Alteration Commercial

add+alt+rep B2403450 n accordance with Section 104.10 of the Construction Codes (Title 12 of the District of Columbia Municipal Regulations (DCMR)), SmithGroup hereby respectfully requests approval of the proposed modification of the following sections of the Construccion Codes as applied to the above-referenced project/permit. Original code section: DCBC Section 1026.2: The horizontal exit separation shall extend vertically through all levels of the building unless floor assemblies have a fire-resistance rating of not less than two hours with no unprotected openings. Requested modification: Since it is infeasible to provide vertically-aligned horizontal exits or provide two-hour fire ratings for the entire floor assembly, given the existing building conditions, the proposed design includes protecting the existing floor on each side of the horizontal exit for one column bay in both directions. This will provide two-hour fire-rated supporting structure for the horizontal exit and greatly reduce the likelihood of a single fire affecting both sides of the horizontal exit. 1) Are there specific individual reasons that make application of the code impractical? If yes, please explain. a. The exisng floor construction does not meet the indicated design criteria from the original building permit construcon documents. The original construcon documents indicated that the building would meet the construcon requirements for a Type IB building in accordance with the 1972 DC Building Code; this would suggest two-hour rated floor assemblies. Tesng of the exisng floor construcon, including core-drill samples to determine as-built thickness, suggests the actual fire-resistance rang for mulple floors is one hour. This includes several floors that require a horizontal exit in the proposed design. It is impraccal to demolish all exisng floors and replace them with the full two-hour rated construcon. The exisng structure also does not allow the horizontal exit separaon to extend through all levels of the building, making prescripve compliance technically infeasible. 2) Is the requested code modificaon in compliance with the intent and purpose of the Construcon Codes? a. The requested code modificaon follows the intent and purpose of the Construcon Codes. The intent and purpose of a horizontal exit separaon is to allow occupants to move to a safe space in the building where they have addional me for egress from the protected compartment. The purpose of aligning the horizontal exit on all levels when two-hour floor assemblies are not present is to reduce the likelihood of a fire burning to an adjacent floor, compromising the other side of a horizontal exit. By providing a two- hour rang one column bay for the floor assemblies above and below the proposed horizontal exit separaon, the likelihood of a fire burning through the floor on each side of the horizontal exit and effecvely bypassing the horizontal exit is greatly reduced, sasfying the intent of the code. Furthermore, this provides two-hour rated supporng construcon, so that failure of the floor assembly does not cause premature failure of the horizontal exit.