IBC Area Increase Modifications Calculator

Calculate allowable area increases for frontage and sprinkler modifications per IBC Section 506.2.

Input Parameters

Results

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Frontage Increase (If)
%
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Sprinkler Increase (Is)
%
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Modified Allowable Area
sq ft
--
Total Area Increase
%
Note: Area increases are cumulative. The frontage increase requires at least 25% of the perimeter on a public way or open space with minimum 20 ft width. The sprinkler increase of 200% applies to multi-story buildings with NFPA 13 systems; single-story buildings may receive up to 300%.

Reference

IBC Section 506.2 Area Modifications: Aa = At + (At x If/100) + (At x Is/100) Frontage Increase (If): [(F/P - 0.25) / 0.25] x (W/30) x 100 F = frontage on public way, P = perimeter, W = setback width (min 20 ft) Sprinkler Increase (Is): NFPA 13: 200% (multi-story), 300% (single-story) NFPA 13R: 100% None: 0%