Gross Area and Exterior Spaces - When/what to include? and What about area Conversions?


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    Eugene O'Callaghan

    Area definitions are not always consistent so I generally approach it from the opposite direction - what is the question functionally asking, and this usually points me in the right direction for a definition.

    Height & area questions for an initial code check of a building massing study - IBC Building Area.

    Occupancy load questions - could be IBC Floor Gross Area or Net Area - depends on the multiplier for the function of the space.

    Construction cost questions - gross area to exterior face exterior walls usually. Could be usable area if it's an interior fitout cost question.

    Building efficiency or usable area questions - BOMA area definitions.

    Lot coverage, parking ratios, interior & exterior courts - probably a Zoning Code question, if so there's no consistency at all in area definitions, so they should provide the definition in the question or case study reference material.

    To answer your specific questions - exterior plazas would not be considered part of IBC Building Area except for the portion covered by a roof eaves or floor projection (if any). The majority of instances where this comes up in practice are projecting balconies - that's my basic heuristic for it. Exterior plazas would primarily be dealt with in the Zoning Code (lot coverage etc) but may be relevant to some specific building code questions like an area bonus for frontage.

    Is the dumpster question related to cost? That's where it might be counted as gross area. If it's a code question, I would think (off the top of my head) it's a Group S or Group U separate building, so they're maybe asking about allowable area or fire separation. There should be some clue in the question or the case study resources.

    TLDR; for ARE purposes figure out what the question is functionally testing you on, and that should point you towards the most likely relevant area definition. I find that more reliable than trying to memorize area definitions in detail.

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