Warehouse and Industrial Fire Protection Design

What You Need to Know

Warehouses and factories carry some of the highest fire risks in the built environment. Large open floor plates, high ceilings, concentrated storage, and limited compartmentation mean fires can grow rapidly before detection. NCC 2025 sets specific fire protection requirements for Class 7 (storage) and Class 8 (factory/laboratory) buildings that go well beyond what is required for a standard commercial fitout.

A fire protection package for a typical warehouse includes sprinklers, fire hydrants, hose reels, smoke detection, smoke exhaust, fire compartmentation, and fire brigade access. For a standard warehouse of 2,000 to 5,000 m2, expect to spend $80 to $150 per square metre on fire protection. High-hazard facilities with in-rack sprinklers or dangerous goods storage can reach $200 to $350 per square metre.

The critical variable is sprinkler classification. AS 2118.1 classifies warehouses from Ordinary Hazard (OH) through to High Hazard (HH4) based on what is stored and how high it is stacked. This classification drives everything: sprinkler head spacing, pipe sizing, water supply capacity, pump requirements, and tank volume. Getting the classification wrong means the entire system is undersized or oversized.

Insurance is the other major driver. Even where NCC does not mandate sprinklers, insurers frequently require them as a condition of cover. A warehouse without sprinklers may face premiums 3 to 5 times higher than one with a compliant system, or may be uninsurable altogether for certain stock types.

• Sprinklers are required for Class 7 and Class 8 buildings exceeding 5,000 m2 floor area or 18,000 m3 fire compartment volume. Buildings with effective heights over 25 m also require sprinklers regardless of area. Smaller buildings may still need sprinklers based on fire load or dangerous goods storage. (NCC 2025 Spec 20, Table 7)
• Sprinkler systems must comply with AS 2118.1 for design, installation, and commissioning. The standard classifies occupancies from Extra Light Hazard through to High Hazard 4. Warehouses typically fall into Ordinary Hazard Group 3 (OH3) or High Hazard categories depending on stored commodities and storage height. (AS 2118.1:2017)
• Fire hydrant systems are required for buildings exceeding 500 m2 in floor area. Hydrants must comply with AS 2419.1 and be located so that all parts of each storey can be reached by a 10 m hose stream from the nearest hydrant. External hydrants provide fire brigade access points. (NCC 2025 Spec 17, AS 2419.1:2005)
• Hose reels are required in all buildings with a total floor area exceeding 500 m2. Every point on each floor must be within 36 m of a hose reel (measured along a path of travel). Hose reels are first-response equipment for occupants, not a substitute for hydrants. (NCC 2025 Spec 16, AS 2441:2005)
• Smoke detection and alarm systems must comply with AS 1670.1. Large open warehouse spaces present challenges for point-type smoke detectors due to ceiling height and air movement. Beam detectors or aspirating (VESDA) systems are commonly used for spaces with ceiling heights above 6 m. (AS 1670.1:2018)
• Smoke hazard management is required under NCC 2025 Part E2. Warehouses may use natural ventilation (openable vents) or mechanical smoke exhaust to maintain tenable conditions during evacuation. The system must be designed to keep smoke above 2.1 m from finished floor level for the required evacuation time. (NCC 2025 Part E2, AS 1668.1)
• Fire compartmentation limits maximum compartment size. Where sprinklers are not provided, maximum compartment size for Class 7 and 8 buildings is 2,000 m2. With sprinklers, this increases to 8,000 m2. Fire walls must achieve the required Fire Resistance Level (FRL) and extend to the underside of the roof. (NCC 2025 Part C2)
• Dangerous goods storage must comply with AS 1940 in addition to NCC requirements. AS 1940 sets requirements for storage quantities, separation distances, bunding, ventilation, and fire protection specific to the class of dangerous goods stored. This may require additional sprinkler protection, foam systems, or gas suppression. (AS 1940:2017)
• Fire brigade access and booster assemblies are required under NCC 2025 Part E1. The booster assembly allows the fire brigade to supplement the building's water supply. Access roads must support fire appliance loading and provide adequate turning circles. Hard-stand areas must be within 18 m of the booster. (NCC 2025 Part E1, AS 2419.1)

The first step in warehouse fire protection design is determining the sprinkler hazard classification. This depends on what will be stored, how it is packaged, how high it is stacked, and the aisle configuration. General merchandise on pallets stacked to 3.5 m or less typically qualifies as Ordinary Hazard Group 3 (OH3). Plastics, aerosols, flammable liquids, rubber tyres, or goods stacked above 3.5 m push the classification into High Hazard territory.

