Interpretation #6872

Original Request

Code Version: 2007
Code: EXTBLDG
Code Description: Existing Building
Chapter: 8
Section: 807.5.2
Topic: Substantial Structural Alteration

Question

Is it the intent of 807.5.2 (807.5.2 Substantial structural alteration. Where more than 30 percent of the total sum of floor and roof areas of the building or structure has been or is proposed to be involved in structural alteration within a 12-month period, the evaluation and analysis shall demonstrate that the altered building or structure complies with the Florida Building Code, Building for wind loading.) when calculating the total sum of floor and roof areas of a building the two areas are separate and not combined? Example: Single story stand alone building, floor sf of 4000 square feet with wood trussed roof structure. Roof structure with overhangs equals 4400 sf. Under 807.5.2 do we combine the floor sf of 4000 sf with the roof structure sf of 4400 to equal the total sum of 8400.

Answer Published 12/21/2011 at 2:25 PM

No do not combine the two unless the roof structure is
being altered as well as the area under the roof. In other
words, if the roof is not being structuraly altered do not
add the area of the roof to the calculation.

Commentary

The 2009 IEBC (2010 FBCEB) provides guidance as to what is counted toward the 30 percent calculation: "The areas to be counted toward the 30 percent shall be those areas tributary to the vertical load-carrying components, such as joists, beams, columns, walls and other structural components that have been or will be removed, added or altered, as well as areas such as mezzanines, penthouses, roof structures and in-filled courts and shafts."