Fire Compartment Area Lookup
Category, fire rating and sprinklers in; compartment limit out.
Quick answer
With the default inputs: Building category Low and multi-storey civil · Fire resistance rating Grade I or II · Automatic sprinkler system Full protection etc.Max fire compartment area 5000 m²
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Result
Max fire compartment area
5000m²
| Tabulated value | 2500m² |
| Sprinklers (note 1) | Full protection, +100% |
| Result | 5000m² |
| Basis | Low or multi-storey, grade I-II |
Based on GB 50016-2014 (2018) Table 5.3.1 and notes 1-3. A full sprinkler system doubles the tabulated area; partial protection doubles only the protected portion. The retail and exhibition hall values already assume sprinklers, alarm and non-combustible finishes, so they must not be doubled again. Atria, escalator openings, fire shutters and industrial buildings have separate rules; the full code and the fire review comments govern.
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Formula
| Lookup | Table 5.3.1 by category × fire rating |
| High-rise | 1500 m² for grade I-II (grade III+ not allowed) |
| Low/multi | 2500 grade I-II; 1200 grade III; 600 grade IV |
| Basement | 500 m²; plant rooms 1000 m² |
| Sprinklers | add 100% to the tabulated value (×2) |
| Retail halls | 4000 high-rise / 10000 single or ground floor / 2000 basement, already sprinkled |
Multi-storey civil, grade II, fully sprinklered, general use: 2500 m² tabulated, doubled for sprinklers, so 5000 m² per compartment.
How to work it out
- Establish the building category: high-rise civil, low or multi-storey civil, or basement or semi-basement. Permitted areas differ by more than a factor of two between categories.
- Establish the fire resistance class (1 to 4). This follows from the combustibility and fire resistance rating of the elements, and is determined by height and occupancy — it is not a free choice.
- Read the base value: 1500 m² for class 1 and 2 high-rise (classes 3 and 4 are not permitted for high-rise); 2500 m² for class 1 and 2 low or multi-storey, 1200 for class 3, 600 for class 4; 500 m² for basements, or 1000 for plant rooms.
- Where automatic extinguishing is installed, increase the table value by 100% — that is, double it. This is the usual uplift, but only for areas that are actually protected.
- Retail halls and exhibition halls have their own values: 4000 m² in high-rise, 10,000 m² for single-storey or ground-floor locations, 2000 m² underground. These already assume sprinklers, detection and non-combustible finishes, so doubling again is wrong.
- Check that the compartment boundaries align with structural joints and fire walls. A boundary must be a fire wall, fire shutter or floor slab — a dashed line on a drawing is not a boundary.
Where it goes wrong
- Doubling everything once sprinklers are present. Only areas protected by an automatic extinguishing system qualify, and partial coverage does not justify doubling the whole compartment.
- Looking up retail halls under general occupancy and then doubling. The dedicated values already include sprinklers; doubling gives 8000 m² and a gross non-compliance.
- Applying low-rise values to basements. At 500 m² against 2500 m² above ground, the error under-provides several compartments and the fire review rejects the design.
- Considering area but not the boundary. Compartments need physical separation by fire walls, shutters and doors; atria, escalators and service shafts all need individual treatment.
- Forgetting the separate provision for plant rooms. Basement plant rooms get 1000 m² rather than 500, but require independent separation and escape.
Material and cost
Smaller compartments mean more fire walls, doors and shutters. A 500 m² basement compartment needs an extra separation set compared with 1000 m², adding 50,000-150,000 CNY. But failing fire acceptance costs far more — demolishing and rebuilding fire walls, redesigning the fire strategy and losing months of programme.
On site
- Compartment area is measured as construction area per GB/T 50353, not usable area.
- Where a fire wall is genuinely impossible, a fire shutter may substitute, but shutters cannot be strung together indefinitely — their width is limited, typically to a third of the relevant external wall width.
- Atria must be compartmented separately with separation from surrounding space — the central issue in retail fire design.
- Seal escalators, open stairs and service shafts where they pass through slabs. Otherwise floors merge into one compartment and the area is grossly exceeded.
Basis
- GB 50016-2014 (2018 edition) Code for fire protection design of buildings, maximum permitted area of fire compartments
- GB 50016-2014 (2018 edition) Code for fire protection design of buildings, building construction
- GB 50067-2014 Code for fire protection design of garages, repair garages and parking lots
FAQ
Does a sprinkler system really double the compartment area?
Yes, but only with full protection - the whole compartment must be covered. Partial protection allows doubling only of the protected portion. The system must also be properly designed, accepted and maintained; shown on drawings but not commissioned does not count.
Why can a single-storey retail hall reach 10000 m²?
Because egress is easiest: people exit directly to grade, no stairs, short smoke travel. Even then it requires sprinklers, detection and non-combustible or hard-to-burn finishes together - all three. High-rise is capped at 4000 m² and basement at 2000 m², following the rising difficulty of escape.
Do fire shutters count the same as fire walls?
A fire wall is a true separation; shutters are a substitute with tight limits and cannot replace fire walls for compartmentation in general (atria and escalator openings are the recognised exceptions, subject to width and rating rules). A failed shutter means no separation, which is why width, integrity rating and interlock control are reviewed so closely.
Cite this page
Use this format in reports, method statements or coursework. The link is permanent.
Building Calculator. Fire Compartment Area Lookup. 2026-10-25. https://jianzhujisuan.com/en/fire-compartment
Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.