Hypermarkets and big-box retail stores are among the most demanding occupancies for sprinkler design: high racks, mixed commodity classes and back-of-house storage all overlap in the same project. This article covers an NFPA 13 EH1 design for the sales floor and the ESFR option for the back warehouse, from commodity classification to ESFR selection.
Determining the Commodity Class (NFPA 13 Section 20.4)
- Class I: Noncombustible products such as metal, glass and ceramics, placed directly on wood pallets, in single-layer corrugated cartons, or shrink- or paper-wrapped as a unit load (20.4.1)
- Class II: Noncombustible products in slatted wooden crates, solid wood boxes or multiple-layered corrugated cartons (20.4.2)
- Class III: Products made of wood, paper, natural fibers or Group C plastics; may contain up to 5% by weight of nonexpanded or 5% by volume of expanded Group A plastics (20.4.3)
- Class IV: Products made of Group B plastics, containing free-flowing Group A plastics, or containing roughly 5–15% by weight of Group A plastics (20.4.4)
- Group A plastics: Items with severe burning behavior such as expanded plastics (foam) and plastic hangers
Sales Floor Design (EH1)
- Design density: 0.30 gpm/ft² (12.2 mm/min) (Table 19.2.3.1.1)
- Design area: 2,500 ft² (230 m²)
- Storage height limit: 12 ft (3.7 m). Storage above this height is protected under the NFPA 13 storage chapters (Chapters 20–25); ESFR is one of the options.
- Water supply duration: 90 or 120 minutes for extra hazard, with a 500 gpm (1,900 L/min) hose allowance (Table 19.2.3.1.2)
- Sprinkler type: Standard response; NFPA 13 19.2.3.2.2.2 does not permit quick-response sprinklers in extra hazard occupancies. K8.0 (K115).
ESFR in Back-of-House Storage
- ESFR K14.0 (K200) to K25.2 (K360): The columns of NFPA 13 Table 23.3.1; maximum 40 ft (12.2 m) storage under a 45 ft (13.7 m) ceiling. Within the table limits no in-rack sprinklers are needed; which K-factor can be used at which height is read from the table.
- Ceilings above 13.7 m: NFPA 13 gives no ESFR or CMSA tables for this height; the only NFPA option is Chapter 24 Table 24.3.3 (dry, standard-response K25.2/K33.6 upright sprinklers, Class I–III) or a design with in-rack sprinklers. K28.0 (K400) and K33.6 (K480) ESFR are not in Table 23.3.1.
- Ceiling height: ESFR maximum 45 ft (13.7 m)
- Operating pressure: The lowest value for ESFR K14.0 (K200) is 50 psi (3.4 bar); the actual value is read from Table 23.3.1 for the ceiling and storage heights.
Mixed Commodities
- Group A plastics aisle: Treated as a separate hazard; EH2 or ESFR is required.
- Detergent/oil aisle: If aerosol products are present, NFPA 30B applies and a special design is needed.
- Spices/textiles: The standard Class III approach is sufficient.
- Barrier walls: Separating commodity groups keeps the higher design density local.
MEP Calc — 110+ Engineering Calculators
MEP Calc bundles 110+ engineering modules in one iOS app: 21 fire calculations (sprinkler, fire pump, FM-200 clean agent) plus heating, cooling, HVAC, plumbing, steam and natural gas. Download it on the App Store.
Download MEP Calc on the App Store
SprinkCalc — Fire Sprinkler Design Across Three Standards
SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report. One of the few tools that unifies all three major fire protection standards.
Download SprinkCalc on the App StoreNFPA 13 Chapter 20-25, FM Global DS 8-9, FM Global DS 8-1. NFPA 13 Sprinkler standard.