Glossary of Commercial Real Estate Terms


Under-Floor Duct System

A system of ducts permanently located under floor surfaces to assist in the installation of telephone, computer and electrical wiring.

Usable Area

The floor space on a given building’s floor that can be used by a Tenant and/or is enclosed as an office suite. On a single Tenanted floor, usable office space is the gross square feet of floor space less the core services area (for example, elevators, fire stairs) and less the common area (for example, electric, telephone and janitorial closets, bathrooms).

Usable Square Feet

Often abbreviated as “USF,” see also Usable Area, above.


Vacancy Rate

A common statistic used by commercial real estate professionals, including Landlords, Asset Managers and brokers, it identifies the percentage of office, industrial or retail space that is unoccupied in a building, market (city) or submarket (sub area of a city).   Vacancy rates vary over time as Tenant’s lease or vacate space.  See also Absorption Rate.


Window Mullions

The divisions between windows, which can accommodate or accept Tenant walls or partitioning to create separations between private offices or rooms.

Work Letter

A document supplied by a Landlord which includes building standard Tenant improvements, plus any additional items, to be paid for by the Landlord or by the Tenant, with an indication as to which is responsible for each item. For a more detailed discussion, see Building Standard Work Letter

Working Drawings

All of the construction documents and blueprints, such as detail drawings, schedules, blueprints of wall placement, wiring diagrams, etc. that would permit the various construction disciplines to construct the desired office space (or buildings) accurately and completely. Working drawings include architectural drawings; mechanical systems drawings; electrical, telephone, and other wiring drawings, plumbing drawings and structural drawings.  Preliminary working drawings will have initial electrical, mechanical and other engineering requirements, specifications and capacities.



The identified portions of an office floor served by the heating, ventilating, air conditioning (HVAC) system and having separate thermostatic and temperature controls.

The Guidance Advantage

Guidance Corporate Realty Advisors provides corporate tenant / buyer representation services to corporate real estate users in the Denver metropolitan area including Boulder, Colorado. Guidance also provides these services in all major U. S. markets, as well as markets in Canada, Asia, South and Central America, and Europe.

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