According to the Building Owners and Managers Association (BOMA) standard ANSI/BOMA Z65.1, Usable Area on a multi-tenant floor is the actual space occupied by and for the exclusive use of a tenant. It is measured to the office-side of common corridor walls and to the inside finished surface of the exterior walls. In the provided floor plan, the spaces labeled "Tenant 1" and "Tenant 2" are the only areas designated for exclusive tenant use. The elevator lobby, restrooms, and electrical/telephone closets are considered Building Common Areas, which are shared by tenants and are used to calculate the Rentable Area, not the Usable Area.

B. Incorrectly includes the Elevator Lobby, which is a Building Common Area used by all tenants on the floor, not part of the exclusive Usable Area.

C. Incorrectly includes the Electrical/Telephone room, which is a Building Service Area (a type of Building Common Area) and not part of the tenant's Usable Area.

D. Incorrectly includes both the Elevator Lobby and the Electrical/Telephone room, which are both classified as Building Common Areas under BOMA standards.

1. BOMA International. (2017). BOMA 2017 for Office Buildings: Standard Methods of Measurement (ANSI/BOMA Z65.1-2017).

Section 2.2

Usable Area: Defines Usable Area as the space measured for the exclusive use of an occupant.

Section 2.3.4

Building Common Area: Defines areas such as lobbies

corridors

restrooms

and mechanical/electrical rooms as common areas that are not part of the Usable Area.

2. University of Washington

College of Built Environments. (Course Material for RE 513 - Real Estate Development). Lecture on BOMA Standards.

The courseware explains the hierarchy of space measurement

clearly distinguishing Usable Area (the tenant's exclusive space) from Floor and Building Common Areas (lobbies

janitor closets

restrooms)

which are factored into the Rentable Area through a load factor.

3. Grimley

C.

& Love

M. (2018). The Interior Design Reference & Specification Book: Everything Interior Designers Need to Know Every Day. Rockport Publishers.

Chapter 1

"Fundamentals

" Section on "Calculating Square Footage" (pp. 30-31): This text

commonly used in university interior design programs

explains that BOMA defines usable square footage as the area the tenant actually occupies

explicitly excluding shared common areas like lobbies

corridors

and service closets on multi-tenant floors.