Floor Common Area. Floor common area includes
toilets/washrooms, janitorial closets, electrical rooms,
telephone rooms, mechanical rooms, elevator lobbies, and
public corridors that are available primarily for the joint
use on that floor. Note that this will vary floor to floor
based on public corridor configurations. For single-tenant
floors, corridor and lobby spaces may be included in the
office or store usable area because they will be for the
exclusive use of that floor's only. On main ground floors,
floor common areas would only include corridors created
because of store area configuration and telephone, janitor
closet and electrical closets added because of the addition
of store area on the ground floor.
Floor R/U Ratio. Floor R/U ratio gives the basic rentable
area. It is calculated by the following formula:
Floor Rentable Area/Floor Usable Area = Floor R/U Ratio
Note that this ratio will vary from floor to floor based on
public corridor configurations.
Oakland Federal Building, Oakland, CA
Floor Rentable Area. Floor rentable area is the gross
measured area minus the exterior wall and major vertical
Floor Usable Area. Floor usable area is the sum of all
penetrations. Floor rentable area is calculated by:
office, store and building common usable areas. Floor
(sum of Office and Store Usable Areas on
usable area is the floor rentable area minus floor common
the floor) X Floor R/U Ratio = Floor Rentable Area
areas which are available primarily for the joint use of
tenants on that floor.
It is also equal to the sum of the basic rentable areas for
that floor. Full floor tenants will be assessed the gross
Gross Building Area or Constructed Area. Gross building
measured area of a floor minus building common spaces as
area or constructed area is the total constructed area of a
their floor rentable area. Note that because it includes
building. It is measured to the outside finished surface of
building common area, floor rentable area is not
permanent outer building walls, without any deductions.
necessarily indicative of space demised for a single
This is the area GSA budgets for construction purposes.
tenant's use.
Gross Measured Area. Gross measured area is the total
area within the building, minus the exterior wall.
56 F A C I L I T I E S S T A N D A R D S
FOR THE
PUBLIC
BUILDINGS
SERVICE
3.1 Basic Building Planning Principles
Revised March 2005 PBS-P100
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