Confidence HighUpdated 2026-09-25

Waterproof protective layer (protection over membrane waterproofing): quantity calculation, BOQ itemization, and norm application — roof, floor, and foundation positions

Protective layers are computed by design-shown area (m2) (DB11/T 2382-2024, 4.10.27): roofs follow the roofing caliber (flat roofs by horizontal projection, sloped by slope area; upturns and gutters merge, 4.10.20); floors do not deduct partition walls and single <= 0.30 m2 columns/piers/holes, upturns <= 300mm merge (4.10.25); > 300mm executes wall waterproofing (4.10.16); foundation upturned beams merge by developed area (4.10.26). In BOQs, roof protection uses "rigid roofing layer" with its function described (GB/T 50854-2024, J.6.5); foundation/floor fine-stone concrete protection uses "fine-stone concrete floor" (J.6.11); reinforcement mesh listed separately (J.6.12); Beijing lists protective-layer items separately (2021: 9-265~267; 2024: A-9-264~267), all in m2.

Applicable Codes

DB11/T 2382-2024 · Standard for Construction Consumption of Construction Works (Beijing) 第4.10节（屋面及防水工程）
GB/T 50854-2024 · Standard for measurement of building construction and fitting out works App. J（第J.6.5、J.6.11、J.6.12条、Table J.2.1、Table J.4.1）、App. L（Table L.1.1）

Topic Positioning

Quantity calculation, BOQ itemization, and norm application for protective layers over (membrane) waterproofing — a reusable three-layer "takeoff -> itemization -> norm application" rule set covering roof, floor, and foundation positions.

Core Conclusions

1. Takeoff: by design-shown area (m2), not volume Beijing DB11/T 2382-2024, 4.10.27: "Waterproof protective layers and joint sealing: (1) protective layers by design-shown area; (2) sealing by design-shown length." By position:

Roof (4.10.20): sloped roofs by slope area, flat (incl. sloping-to-drain) by horizontal projection; areas of roof chimneys, vent bases, ducts, small skylights, and valley gutters are not deducted, nor are upturns added; upturns at parapets, expansion joints, and skylights merge into the roof quantity; valleys, eaves gutters, cantilevers, and canopies merge by developed area.
Floor (4.10.25): by design-shown area, no deduction for partition walls or single columns, piers, chimneys, holes <= 0.30 m2; upturns <= 300mm merge into the floor; > 300mm executes wall waterproofing (4.10.16).
Foundation (4.10.26): by design-shown area, upturned (counter) beams merge by developed area; pile-head waterproofing by count; waterproof fabric by area; waterstops by length.

2. Itemization: the protective layer is an independent BOQ item, not merged into waterproofing GB/T 50854-2024:

J.6.5: roofing screeds, protective layers, and rigid isolation layers are coded as "rigid roofing layer" with the function described in characteristics; roof insulation formed slopes and integrated waterproof-insulation roofs use Annex K "insulated roofs".
J.6.11: wall waterproofing screeds use Annex M "vertical mortar screed"; floor and foundation screeds use Annex L screed items; foundation fine-stone concrete protection uses Annex L "fine-stone concrete floor".
J.6.12: factory mesh and wire mesh use Annex E "reinforcement mesh"/"wire mesh"; other reinforcement uses "reinforcement in rigid roofing layer".

3. Norm application: Beijing lists "waterproof protective layer" items separately, unit m2

2021: 9-265 mortar DS pea-gravel concrete, 9-266 mortar DS polyethylene foam, 9-267 mortar DS polystyrene board;
Current 2024: A-9-264~267, split into mortar / pea-gravel concrete / polyethylene foam / polystyrene board types.

4. Common errors

Protection and waterproofing are two independent items — same drawing scope but never mutually inclusive;
Floor upturns > 300mm belong to "wall waterproofing" — the protection there itemizes by wall position;
Mesh/wire in the protection itemizes separately (factory mesh via Annex E, other via "reinforcement in rigid roofing layer").

Applicable Boundaries

Takeoff and norm calibers per Beijing DB11/T 2382-2024; non-Beijing follows local standards; itemization per the national GB/T 50854-2024.
Protective-layer type, thickness, upturn heights per drawings; 300mm is the floor-vs-wall item boundary.
BOQ and consumption calibers are two records: roof waterproofing under Table J.2.1, floor waterproofing under J.4.1, fine-stone protection under L.1.1 — different deduction/merge rules, do not mix.
Insulation-formed slopes and integrated waterproof-insulation roofs do not use "rigid roofing layer" — Annex K applies.

Keywords

防水保护层
涂膜防水保护层
防水保护层工程量
屋面刚性层
细石混凝土保护层
防水保护层定额
GB/T 50854-2024
DB11/T 2382-2024

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Setting and measuring the height of waterproof upturns (turned-up edges): design first, codes as the floor (GB 55030-2022 and GB 55038-2025 mandatory positions and conflicts with local standards), the datum of the finished floor level, and the 300 mm split between floor and wall waterproofing items
Upturn height follows "design first - where unstated, take the code minimum - where in conflict with a fully mandatory national code, the national code prevails", measured from the finished floor level (topping / finish face), not the structural face: shower-zone walls turned up not less than 2000 mm and not lower than the shower head, walls at wash-basins and other water points not less than 1200 mm, and flashing at other wall parts not less than 250 mm (GB 55030-2022 clause 4.6.4, fully mandatory; GB 55038-2025 clause 4.1.9 same position, adding a floor drainage slope of not less than 1% and damp-proofing of the remaining walls and ceiling). Where a local standard is lower (e.g. DB/T 29-35-2017 clause 10.3.5 with 1800/1100/300 mm), set 2000/1200/250 mm per the mandatory national code; stricter parts of the local standard may be retained. Measurement per GB/T 50854-2024 Annex J clause J.6.8: where the floor waterproof upturn exceeds 300 mm it is listed under the wall waterproofing code (010903); the turned-up part within 300 mm merges into the floor waterproofing quantities (010904); upturn quantity = developed upturn length (perimeter at the wall junction) x upturn height.

Waterproof protective layer (protection over membrane waterproofing): quantity calculation, BOQ itemization, and norm application — roof, floor, and foundation positions

Applicable Codes

Topic Positioning

Core Conclusions

Applicable Boundaries

Further Reading

Keywords

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Cited By

Setting and measuring the height of waterproof upturns (turned-up edges): design first, codes as the floor (GB 55030-2022 and GB 55038-2025 mandatory positions and conflicts with local standards), the datum of the finished floor level, and the 300 mm split between floor and wall waterproofing items