BAM Building Area Measurement LLC

Glossary of Square Footage Terms

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Here are definitions of 250 terms used (and misused) in the measurement of floor area in buildings. Varying standards use different rules for classifying space and for determining the boundaries of each class of space. Therefore, measurements performed under different standards will yield different figures. Please refer to individual published standards for specifics.

The degree of conformity of a measured or calculated quantity to its actual, absolute value. In building area measurement it is the degree of conformity of a floor area measurement to the actual floor area. See also Precision, Tolerance and Variance.
A measure of area most often applied to land equal to 43,560 square feet or 4,046.86 square meters. A square mile contains 640 acres.
Add-on Factor
Another term for the BOMA R/U Ratio, not defined in the BOMA Standard.
A change to construction documents made after they are issued for bidding but prior to award of the construction contract, often in response to questions by bidders. Changes made by addenda may be reflected in record drawings.
The American Institute of Architects, with URL www.aia.org.
AIA Standard
Methods of Calculating Areas and Volumes of Buildings, AIA Document #D101-1995 (current version) published by the AIA.
The American Industrial Real Estate Association, with URL www.airea.com.
AIR Standard
The AIR Industrial Building Standards, a set of five standards for floor area measurements of industrial buildings, published in March, 1993 by SIOR and used as a basis for the BOMA Industrial Measurement Standard which supplanted it in October of 2004.
The American National Standards Institute, the major standards organization in the United States and publisher of the BOMA Standards, the NAHB Residential Standard, and ISO 9836 International Standard, with URL www.ansi.org.
A level of accuracy that is inexact or incorrect. Unless a Tolerance is explicitly indicated, "approximate" can mean anything from "as accurate as possible with professional application of normal measuring technology" to "wild-ass-guess from pacing the area". In parts of Canada this level of accuracy is statutorily defined as plus-or-minus 25%.
Architectural Area
A term used and defined in the AIA Standard primarily for the purposes of construction cost estimating. Many of the standard estimating references employ this measure of floor area.
As used in building area measurement, the quantitative measure of a horizontal two-dimensional plane expressed in Square Feet or Square Meters, bounded by lines relating to building walls or classes of space as determined by measurement standards or practices.
Area, Building
See Building Area.
As-built Drawings
Graphic depictions of a building on paper or CAD that, in theory, reflect precisely the actual construction of every part and system of a building. A perfect set of as-built drawings is generally infeasible due to the cost of documentation. See Record Drawings.
Assignable Area
A term used in the IFMA Standard to measure space assigned to tenant personnel, furniture, equipment support areas and common support areas, not including secondary circulation within tenant’s Usable Area.
The American Society for Testing and Materials, a U.S. standards organization that publishes the IFMA Standard, with URL www.astm.org.
See PBS Business Assignment Guide below.
An acronym for Building Area Measurement, LLC, a firm that provides consulting, training, and dispute resolution services related to building area measurement standards and practices throughout North America, serving property owners and managers, tenants, lenders, realtors, attorneys, appraisers and design professionals, with URL www.BuildingAreaMeasurement.com.
Basic Rentable Area
A BOMA term signifying the result of multiplying the Floor Usable Area of a floor, suite or Building Common Area, by the Floor R/U Ratio. An intermediary figure not directly used in leasing.
1.-A systematic measurement error representing the difference between the average or expected value of a measurement sample and the true value of the measurement. Ways to introduce bias into field measurements include not measuring horizontally and allowing measuring tapes to sag excessively.
2.-A departure from objectivity. Those who are focused on the interests of a landlord or tenant can be biased in their application of a measurement standard, which can lead to a measurement dispute.
BIM Area
A term used by the US General Services Administration Public Building Service and defined as the area bounded by the inside face of surrounding walls, minus the area bounded by the outside faces of any contained full height columns. See the GSA BIM Guide
Building Information Modeling, an enhancement to CAD that allows the construction of a virtual building in a computer. When complete, the computer is aware of the characteristics of the virtual building including its Usable and Rentable Areas.
The Building Owners and Managers Association, publishers of and secretariat for the BOMA Office and Industrial Standards. Their URL is www.boma.org.
BOMA Standard
Either the Standard Method for Measuring Floor Area in Office Buildings or the Standard Methods for Measuring Floor Area in Industrial Buildings, depending on the occupancy of a property. It is clearer to refer to the BOMA Office Standard or the BOMA Industrial Standard, and clearer yet to specify the publication year. The Office Standard in particular has been modified and re-published many times and is likely that the Industrial Standard will be also.
Building Area
