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IBC 2006-2009 Allowable Area Calculator

Jonathan Ochshorn

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Directions: Enter values for occupancy classification, construction type, sprinklers, and proposed number of stories, as well as building perimeter lengths and distances from building to property lines. Choose 2006 or 2009 International Building Code (IBC). Press "update" button.

Based on the 2006 or 2009 IBC, values are calculated for allowable areas, heights, and numbers of stories. The site plan (Fig. 1) corresponds to the default values indicated below for a proposed 4-story, unsprinklered office building (occupancy class = B) of type III-A construction. Distances may be measured from the building to the far side of a "right-of-way" [R.O.W.], as is shown for the building perimeter facing east. In this case, the distance is 35 feet. Some occupancies require sprinklers under certain circumstances: see notes immediately below calculated values for details.

Notes and clarifications:

For more information, see my online building code handout.

site plan with yard dimensions
Fig. 1. Site plan showing yard and building dimensions.
 

Building information:   Notes:  
Occupancy classification:    
Construction type:    
Sprinklered?    
Proposed number of stories:    
  Building perimeter lengths (ft)   Distance to property line or to far side of R.O.W. (ft)    
       
       
       
facing north:      
       
       
           
facing east:      
       
       
           
facing south:      
       
       
           
facing west:      
     
     
   
Code version:   1. Proposed number of stories <= allowable number of stories.
    2. Proposed number of stories is positive integer.
Allowable Areas and Heights:   3. Sprinkler type NFPA 13R can only be used with group R occupancy
Allowable area per floor:   4. Building perimeter lengths and distances cannot be negative.
Total allowable area:   5. Values for both building perimeter and distance must be entered
Maximum allowable height:  
Maximum allowable stories:  
  8. Combination of occupancy and construction type not permitted in Table 503
 
  Warnings:  
  1. NFPA 13D sprinklers may be installed in 1-2 family dwellings per Sec. 903.3.1.3  
  2. Unlimited area possible with yards of 40+ ft around 75% of building, per Sec 507.5 (not calculated here)  
  3. Unlimited area possible with 1-story, A-3 (some restrictions), Type II, NFPA 13 sprinklers, 60 ft yards, per 507.6 (not calculated here)  
  4. Sprinklers required with group A, E, F-1, H, I, M, and S occupancies per Sections 903.2.1 - 903.2.9 as well as in other conditions.  
  See notes to the left.  
  5. Sprinklers required with group R occupancies per Sec. 903.2.7.  
     
    7. Where NFPA 13 sprinklers substitute for 1-hr rating, exterior walls must still meet Table 601 and 602 requirements.  
   
  9. Other limitations and exceptions may apply; see IBC for details.