Interesting Facts About This Fire

  • 3-alarm fire
  • Burned for several hours
  • Appears to have started in a meat market right below the beam
  • The cause of the fire is still under investigation

Download the APA Technical Document on Calculating Fire Resistance for Glulams and Columns

Glulam Fire Resistance

Case Study

The last thing you want to hear as a business owner is that your livelihood has been taken away due to a fire. Sadly, this was an all too familiar reality to five business owners December 31st, 2012 just before the clock struck midnight. Shortly after 11pm firefighters responded to a fire in the Academy Square strip mall, located in Salem, Oregon. The fire spread fast across the five businesses, turning everything in its path into ash; everything but the glulam beams the building was designed around.

When you think of fire, and what will hold up the best, wood is the last thing in most people's minds. However, when the smoke had finally cleared and as clean-up crews moved in to sort through the damage, they were shocked to see that the last thing standing were the glulam beams (see picture of beam standing). They were in fact, so sound, that crews had to use their backhoes and bulldozers to physically break the beams in half to get them down (see picture of beam broken in half with char on outside).

The fact is, glulam beams have been tested against other leading materials in fire resistance and glulam consistently out performs in every category. The average building-fire temperature ranges from 1290° to 1650° Fahrenheit. Wood will not ignite until it reaches almost 500° Fahrenheit. Once heavy timber does ignite, it develops char at a rate of 1/40th inch per minute under an ASTM E-119 fire exposure (download AITC document). The slowness of burn is due to the inherent property of wood to naturally insulate in a fire.

Unprotected metals, on the other hand, lose their strength quickly in a fire and often collapse suddenly due to their rapid loss of strength. Studies have shown that within 10 minutes of a fire starting, steel loses its structural properties by over 50%, while glulam still holds over 80% of its strength.*

The reality is that no building is fire-proof since most fires start with the structure's contents. The goal of fire-resistive construction is to allow occupants adequate time to evacuate the structure safely. Thankfully, no one was injured in this fire and there are plans to rebuild.

Note: Glulam beams specified with a one-hour fire rating do require additional lay-up modifications. During this process an inner lamination is replaced by an additional tension lamination to the bottom of the beam.

*As published in the American Institute of Timber Construction Super Fire Resistance, page 4. Results from test sponsored by National Forest Products Association at the Southwest Research Institute.

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