged equipment and vessels (booster sets, heat exchangers, water treatment) and contains no pipe-end fittings like outlets; the outlet (cast iron, siphonic, etc.) is a single pipe-end fitting without packaged-equipment nature. Terminology corroborates: GB 50015-2019 Clause 2.1.88 defines the outlet as "a device introducing roof rainwater into the riser" — a port component, not a packaged unit or vessel.
2. Under the sanitary-fixtures chapter as "water supply and drainage attachments". Table K.3.1 note (Clause K.9.8) Item 2, verbatim: "Water supply and drainage attachments mean independently installed taps, floor drains, floor cleanouts, etc.; non-independently installed such attachments shall be included in the work content of the related fixtures or equipment." Outlets are pipe-end attachments like floor drains and cleanouts, within the "etc."; hence two listing calibers:
   • Independent (separately supplied/installed) -> list under "attachments", price independently;
   • Non-independent (with siphonic/roof drainage systems) -> merge into the related items, not listed again.
3. Attachment-follows-principle (same note Item 1): "The work content of all fixtures includes supply attachments — taps, flexible hoses, valves, flush pipes, spray heads — and drainage accessories — traps, waste fittings, drains — and the connecting pipes provided." Whether listed depends on "independent installation", not the name.
4. Local and industry corroboration:
   • SJG 77-2020 Clause 6.3.6: "The siphonic system should include installation and commissioning of siphonic pipes, siphonic outlets, and pipe accessories." — outlets follow the system, not equipment.
   • DB11/T 2382-2024 Appendix C: outlets as independent sub-items by count, e.g., C10-6-81 cast-iron outlet DN100, work content including hole reserve/blocking, haulage, checking, installation, water test.
   • TB/T 10831-2024 Vol. 10 places outlets in the civil "roof drainage" section's gravity series (FY-874-887, work content "install plastic downcomers and fittings; install outlets and clamps"), listed with the pipes.
5. Practice: the same outlet may be listed as an "attachment" under installation and merged into the drainage system under roofing/civil — fix the trade attribution per contract/tender before budgeting; never list it in both.

Applicable Boundaries

• Applies to general-installation (water/sewer/heating/gas) BOQs under GB/T 50856-2024; analogous attachments (taps, floor drains, cleanouts) follow the same test.
• "Independent" is judged by supply/install interface (whether with the system/fixtures), not by name; non-independent attachments are already in the host items.
• Disciplines (general installation / building / railway) and local lists may organize outlets differently; combine with the contract's trade division and current local standards.
• Not applicable to packaged rainwater harvesting/utilization system equipment with true equipment nature.

Further Reading

• GB/T 50856-2024 Appendix K: Table K.3.1 (031003) and note K.9.8 (Items 1-2), Table K.5.1 (031005);
• GB 50015-2019 Clause 2.1.88 (term);
• DB11/T 2382-2024 Appendix C: C10-6-81 etc., Table C.10.53-7 "rainwater outlet installation";
• SJG 77-2020 Clause 6.3.6 (siphonic system composition);
• TB/T 10831-2024 Vol. 10, Chapter 1 civil "roof drainage", FY-874-FY-887.