NFPA 285 Fire Testing

Have you ever wondered about walls being tested for fire safety? If you don’t know what an NFPA 285 is or haven’t heard of it before, you’re probably in the same boat as 95% of the rest of the world (a completely made up estimation). However, this particular standard may be of interest, as it involves testing the ability of fire to spread on certain wall components. The National Fire Protection Agency (NFPA) published these standard fire tests to evaluate the ability of an exterior wall to resist certain flame propagation. In other words, to see how quickly and excessively fire travels up walls.

Image: Kenny Eliason on Unsplash 

NFPA 285 Fire Testing

The walls are evaluated by their ability to resist:

  • Flame propagation over the exterior wall surface
  • Vertical flame propagation within the combustible core or components
  • Vertical flame propagation over the interior surface from one floor to the next
  • Lateral flame propagation to adjacent compartments.

What does this look like? Let’s get to the interesting part – actually fire testing the walls.

Image: Ricardo Gomez Angel on Unsplash 

NFPA 285
NFPA 285

The NFPA 285 test takes place using a prop that is 18 feet tall, 13 feet and 4 inches wide, and has a 78-inch-wide window opening. Two gas burners are the fire sources, with one located inside the first floor, and one as a window burner on the exterior side. The wall to be tested is assembled just like it would be assembled in the field. Normally, these tests are required for buildings with certain types of occupancies (I, II, III, or IV), especially if the buildings have multiple stories. The fire is started on the first floor, and the plume that comes out of the window on the exterior of the wall is what is being measured. The purpose of the test is to see if the fire will travel up the wall too high or to the sides of the wall too widely, spreading to other floors of the building. The goal is to prevent combustibles on the second floor from igniting. One of the pass/fail criteria of the NFPA 285 is if the fire reaches over 10ft high within a certain timeframe.

The International Association of Fire Fighters (IAFF) performs NFPA 285 testing on combustible facades. Watch the actual fire testing here.

To pass an NFPA 285 test standard, there are six requirements that must be met.

  1. Flames not visually observed on the exterior wall 10ft or higher above or 5ft or greater from the center of the window opening.
  2. Exterior thermocouples at 10ft vertically and 5ft laterally from the window opening do not exceed 1,000 degrees F.
  3. Temperature rise does not exceed 1,000 degrees F within any wall cavity air space.
  4. Temperature rise does not exceed 750 degrees F within any combustible wall components more than ¼ inch thick.
  5. Temperature rise does not exceed 500 degrees F within the second story test room, measured 1 inch from the interior wall assembly surface.
  6. Flames are not visually observed within the second story test room.

Image: Ricardo Gomez Angel on Unsplash 

Tech Tips with Bob NFPA 285
Tech Tips with Bob NFPA 285

These types of tests are extremely crucial, as there have been some incidences where the wrong materials were used, and buildings and their occupants suffered from fires that spread rapidly. When buildings are being designed, it’s important to talk with an experienced building envelope expert (such as Bob Sanderson at DC) to coordinate NFPA 285 building envelope compliant assemblies with the project manager. The safety of building occupants is the most important piece of designing a space.

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