For OH3 warehouse sprinkler design, AS 2118.1 requires a design density of 5.0 to 8.0 mm/min over an area of operation of 216 to 360 m2. For High Hazard 3 (HH3), the density increases to 12.5 to 17.5 mm/min over 260 m2. These numbers directly determine the pipe sizing, pump capacity, and water storage volume.

Rack storage introduces additional complexity. When goods are stored on racking above 3.5 m, ceiling-level sprinklers alone may not control a fire that starts deep within the rack structure. AS 2118.1 requires in-rack sprinklers at intermediate levels for storage above certain heights. The alternative is Early Suppression Fast Response (ESFR) sprinklers at ceiling level, which are specifically designed for high-challenge warehouse fires. ESFR heads discharge at much higher flow rates (typically 300 to 450 L/min per head) and are designed to suppress fires rather than just control them.

The choice between in-rack sprinklers and ESFR has significant implications. In-rack systems are effective but restrict rack layout changes. Moving racks means relocating sprinkler pipework, which is expensive. ESFR systems sit at ceiling level and do not restrict rack configuration, but they require minimum ceiling heights (typically 9 to 13.7 m depending on storage height) and much larger water supplies. A warehouse with ESFR protection may need a fire pump delivering 6,000 to 10,000 L/min compared to 2,000 to 4,000 L/min for a conventional OH3 system.

Smoke detection in warehouses requires careful selection. Standard point-type smoke detectors (the type used in offices) are ineffective in spaces with ceiling heights above 6 m because smoke cools and stratifies before reaching the ceiling. Beam detectors project an infrared beam across the space and detect smoke passing through the beam path. Aspirating systems (VESDA) use a network of sampling pipes to actively draw air to a central detector, offering very early warning in large volumes. For warehouses with ceiling heights above 10 m, aspirating detection is often the most reliable option.

Smoke exhaust design for warehouses follows either natural or mechanical approaches. Natural smoke venting uses roof vents (typically 2% of the floor area) that open automatically on fire detection. Mechanical smoke exhaust uses fans to extract smoke and maintain a clear layer below 2.1 m. The choice depends on building height, roof construction, and whether the warehouse has a mezzanine. Warehouses with mezzanines usually need mechanical systems because natural venting alone cannot manage smoke travel to the mezzanine level. Smoke exhaust design must coordinate with the smoke exhaust fan sizing requirements and the sprinkler system, since sprinkler activation cools smoke and can cause it to descend.

Fire compartmentation in warehouses is often challenging because the operational requirement is for large, open floor plates. NCC allows compartments up to 8,000 m2 with sprinklers, which suits most warehouse layouts. Where larger compartments are needed, a fire-engineered alternative solution (Performance Solution) is required. Fire separation walls between tenancies in multi-tenancy industrial estates must extend from floor to the underside of the roof and achieve the required FRL. Services penetrating fire walls need compliant fire collars, wraps, or sealants.

Dangerous goods storage under AS 1940 adds a separate layer of requirements. Buildings storing more than minor quantities of Class 3 (flammable liquids), Class 4 (flammable solids), or Class 5 (oxidising agents) dangerous goods need specific fire protection measures including bunding, separation distances from boundaries, additional sprinkler protection, and potentially foam-water deluge systems. The fire protection design cannot be finalised until the dangerous goods manifest is confirmed.

Fire brigade access is a common oversight. The booster assembly must be located on the street frontage, accessible within 18 m of a hard-stand area suitable for a fire appliance. For large warehouse complexes, internal fire brigade access roads may be required, with minimum 6 m widths, 12.5 m turning radii, and load ratings for a 28-tonne fire appliance. The access design often affects the civil and landscape design and should be coordinated early.