2.8         Use, Occupancy and Construction Types

2.8.1            Use Classifications

The following use classifications are used by the Office of the Fire Marshal for various airport spaces. In the case of unusual spaces, consult the Office of the Fire Marshal to determine the assigned use classification.

2.8.2            Existing Construction Types and Use Group and Smoke Separations

A.      The AHJ has determined the following Construction Types for the various portions of the BWI Marshall Terminal complex and the required Use Group and Smoke Separations:

B.      Upper Level Tenant Fire Separation Requirements

Tenant to tenant separation walls shall be 1 hour fire rated partitions. Tenant to public corridor separation walls can be non-rated partitions.

Example 1: Concourse Level

C.      Lower Level Tenant Separation Requirements

Use Group Separations:

Fire rated fire separation walls are required between adjoining tenant spaces and also between tenant spaces and service corridors serving multiple tenants. If separating Use Groups, the fire rated walls are required to extend tightly to the underside of the floor or roof deck above with all ductwork penetrations provided with U.L. listed, self resetting, electrically actuated fire dampers shall be installed and all wiring penetrations protected in accordance with a U.L. listed penetration protection design. Fire rated separation walls between Use Groups shall comply with the fire rating requirements of the IBC and shall be constructed of non-combustible materials. Tenant Separations, Same Use Group: Fire rated fire separation walls are required between adjoining tenant spaces and also between tenant spaces and service corridors serving multiple tenants. If ceiling-mounted area smoke detection is provided within the tenant spaces, the fire separation wall may terminate at the underside of a UL listed fire rated floor-ceiling Assembly. Fire rated separation walls separating tenants shall be one (1) hour fire rated and constructed of non-combustible materials.

Example 2: Lower Level – Fire Rated Partitions

Note: Where a one (1) hour fire rated tenant separation is required for a new tenant that could potentially disturb an existing adjacent tenant space, the new tenant space may be separated in accordance with Figure 1 or Figure 2 below, an alternate U.L. listed one (1) hour rated assembly. In such case, the fire separation partition shall extend on either the ceiling or to the deck above, as appropriate per Paragraph 7 above.

Figure 1– Condition where ½” drywall is on one, or both, sides of an existing tenant separation partition and does not currently provide a 1 hour rating without additional GWB liner panel being installed.

Figure 2– Condition where 5/8” “Fire Code” drywall existing on only one side of the tenant separation partition and a gypsum liner panel is installed to completed the required separation.

2.8.3            Procedures for Determining Occupancy Loads and Minimum Required Egress Capacities for Concourses

A.      Overview

This Policy shall be used in the planning and construction of all new Concourses, and in modifications or expansion of existing Concourses at BWI Marshall that affect egress capacity or occupant loads. It also applies to all future terminal development involving Concourse egress. It is intended to provide consistent and documented methods established by the Fire Marshal as the Authority having Jurisdiction (AHJ) for fire code enforcement at BWI Marshall Airport.

B.      Egress and Occupant Loads:

1.       An emergency egress plan from tenant spaces is required.

2.       All travel distances from the Concourses must be taken to the non-secure side of the Security Checkpoint or to the nearest stairwell.

3.       The occupancy load for each tenant space must be calculated and shown on the plans.

4.       A performance based “Life Safety Evaluation”, developed in accordance with NFPA 101, is required for all projects serving an occupant load of more than 6,000 persons. Significant alterations or additions to existing spaces may be required to comply. Check with the Office of the Fire Marshal regarding your project. A Professional Engineer who is licensed to practice in Maryland, and who is a Fire Protection Engineer, must prepare the Life Safety Evaluation.

C.      Emergency Egress Capacity Requirements

Emergency egress capacity requirements for Concourses A and B are based on the Model Codes (NFPA 101, IBC), except as modified in the CHECCG. A Fire Protection Engineer, who is a licensed Professional Engineer in the State of Maryland, shall prepare any such required egress capacity and occupant load calculations, with supporting justification, for review of the Office of the Fire Marshal for any modifications or expansions of a Concourse that affect egress or occupant loads.

The following criteria shall be followed when evaluating Emergency Egress Capacity:

1.       Egress components from Concourses must be sized to provide at least 50% of the Concourse occupant load through the front/main exit. The main/front exit of the Concourse is considered the egress route into the Terminal Building. Egress via an adjacent secure corridor that connects Concourses may also be considered contributing to the front/main exit egress capacity provided that the secure corridor leads to egress to the Terminal building or to a space designed to meet the requirements of NFPA 101, most recent adopted Edition, for “Horizontal Exits”.

2.       Egress components from Concourses must be sized to provide at least 100% of the Concourse occupant load through the Concourse egress stairs to the airfield-side apron to accommodate an incident that could block the front/main exit. The Fire Marshal has determined that a potential exists for an incident rendering the front Concourse exits possibly inaccessible or no longer well defined during the incident.

a.       Exception 1: In existing Concourses, where 100% occupant load egress stair capacity is not currently provided, upgrading the stair capacity to achieve 100% capacity is not required unless the Concourse footprint is being increased in area.

b.       Exception 2: In existing Concourses, where 100% occupant load egress stair capacity is not currently provided, upgrading the stair capacity to achieve 100% capacity is not required if the Concourse area is being increased in order to improve existing deficient egress via the required front exit (as per paragraph A above).

A.      If there are more stringent egress requirements of the IBC, they shall apply.

2.8.4            Procedures for Holdroom Sizing

Refer to Volume 5, Chapter 1 Concourse Holdroom and Egress Code Compliance.

2.8.5            Occupant Capacity Calculations

OFM will need to obtain square footage calculations to determine occupant load capacity numbers.  These numbers will require the gross and net floor areas to be provided to OFM.  The gross floor area is within the inside perimeter of the outside walls of the building or area under consideration with no deductions for hallways, stairs, closets, elevators and building service shafts, or other features, but excluding floor openings associated with atriums and communicating shafts.  The net floor area is the actual occupied area not including unoccupied accessory areas such as corridors, stairways, ramps, toilet rooms, mechanical rooms, closets, wall cavities and columns.  The consultant shall provide OFM with both gross and net floor area calculations.