What Is Flue Space? Why It Matters.

Flue space refers to the vertical and horizontal gaps between pallet racks that allow heat and smoke to rise evenly during a fire. These open spaces help sprinkler systems activate properly and prevent flames from spreading between pallets or racks.

Without adequate flue space, a warehouse’s fire suppression system can be severely compromised — heat can build up, sprinklers may not reach the source of the fire, and the blaze can spread rapidly through stored materials.

There are two main types of flue space:

• Transverse flue space: the front-to-back gap between pallets on the same rack.

• Longitudinal flue space: the space between back-to-back racks.

Building and fire codes such as NFPA 13 and local Authority Having Jurisdiction (AHJ) standards define how much spacing is required, typically between 6 and 12 inches depending on rack design, pallet load, and sprinkler configuration. Maintaining consistent spacing not only keeps facilities in compliance with fire code but also satisfies insurance requirements set by risk control partners like FM Global, Travelers, and Liberty Mutual.

At WareCraft Solutions, we help warehouses meet these safety and compliance standards without sacrificing valuable storage space. Our customizable flue space dividers ensure racks maintain uniform spacing — often reducing gaps to a compliant 8 inches — increasing pallet density while staying fully within code.

Properly maintained flue space protects your people, your property, and your insurance rating. It’s one of the simplest, most cost-effective steps a facility can take to stay compliant and efficient.