Building Area Frontage Question
AnsweredI have a question regarding IBC Equation 52..
Where the code define "Sa", It said " the actual number of stories above grade plane, not to exceed 3".
What does it really mean? What if I have an occupancy B, Type II A, sprinkled building, which has an allowable number of 6. Can the "Sa" in this equation has to not exceed 3? Does that mean I can only have a max. 3 stories building, if i want to benefit from the frontage area increase.

Janice,
Refer to the definition given in code for "Sa":
My understanding is that you can have a higher building, up to 6 stories for your building type / method of fire protection, but the number of stories for the allowable area calc. can only use 4 of those.
The definition for 'Sa" states; "Use actual number of building stories above grade plane, not to exceed four", so you can only count 4 of those 6 allowable stories (taken from table 504.4) for use in the calculation.
As to building area increase due to frontage, that is a separate value "If", and is calculated in one of two ways (refer IBC 2015, 506.3.1, and 506.3.3). The main factors for this value are the widths of the public rights of way, and the lengths of the perimeter walls that face those rights of way (detailed definitions / calculations are in these sections, so you should look at those if you have questions).
Hope this helps.
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