Depending on the size of the building wood can have a better fire survivability rating than steel as wood beams take a long long time to burn through to a point of failure. While a correspondingly strong steel beam would lose its ability to remain rigid.

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>A fire test conducted in 1961 at the Southwest Research Institute compared the fire endurance of a 7x21-inch glulam timber with a W16x40 steel beam. Both beams spanned approximately 43.5 feet and were loaded to full design load (approximately 12,450 lb.). After about 30 minutes, the steel beam deflected more than 35 inches and collapsed into the test furnace, ending the test. The wood beam deflected 2 1/4 inches with more than 75% of the original wood section undamaged. Calculation procedures provided in a new publication available from the American Wood Council, entitled Technical Report 10: Calculating the Fire Resistance of Exposed Wood Members, estimates that the failure time of the 7x21-inch wood beam would have exceeded 65 minutes if the test had not ended at 30 minutes.

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Of course wooden beams large enough to build a modern sky scraper would be so large they would eliminate all interior volume making them a non practical choice. But for low rise apartments it can be a good choice.