Finger Lakes Building Officials, Inc.

An Affiliated Member of the New York State Building Officials Conference

June 12, 2003

RE: Thumb latches on mercantile building
BC 1003.3.1.8

This is in response to your questions regarding the use of thumb latches on a building of mercantile, M occupancy classification. Thumb latches are not permitted on the doors of a mercantile occupancy. They are only permitted for individual dwelling units (see BCNYS section 1003.3.1.8 exception 4, below). Egress doors in mercantile occupancies are permitted to be equipped with key-operated locking devices on the egress side with certain provisions. (see BCNYS section 1003.3.1.8 exception 2, below).

Building Code of New York State (BCNYS) section 1003.3.1.8, Locks and latches, provides that egress doors shall be readily openable from the egress side without the use of a key or special knowledge or effort, with the following exceptions:
1. Places of detention or restraint.
2. In buildings in occupancy Group A having an occupant load of 300 or less, Groups B, F, M, and S, and in churches, the main exterior door or doors is permitted to be equipped with key-operated locking devices from the egress side provided:
2.1. The locking device is readily distinguishable as locked,
2.2. A readily visible durable sign is posted on the egress side on or adjacent to the door stating: THIS DOOR TO REMAIN UNLOCKED WHEN BUILDING IS OCCUPIED. The sign shall be in letters 1 inch (25.4 mm) high on a contrasting background,
2.3. The use of the key-operated locking device is revokable by the code enforcement official for due cause.
3. Where egress doors are used in pairs, approved automatic flush bolts shall be permitted to be used, provided that the door leaf having the automatic flush bolts has no doorknob or surface-mounted hardware. The unlatching of any leaf shall not require more than one operation.
4. Doors from individual dwelling units and guest-rooms of Group R occupancies having an occupant load of 10 or less are permitted to be equipped with a night latch, dead bolt or security chain, provided such devices are openable from the inside without the use of a key or tool.

You also ask about the applicability of ICC/ANSI A117.1 - 1998, Accessible and Usable Buildings and Facilities, section 402.2.7, Door Hardware. The exception, "Locks used only for security purposes and not for normal operation are permitted in any location" is applicable to the key-operated lock described in BCNYS section 1003.3.1.8 exception 2.

This advisory opinion is rendered based upon the information provided. Administration and enforcement of the code are within the jurisdiction of the local authority. If you have questions regarding this advisory, please call me at (518) 474-4073.

Sincerely,
Cheryl A. Fischer, P.E.
Assistant Director for Code Interpretation
Codes Division
Al03-085

Finger Lakes Building Officials Association, Inc.
3100 Atlantic Ave.
Penfield, NY 14526