Parapet inner-face plastering: interior or exterior wall items? Attribution method, regional norm precedents, and pricing points

Topic Positioning

Norm attribution for pricing parapet inner-face plastering: exterior items, or interior items (with or without factors), the BOQ-level caliber, regional precedents, and compilation practice.

Core Conclusions

1. No national answer; the dispute is at norm-application level, not BOQ itemization: GB/T 50854-2024 Annex M lists "wall/column general plaster" and "miscellaneous plaster" without interior/exterior distinction. Attribution per the local current norm notes.
2. Mainstream caliber: treat as exterior (merge into exterior plaster). Rationale: though on the roof's inner side, parapets face outdoor conditions and high-level work; inputs are closer to exterior walls.
3. Regional precedents (verbatim):
   • Shaanxi 2024 draft, Chapter 12 notes, item 4: "Parapets without drip-nose bricks: interior items with labor and machinery x 1.10; with drip-nose bricks: x 1.30; the outer face merges into exterior computation." Same chapter rules: "Parapet (incl. drip nose, projecting brick) inner faces, balcony balustrade inner faces (no deduction of lattice openings) and outer faces by structural design-shown dimensions by area."
   • Beijing DB11/T 2382-2024 Section 4.13 (4.13.1-4.13.28) verified clause-by-clause — no parapet clause; apply the general caliber (e.g., 4.13.21: wall plaster/screed by design-shown area, no deduction for skirting, picture rails, wall-member joints, or single holes <= 0.30 m2; attached columns/beams/piers/chimney flues merge into the wall). Industry sources claim earlier Beijing norms said "parapet inner face merges into exterior" (unverified); by convention, Beijing projects are safest priced on the exterior caliber.
4. Other-region Q&A leads (unverified, indicative only): Hubei — parapet inner plaster as exterior plaster x 1.2; Shandong — merged into exterior items.
5. Price-gap logic (why attribution matters): per TB/T 10831-2024 Vol. 10 general plaster, interior (14+6) labor 127.50 yuan/10m2 vs exterior (14+6) 207.50 yuan/10m2 — about 63% apart; the difference is set by local norm measurement — not transferable.
6. Compilation points: check local norm notes and interpretations first — explicit text governs; otherwise merge into exterior by convention and record in the compilation notes; one BOQ item must use one caliber (no mixed items; describe "parapet inner face"); adjacent items — coping plaster usually as line/miscellaneous items (Shaanxi: "lines apply to door/window heads, cantilevers, strings, copings..."; single width > 500mm uses floor/wall/ceiling items); contracts and tender documents govern; absent agreement the price gap is an audit focus.

Applicable Boundaries

• Applies to interior/exterior attribution disputes in pricing wall/column plaster (BOQ code 011201); the BOQ itself does not split.
• Regional clauses are not transferable: use the project's local current norm; the Shaanxi clause is a 2024 draft — verify the published edition.
• Hubei/Shandong and "general convention" leads come from industry Q&A — verify against original text before relying on them.
• The railway figures illustrate the price gap only — not a basis for building pricing.
• Contracts, tender documents, and local pricing interpretations govern.

Further Reading

• GB/T 50854-2024 Annex M: M.1.1 (011201), M.8.3.
• DB11/T 2382-2024 Section 4.13 (4.13.21, 4.13.24).
• Shaanxi 2024 draft Chapter 12 note 4 and plaster rules item 4.
• TB/T 10831-2024 Vol. 10 FY-1346 (interior 14+6), FY-1347 (exterior 14+6).
• Industry Q&A leads (Hubei/Shandong) — verify locally before use.