Sorting out the measurement of underfloor heating coils (floor radiant heating pipes): the bill measures the net area of heated rooms (m2), the quota measures the design-shown pipe length (m), and the boundary between heating pipes and manifolds

Topic Positioning

Sorting out the measurement of floor radiant heating (underfloor coils): the bill basis by net heated-room area (m2), the quota / consumption basis by design-shown pipe length (m), and the quantity boundary between heating pipes and manifolds (heat-medium distribution and collection units). For tender quantities, rate conversion and trade-interface splitting.

Core Conclusions

1. Bill (measurement) basis - by net heated-room area (m2) GB/T 50856-2024 (quantity take-off standard for general building services), Annex K table K.4.1 "heating appliances" (code 031004) carries the item setting, item descriptions, units and measurement rules for heating-appliance bill items; "floor radiant heating" is measured in m2 on the design-shown net area of heated rooms. K.9.9 "notes on table K.4.1 heating appliances (code 031004)", original wording:

1 Types of steel radiator include closed-plate, panel, wall-panel, flat-tube and column radiators; radiator specifications mean height, length, number of sections and nominal diameter; 2 The work content of floor radiant heating shall include connection to the manifolds and co-ordination with floor casting; 3 The work content of floor radiant heating items shall include pressure testing and purging and cleaning - pressure testing covering the hydraulic, pneumatic, leak, water-fill and vacuum tests required by the design, purging and cleaning covering the water flushing and air blowing required by the design; 4 Types of heat-medium distribution unit mean: cased, uncased.

2. Quota (consumption) basis - by design-shown pipe length (m) Beijing DB11/T 2382-2024 Construction Works Consumption Quota Standard, section 6.10 "water supply, drainage, heating and gas works", heating appliances:

6.10.76 The quantities of floor radiant heating pipe laying shall be computed on the design-shown length; the conversion between heated-room net area and heating-pipe length may follow table 6.10.76.

Table 6.10.76 reference contents of floor radiant heating pipe per net heated-room area: pipe OD within 16 mm - floor radiant heating pipe content 6.300; within 20 mm - 5.775 (in m per m2 of net area).

The items themselves are also "per m": C10-7-41 (item name "pipe OD (mm, not exceeding) 16", owning table C.10.59), unit m, containing per m: all-in labour Grade II 0.0160 workday, floor radiant heating pipe 1.0200 m, floor-heating fixing clips 16 2.6250 No., plastic hose d25 0.0204 m, hacksaw blades 0.0024 No., nylon abrasive disc d100 3.0000%, pressure-test pump 0.0002 machine-shift, other plant 3.0000%. Work content: on-site handling, checking and cleaning of pipes, marking and setting out, pipe cutting, straightening, pipe layout, tying, fixing, hydraulic pressure testing and water flushing, co-ordination with floor casting etc.; the laying applies to pipes of aluminium-plastic composite, polybutylene, polypropylene, polyethylene and similar materials.

3. The railway system shares the basis - by pipe length, per 10 m TB/T 10831-2024 Railway Works Budget Quota Manual, Volume 10 building works, chapter 3 building services, section 2 heating works, "2. installation of heating accessories (8) low-temperature floor radiant heating" FY-2590 to FY-2592 (pipe OD not exceeding 16 / 20 / 25), unit 10 m. Work content: pipe cutting, straightening, pipe layout, tying, fixing, manifold installation, hydraulic pressure testing. Note the difference from Beijing: the railway items' work content already includes "manifold installation", while Beijing DB11/T 2382-2024 lists the heat-medium distribution unit as a separate item (table C.10.60-2.1) - check the system in force when applying, to avoid double pricing or omission.

4. The boundary with the distributor (collector) The boundary sits at the branch-pipe connections at the distributor / collector outlets: 1 Heating-pipe side (under "floor radiant heating pipe laying"): quantities run from the distributor outlet to the collector connection, including the pipe section rising from floor level to the connecting fitting; that section shall sit in a protective sleeve, and the connections of the heating pipe to the distributor and collector branch valves shall use dedicated compression-gland or plug-in fittings (DB62/T 3029-2018 clause 8.5.2 item 4). 2 Manifold side (under "heat-medium distribution unit installation"): DB11/T 2382-2024 Annex C table C.10.60-2.1 "installation of uncased heat-medium distribution unit", item C10-7-44 (item name "within 3 branches"), unit per set. Work content: on-site handling, checking, securing, installation of the unit, fabrication and fixing of supports, connection to the inlet and outlet pipes, water testing; the items band by the number of branch pipes at the distributor outlets, the work content including the installation of one distributor and one collector and their connection to the inlet and outlet pipes; valves, strainers and other accessories in the unit are computed separately (per set consuming the unit 1.0000 set, steel-plastic adaptors 6.0600, rolled sections 2.9998 kg, water-stop flange rings 50 4.0400, welding machine (general) 0.0577 machine-shift etc.).

