OBC 2009 CHAPTER FIVE GENERAL BUILDING HEIGHTS AND AREAS

OVERVIEW  REGULATES THE MINIMUM TYPE OF CONSTRUCTION  AREA MODIFICATIONS  HEIGHT MODIFICATIONS  MEZZANINES REQUIREMENTS  UNLIMITED AREAA STRUCTURES.  PARKING GARAGES RELATED ISSUES.

OBJECTIVES  USE TABLE 503  ADDITIONAL PROTECTION FEATURES TO MODIFY HEIGHTS AND AREAS.

ALLOWABLE AREA  ESSENTIALS TO DETERMINE THE ALLOWABLE AREAS: –TYPE AND AMOUNT OF COMBUSTIBLES DUE TO USE OF BUILDING –AMOUNT OF COMBUSTIBLES CONTAINED IN THE CONSTRUCTION OF A BUILDING –SPRINKLER, OPEN YARD, FIRE WALL

AREA LIMITATIONS  DETERMINE THE TABULAR AREA  MODIFY THE TABULAR AREA  MAXIMUM BUILDING AREA IS INTENDED TO LIMIT THE SIZE OF THE FIRE AND TO CONTROL THE SPREAD OF FIRE, LIFE SAFEY, ACCESS TO FIRE DEPARTMENT PERSONNEL.  MEZZANINE DOES NOT CONTRIBUTE TO BUILDING AREA  MAXIMUM ALLOWABLE AREA IS LIMITED TO ALLOWABLE AREA PER FLOOR MULTIPLIED BY THREE.

HOW DO WE DETERMINE THE CONSTRUCTION TYPE  1. IDENTIFY THE USE  2. IDENTIFY AREA AND HEIGHT  3. DETERMINE THE CONSTRUCTION TYPE  NOTE: IF THE USE AND CONSTRUCTION TYPE ARE DEFINED BY THE DESIGN PROFESSIONAL THEN THE AREA AND HEIGHT LIMITATIONS WILL BE ESTABLISHED FROM TABLE 503

TABLE 503  ALLOWABLE HEIGHT AND AREA  USE GROUP  CONSTRUCTION TYPE  NUMBER OF FLOORS  AREAS PER FLOOR  HEIGHT: # OF STORIES AND FEET ABOVE GRADE PLANE

EXAMPLES  M USE, IIB  AREA:  HEGHT:  # OF STORIES:

HEIGHTS MODIFICATIONS  504 –SPRINKLER SYSTEM NFPA 13 A MAXIMUM OF ONE STORY A MAXIMUM ADDITIONAL HEIGHT OF 20 FEET. R USES IS LIMITED TO FOUR STORIES AND 60 FEET IF NFPA 13R IS USED

EXAMPLE  B USE, IIB, NFPA 13 –4 STORY –75 FEET –AREA INCREASE

AREA INCREASE  506 –A a = A t + { A t I f /100} + { A t I s /100} –Frontage and sprinkler increase –I f = 100[F/P –0.25]W/30 W Minimum 20 feet Weighted average If W > 30 USE 30 –W=60 IF ALL REQUIREMENTS OF 507 ARE MET EXCEPT 60 FOOT

AUTOMATIC SPRINKLER SYSTEM  200 % FOR MULTISTORY STRUCTURES  300 % FOR SINGLE STORY BUILDINGS.  SEE THREE EXCEPTIONS OF SECTION 506.3

MIXED USES 508 OBC  INCIDENTAL USE AREAS –SEPARATED OR PROTECTED PER TABLE  MIXED OCCUPANCIES –ACCESSORY USE AREAS –NONSEPARATED –SEPARATED USES –TABLE  2007 CHANGES  502.1, 202 DEFINITIONS OF BASEMENT AND STORY ABOVE GRADE PLANE.  TABLE 503 MODIFIED FOR H-5 USE.  UNLIMITED HEIGHT AND AREA FOR SPECIAL INDUSTRIAL OCCUPANCY F- 1 AND F-2 ONLY  MODIFICATION OF SECTION HEIGHT INCREASE TO THE ENTIRE FIRE AREA

2007 CHANGES  AN ADDITION TO SECTION FLOOR AREA OF MEZZANINE LIMITED TO 50% OF ROOM IN WHICH IT IS LOCATED TYPE I OR II, FYLLY SPRINKLERED, AND EMERGENCY VOICE/ALARM COMMUNICATION SYSTEM

2007 CHANGES  AN ADDITION TO SECTION NEW EXCEPTION ALLOWES FOR TOTAL ENCLOSURE OF A MEZZANINE IF THERE ARE AT LEAST TWO MEANS OF EGRESS.  CLARIFICATIONS FOR ALLOWABLE AREA CALCULATIONS, 506.1, 506.2, 506.3

2007 CHANGES  CLARIFICATIONS TO SECTION FOR I f CALCULATIONS  MODIFICATION TO SECTION ALLOWABLE AREA OF MIXED OCCUPANCY BUILDINGS. VERTICAL AND HORIZANTAL RATIOS.

2007 CHANGES  ADDITIONAL LANGUAGE TO SECTION GROUP A OCCUPANCY LOCATED IN UNLIMITED AREA BUILDINGS.. FOUR CONDITIONS.  ADDITIONAL LANGUAGE TO REDUCE OPEN SPACE FOR UNLIMITED AREA BUILDINGS

2007 CHANGES  MODIFICATIONS TO SECTION THAT DEAL WITH GROUP H OCCUPANCIES IN UNLIMITED AREA BUILDINGS.  CLARIFICATIONS TO SECTION INCIDENTAL USE AREAS  CLARIFICATIONS TO SECTION MIXED OCCUPANCIES SEVERAL SUBSECTIONS MODIFIED/CLARIFIED  TABLE MODIFIED TO MAKE IT EASY TO USE

2007 CHANGES  MODIFIED  A NEW SECTION TO DEAL WITH GROUP B OR M THAT OCCUR BELOW AN OPEN PARKING STRUCUTRE

2009 CHANGES    503  504  505  506  507  508  509