U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Firewood Piles

A photo of a tall and narrow stack of firewood burning in front of a shed under a wind speed of 6 meters per second or 13 miles per hour. The logs are 41 centimeters or 16 inches long and are stacked 1.22 meters or four feet high by 61 centimeters or two feet long, at a distance of 3.66 meters or twelve feet from the shed. The logs are oriented parallel to the shed. Flames extend out from the sides of the lower half of the stack.
A photo of a tall and narrow stack of firewood burning in front of a shed under a wind speed of 6 m/s (13 mi/h). The logs are 41 cm (16 in) long and are stacked 1.22 m (4 ft) high by 0.61 m (2 ft) long on a rack at a distance of 3.66 m (12 ft) from the shed.
Credit: Rik Johnsson/NIST

A series of field experiments was conducted to examine the effects of burning firewood piles on fire spread toward a structure under conditions that may be encountered during a WUI fire. The fire behavior of a variety of firewood species in multiple configurations was studied under various wind conditions. The 62 experiments conducted included long range firebrand travel and fire spread mitigation experiments. Wood species included kiln-dried maple, oak [dried and not dried (“green”)] and eastern white pine. Configuration variations included woodpile height, orientation, and elevation on a rack. A wind machine provided a mean wind speed between a nominal 6 m/s and 14 m/s (13 mi/h to 31 mi/h). The woodpiles were ignited by a propane burner on the ground at the end farthest from a small structure located between 0.91 m and 7.32 m (3 ft to 24 ft) downwind of the woodpile. A target mulch bed at the base of the structure evaluated the ability of firebrands produced by the burning woodpile to ignite spot fires that could threaten the structure.

A photo of a low and wide stack of wood burning in front of a shed under a wind speed of 10 meters per second or 22 miles per hour. The logs are 16 inches long and are stacked 2 feet high by 4 feet long, at a distance of 6 feet from the shed. The logs are arranged perpendicular to the shed, so that the ends face the shed. Flames extend directly toward the shed.
A photo of a low and wide stack of dry oak firewood burning in front of a shed under a wind speed of 10 m/s (22 mi/h). The logs are 41 cm (16 in) long and are stacked 0.61 m (2 ft) high by 1.22 m (4 ft) long, at a distance of 1.83 m (6 ft) from the shed. 
Credit: Rik Johnsson/NIST

The experiments in this study demonstrated that firewood piles can be rapid sources of spot fire ignitions and can easily spread fire to nearby structures. Rapid fire growth on and substantial flames from the woodpiles were found for all wood species and configurations. Fire behavior was classified as high hazard for igniting spot fires under all wind conditions.

In all cases, spot fire generation was affected by the wind field; the structure created both upward flow (enhanced by buoyancy) and a vortex that deposited firebrands next to the structure. During all experiments, the burning woodpile produced firebrands that ignited spot fires in the target mulch bed. In long range experiments, firebrands from a woodpile caused ignitions over 26 m (85 ft) downwind.

 

PUBLICATIONS

Johnsson, E., et al. (2023) Wind-Driven Fire Spread to a Structure from Firewood Piles. NIST Technical Note 2251.
https://doi.org/10.6028/NIST.TN.2251

Fire and Wildland urban interface fire

Contacts

Created September 29, 2026, Updated September 30, 2026
Was this page helpful?