Measurement boundaries and bill split of profiled-sheet composite floors (floor decking / rebar-truss decking): the steel sheet floor by horizontal projected area, the concrete above as solid slabs less the sheet volume

Topic Positioning

The bill measurement of profiled-sheet composite floors (decking for short, both profiled-sheet and rebar-truss decking) and the bill boundaries between the decking itself and the concrete, rebars and studs above it, under GB/T 50854-2024 Annexes F and E.

Core Conclusions

1) The decking itself -> Annex F "steel sheet floors", unit m2 Annex F note F.10.5: "profiled-sheet decking and rebar-truss decking list under the 'steel sheet floor' items of this annex. Where reinforced concrete is cast on steel sheet floors, the concrete and rebars list under the corresponding items of Annex E, concrete and reinforced concrete works." Table F.5.1 steel sheet floors, wall panels and roof panels (code 010605) - steel sheet floor (010605001):

• Item descriptions: 1 steel type and specification; 2 sheet model and thickness; 3 member coating (plating) requirements
• Unit: m2
• Rule: by laid horizontal projected area at design-shown dimensions, without deducting single columns, piers and holes of area 0.3 m2 or less
• Work content: 1 assembly; 2 hoisting into place; 3 installation; 4 flaw detection; 5 touch-up painting; 6 jointing and caulking Notes: (1) "laid horizontal projection", not the developed sheet area (unlike steel roof panels on slope area and steel wall panels on developed area); (2) the work content excludes concrete casting, rebars and studs - these list separately.

2) The concrete above -> Annex E "solid slabs", unit m3, deduct the sheet, allow for the profile Annex E note E.7.4 item 2 (the core boundary): "concrete slabs cast on steel sheets list under 'solid slabs'; the quantities deduct the volume occupied by the sheets and compute the concrete volume changes caused by the profile of the sheet surface." The concrete is thus not "thickness x projection" but the net solid computed on the sheet cross-section - sheet volume deducted, profile rises and falls included. Annex E note E.7.1 item 2 (general): "cast-in-place reinforced concrete members deduct no rebar, bolts, embedded parts or ducts, but deduct the structural steel of rigid skeletons."

3) Rebars -> Annex E rebar items (010506) in t Slab rebars list under the cast-in-place rebar items.

4) Studs (shear connectors) -> separate codes Annex F note F.10.10: "the mass of high-strength bolts, bearings and shear studs does not enter the steel member quantities; they list separately by kind." Studs welded at the decking ends onto steel beams thus enter neither the beams nor the sheet floor - separate items.

5) Work-stage interface (GB 50901-2013 clause 9.1.5) "The process flow of profiled-sheet or rebar-truss composite floors shall be: fabricate the sheet or truss panel -> install it -> weld the studs -> tie the rebars -> cast the concrete -> cure it." M&E and rebar work follow only after the decking and studs pass acceptance; casting follows only after M&E, rebars and temporary propping pass. This bounds stage handover acceptance and changes none of the measurement above.

Applicability Boundaries

• Applies to bill measurement of building and decoration works under GB/T 50854-2024.
• Profiled-sheet and rebar-truss decking both take Annex F "steel sheet floors" - no separate items by deck type.
• Unlike steel roof panels (slope area) and wall panels (developed area) - never mix.
• The concrete and rebars above the sheet must list from Annex E, never squeezed into the sheet floor's all-in rate.
• Quota consumption bases may differ from the bill basis - check separately when pricing; the work-stage interface affects acceptance and preliminaries only, not the bill measurement.

Further Reading

• GB/T 50854-2024 quantity take-off standard for building and decoration works, Annex F structural steelworks: table F.5.1 (010605); notes F.10.5 and F.10.10.
• The same standard, Annex E concrete and reinforced concrete works: note E.7.1 (general) and E.7.4 (beams and slabs, item 2).
• GB 50901-2013 Code for Construction of Steel-Concrete Composite Structures, clause 9.1.5 (composite floor process flow and stage handover).