!st Review 1/23/2014 - Correction Required.

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1.  The Code Analysis states" an enclosed elevator lobby is required" then references exception 5 refering to smoke partitions in lieu of the 1 hour partition when sprinklers are provided.  You then state the existing partitions are not smoke partitions because they do not extend above the ceiling grid.  If this is true then exception 5 does not apply.  You reference IEBC 703.2.2 and infer that because the work area is less than 50% of the floor an existing noncompliant condition can remain because it does not reduce the level of protection of the lobby walls.  I disagree with this interpretation to include your code path.  If you have a specific clear interpretation and/or other code path please provide such.

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Since this is a Level 2 Alteration IEBC 703 applies.  IEBC 703.2 requires compliance with the provisions of 703.2.1, 703.2.2 and 703.2.3.  703.2.1 requires a 1 hour separtion.  None of the exceptions are applicable, especially number 5 which would allow a reduction to 30 minute providing the vertical opening does not exceed 3 stories.  IEBC 703.2.2 does not apply but also does not allow you to disregard IEBC 703.2.1.  IEBC 703.2.3 applies to stair enclosures and not the lobby.

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Note:  Comment Resolved @ counter by AFM Hill.  Per contractor and building owner rep the shaft is pressurized.  Plans redlined @ counter and approved by Cleo Hill