Oregon Building Code Updates

November 2010

Changes from the 2006 IBC model to the 2009 IBC model and the 2009 OSSC:

They rewrote much of Chapter 5; more specifically, they erased large portions of Chapter 5. If you are trying to figure out what happened to food areas adjacent to Assembly and Educational Occupancies, they left. All of the calculations regarding what was accessory-to and what wasn’t, just sort of dissolved. Spaces accessory to major Uses are now Accessory Uses; and Incidental Uses became Incidental Accessory Occupancies… the latter remaining largely unchanged. Parking Garages have been removed from the Incidental Accessory Occupancy category, and have returned to being a separate Occupancy. Storage rooms have also been removed from the Incidental Accessory Occupancy category… [If you don’t like what the Code says, just wait 3-6 years; it will change. One of the reasons I get really impatient with Plans Examiners who are highly detail oriented…but that’s another rant]

The Code has once again caught up to Portland and expanded the Occupancies permitted in the bottom level[s] of ‘pedestal buildings’. As long as there is a Three-hour horizontal separation, and the bottom level[s] are of Type I construction and sprinklered, almost anything can be located in the bottom level[s].

    Sometimes I think there should be a requirement that somewhere there should be an explanation as to why sections of the Code are changed…

    506.5.2 Mixed Occupancy buildings with more than one story above the grade plane. It is now required that in a building with mixed Occupancies, each story must individually comply with the Allowable Area limitations; and the entire building must also comply. If the building has more than 3 stories above the grade plane, “the total building area shall be such that the aggregate  sum of the ratios of the actual area of each story divided by the allowable area of such stories…shall not exceed 3.”

    The ICC then gives an example of a building that is basically maxed-out in area at 4 stories. Being one who is more concerned with how big buildings can be, rather than how small, I put some additional numbers to their example:

    Their example shows a 4-story motel with 46,000sf per floor. The sum of the ratios for the building, at the Occupancy areas shown, is 2.83<3.0. The single-Occupancy floors are 64% of the Allowable Area per floor. An additional story would not be possible. This isn’t a big building.