Installation workmanship of distributors and collectors (DB62/T 3029-2018 clause 8.5.2): they may be installed before the heating pipes are laid, or after the pipes are laid and backfilled with fine-gravel concrete, together with valves and water meters; installation must be plumb and secure, and installation before backfill requires a hydraulic test. Horizontal installation preferably places the distributor above and the collector below, centre distance preferably 200 mm, the collector centre not less than 300 mm above the floor; vertical installation keeps the lower ends not less than 150 mm above the floor.

5. Rate conversion practice The bill reports m2; rate build-up derives pipe length as "heated-room net area x pipe content per unit area" and applies the per-m laying items; where the design spacing differs from the compiled spacing of the reference table, the content converts as 1 / spacing - the tabulated 6.300 / 5.775 cannot be applied directly.

6. Measurement of other heating appliances in the same section (DB11/T 2382-2024, 6.10.71 to 6.10.80) 6.10.71 heating-appliance installation sets items by appliance type and specification with the relevant codes; 6.10.72 flat-tube and wall-panel radiators follow the panel-radiator items with labour x 1.20; 6.10.73 the insulation course under floor heating may be compiled as 30 mm expanded polystyrene board, directly converting the insulation material where the design differs; 6.10.74 radiator installation quantities by design-shown count (the steel cradle content on insulated composite or non-load-bearing internal walls and the guard-cover content of finned-tube radiators per the design; finned-tube radiator installation includes the guard cover); 6.10.75 ranged-pipe radiator installation by the design-shown ranged-pipe length; 6.10.77 integrated prefabricated radiant heating (cooling) panels, capillary heat exchangers and prefabricated grooved insulation boards by design-shown area; 6.10.78 protective course (aluminium foil), insulation course and steel-mesh laying by design-shown area, edge insulation strips by design-shown length; 6.10.79 heat-medium distribution units and unit heaters by design-shown count; 6.10.80 air-collector fabrication and installation by design-shown count banded by shell diameter.

Applicability Boundaries

1 The bill basis serves tender BOQ compilation and measurement; the quota / consumption basis serves rate build-up and consumption analysis - never mix them in reporting; one heating item carries different units under the two bases (m2 and m), bridged by "pipe content per square metre". 2 The 6.300 / 5.775 of table 6.10.76 assume a specific compiled spacing; a different design spacing converts as 1 / spacing - no direct application. 3 The treatment of manifolds differs by system: railway TB/T 10831-2024 low-temperature floor heating items include manifold installation; Beijing DB11/T 2382-2024 lists the heat-medium distribution unit per "set" (C10-7-44, banded by distributor branch count, valves and strainers computed separately). Check the listing basis before borrowing quotas across systems. 4 Of the "floor radiant heating" row of GB/T 50856-2024 Annex K table K.4.1, the evidence gathered covers only the table head and code (031004), not the row's verbatim text; this card states it per the code's prevailing usage - verify against the current table K.4.1 before formal use. 5 The 2013 edition GB 50856-2013 Measurement Code for General Building Services Works has been replaced by GB/T 50856-2024 (quantity take-off standard), with the coding and table numbers carried over; note the edition when citing old numbers.

Further Reading

• GB/T 50856-2024 quantity take-off standard for general building services, Annex K water supply, drainage, heating and gas works: table K.4.1 heating appliances (code 031004) and K.9.9 "notes on table K.4.1".
• DB11/T 2382-2024 Construction Works Consumption Quota Standard, section 6.10, heating appliances (6.10.71 to 6.10.80, including the table 6.10.76 reference contents); Annex C general building services works, table C.10.59 (floor radiant heating pipe laying C10-7-41), table C.10.60-2.1 (installation of uncased heat-medium distribution unit C10-7-44).
• TB/T 10831-2024 Railway Works Budget Quota Manual, Volume 10 building works, chapter 3 building services, section 2 heating works, item 2 installation of heating accessories, (8) low-temperature floor radiant heating (FY-2590 to FY-2592).
• DB62/T 3029-2018 Technology Regulation for Building Water, Drainage and Heating Works, clause 8.5.2 "installation of distributors and collectors".