NFPA Fire Terms That Industrial Tenants and Landlords Need to Know
Understanding NFPA 13: Key Fire Protection Terms for Industrial Properties
Fire protection codes are full of technical jargon that most people in industrial real estate don’t think about—until they have to. Whether you're a warehouse tenant, landlord, or broker, understanding NFPA 13 terminology can help you avoid costly fire code violations, insurance issues, or unexpected sprinkler system upgrades.
Below is a quick reference guide to some common NFPA fire protection terms used in industrial buildings.
Encapsulated Storage
Definition: Products wrapped in plastic that covers the top and at least 75% of the sides.
Why It Matters: Plastic traps heat and prevents sprinkler water from penetrating the product, making fires harder to suppress.
Example: A pallet of boxed paper is a lower fire risk than the same pallet shrink-wrapped in plastic, which may require a higher sprinkler density or in-rack sprinklers.
Obstruction to Discharge
Definition: Any object that blocks sprinkler water from reaching a fire.
Why It Matters: Sprinklers are designed to spray water in a specific pattern—if racking, equipment, or solid shelving blocks that spray, fire protection is compromised.
Example: A warehouse with solid shelves in a rack system might require in-rack sprinklers because the shelves prevent water from reaching lower levels.
Commodity Classification (Classes I–IV & Group A Plastics)
Definition: NFPA 13 groups stored materials by how fast they burn and how much fire protection they require.
Why It Matters: The higher the classification, the more fire protection is needed.
Commodity Class Breakdown:
Class I – Noncombustible materials like metal parts (lowest fire risk).
Class II – Noncombustible products with limited combustible packaging.
Class III – Combustible products such as wood, paper, and natural fiber clothing.
Class IV – Class III materials with additional plastic or combustible content, such as cardboard boxes with foam inserts.
Group A Plastics – Highly combustible plastics, including plastic crates, shrink-wrapped goods, and synthetic clothing like polyester (highest fire risk).
Many everyday products that appear harmless such as polyester fabrics, foam products, rubber items, or shrink-wrapped goods—may fall into higher commodity classifications depending on their plastic content. (See examples of materials commonly treated as plastics under NFPA standards.)
Example: A warehouse storing cotton clothing (Class III) requires a different fire suppression system than one storing polyester clothing (Group A Plastics).
High-Piled Storage
Definition: Storage exceeding 12 feet for certain commodities or 15 feet in general cases.
Why It Matters: Once storage reaches high-pile classification, NFPA requires stricter fire suppression, which may include:
Higher sprinkler density
In-rack sprinklers
Additional water supply capacity
High-piled storage requirements are addressed in detail under NFPA 13 Chapter 20, which outlines how storage height, commodity class, and rack configuration directly affect sprinkler design and water demand.
Example: A warehouse storing small boxes on floor pallets has fewer fire requirements than one using 20-foot racking for high-pile storage.
Solid Pile vs. Palletized Storage
Definition:
Solid pile – Goods stacked directly on top of each other.
Palletized storage – Goods stored on pallets with airflow between them.
Why It Matters: Solid pile storage burns hotter and faster than palletized storage, affecting sprinkler system requirements.
Example: A warehouse stacking clothing in solid piles may need a different fire suppression system than one using palletized racking with flue spaces.
Flue Space
Definition: Vertical gaps between stored goods that allow sprinkler water to flow down.
Why It Matters: Without proper flue space, fire suppression can’t reach lower levels, increasing fire risk.
Example: Fire inspectors may require a 6-inch transverse flue space between pallets in racks to allow proper water flow.
ESFR (Early Suppression, Fast Response) Sprinklers
Definition: High-output sprinklers designed to suppress fires quickly rather than just containing them.
Why It Matters: ESFR systems eliminate the need for in-rack sprinklers but may require higher water pressure than a standard system. Different buildings may use different fire sprinkler systems and sprinkler head types depending on storage hazards, building height, and water supply.
Example: A FedEx-style distribution center likely has ESFR, but a converted manufacturing building may not.
Limited-Combustible vs. Non-Combustible Materials
Definition:
Non-combustible – Does not burn (e.g., metal, glass).
Limited-combustible – Can burn, but not easily (e.g., fire-treated wood).
Why It Matters: Some materials appear fire-resistant but still contribute to fire spread.
Example: Certain fire-treated insulation materials may be limited-combustible rather than fully non-combustible.
Water Demand & Fire Flow
Definition: The amount of water needed to sustain sprinkler discharge for a required period (usually 20–90 minutes).
Why It Matters: If a warehouse lacks sufficient water pressure, it may need:
Fire pumps
On-site water storage tanks
Example: Older industrial buildings may not have enough water supply capacity to support modern sprinkler requirements.
Aisle Width & Fire Code Compliance
Definition: NFPA sets minimum aisle widths between racked goods to allow for:
Proper fire suppression
Emergency access
Why It Matters: If aisles are too narrow, fire code may require:
Layout adjustments
Additional sprinklers
Example: A warehouse reconfiguring racks may unknowingly reduce aisle width below fire code minimums, affecting compliance.
Why This Matters for Industrial Leasing
Fire codes play a key role in warehouse operations, affecting tenant approvals, insurance requirements, and long-term compliance.
Understanding fire protection requirements upfront helps tenants select the right space and avoid unexpected modifications.
Well-maintained sprinkler systems and proper fire suppression measures add value to a warehouse, ensuring it meets various storage needs.
Different commodities and storage heights require different levels of fire protection, making it important to match a space with the right tenant.
For businesses considering a warehouse, confirming that the fire suppression system aligns with your planned storage type ensures a smooth move-in process