Fire on the Web

Fire Fighting Agents for Exposure Protection

Fire experiment comparing treated and untreated vinyl siding

Experience from previous wildland/urban interface fires indicates that they can be spread by burning brands. These fires start small in areas where the brands can collect, such as under eaves or in corners. If the structure can be protected from a small fire for a short period of time, the chances of the structure surviving the wildland/urban interface fire may increase dramatically.

This experiment demonstrates the use of durable agents (in this case a protein-based compressed air foam) for protecting building exteriors from ignition. Two exterior wall sections forming a corner were constructed with vinyl siding over sheathing on wood framing. One hour before ignition, Corner A was treated with a durable agent. Corner B received no treatment. Both corners were exposed to a 50 kW fire for 10 minutes. Within 3 minutes of ignition, Corner B (untreated) had flames extending into the eaves and roof area. After 10 minutes of fire exposure, Corner A had received only minor damage. The fire did not spread on Corner A.

This experiment demonstrates that durable agents applied to combustible exterior siding, reduces the likelihood of ignition and flame spread. Further research needs to be done to examine the effectiveness of durable agents under hot, dry and windy conditions.

Times are in seconds from ignition. Select a picture to view a larger version.


0 s 30 s 60 s 90 s
Corner A (treated)
Corner B (untreated)


120 s 150 s 180 s After the Fire
Corner A (treated)
Corner B (untreated)


View a movie of this fire by downloading one of the following quicktime or mpeg files.


case quicktime mpeg
treated vinyl siding (1.2 mb) treated.mpg (1.1 mb)
untreated vinyl siding (1.2 mb) untreated.mpg (810 kb)

Using a 28.8 kb modem, it takes about one minute to download each animation for every 120 kbytes in size.


For more information contact:

Daniel Madrzykowski