Section 502.1 of the International Building Code defines this term as the area included within surrounding exterior walls (or exterior and fire walls) exclusive of vent shafts and courts. Areas of the building not provided with surrounding walls shall be included in the building area if such areas are included within the horizontal projection of the roof or floor above.
Building Code
A local statute that governs the design and construction of buildings. In most jurisdictions, building codes require a Certificate of Occupancy, or CO, before a building can be legally occupied. Although one would think that all rented space meets the requirements of building codes for occupancy, there are no such requirements in any current major measurement standard.
Building Common Area
Fully enclosed space within a building that benefits all occupants of that building but which does not accommodate a tenant's personnel, furniture, fixtures or equipment. The usual example is the first floor building entry lobby. It may include additionally spaces like the building engineer’s office, building HVAC areas and loading docks. See individual measurement standards for definitions.
Building Core and Service Area
Term used in the IFMA Standard to describe Floor Common Area excluding corridors on multi-tenant floors. See also Core Space.
Building Line
Actual: A horizontal line forming a perimeter that encompasses all the constructed elements of a given floor of a building and other areas covered by a roof. Non-structural protrusions, including eaves, cornices, canopies, awnings, sills, ledges, casing, wainscoting, gutters, downspouts, signs, shutters, attached electrical or mechanical systems or decorative projections, are ignored.
Statutory: A line or plane established by zoning or building codes as a limit to buildable area or volume of a building.
Computer Aided Drafting - Software enabling the execution of drawings on a computer to a much higher degree of accuracy than it is possible to build in the field while still fudging dimensions critical to a metrologist, like the location of the inside face of exterior glass. In real estate, it is also an acronym that stands for Cash Available for Distribution.
Computer Aided Facility Management – Software that can contain some features of CAD that automate aspects of facility management. Most CAFM packages focus more on non-graphic aspects of facility management.
To check and adjust the accuracy of a measuring instrument relative to a reliable standard. A measuring tape that has been used a lot or damaged should be calibrated against a new one or by a laboratory that is certified by the NIST. Lasers and other DME come with manufacturer’s instructions for calibration that should be followed, with records maintained in case a question arises.
Campus Common Area
Fully enclosed space in a group of buildings that benefits all the occupants of that group of buildings without being used exclusively by any one occupant. An example might be a HVAC plant that heats and cools all buildings, or a cafeteria or auditorium shared by occupants of a group of buildings.
Campus R/U Ratio
When multiple buildings share common elements (see Campus Common Area) the Campus R/U Ratio is used to allocate the floor area of those common elements to the Rentable Area of each tenant. It is also referred to as a Site R/U Ratio or Multi-building R/U Ratio.
Ceiling Tile Count
A method of roughly measuring floor area by counting ceiling tiles and multiplying by the area of each tile. This can be a more accurate way of measuring area than by Pacing but generally not accurate enough to be used for leasing or appraisal.
To guarantee as true. A measurement or area calculation that is certified is presumably more reliable than one that is not, depending on the credentials of the entity that provides the certification. For design professionals, certification gives rise to contractual liability that is not covered by standard E&O insurance policies.
Change Order
A change in construction dimensions or materials issued after the contract for construction has been awarded but before construction has been completed. Change orders may have an impact on floor area measurements and are sometimes reflected in record drawings when the contractor produces them.
See Common Interest Community
see Common Interest Ownership Act.
Circulation Factor
Used in conjunction with a Space Requirements Projection, this factor is the result of dividing is Secondary Circulation by Usable Area. It is applied to Assignable Area to calculate required Usable Area. Care must be taken in application of a Circulation Factor. For example, if the Circulation Factor is 25%, do not multiply Assignable Area by 1.25. Instead, divide it by 0.75 (Rule: divide by the compliment).
Circulation Space
Corridors, aisles and other similar space required for occupants to access means of egress and all other functions in and serving their space. Circulation may be classified as either primary, secondary or tertiary, and it may be fully enclosed as in a corridor, or unenclosed, as in a phantom corridor (a term coined by Willie Pena).
Chargeback System
A system for allocating total occupancy costs to individual company departments, divisions or other groups based upon the square footage they occupy and their actual costs.
Cleanable Area
The actual surface areas of floors, walls, windows, sills, furniture, fixtures and equipment that require cleaning in order to maintain sanitary conditions and good appearance. May or may not have any relationship to other measures of floor area used in leasing.
Coefficient of Expansion (Thermal)
The rate of change in the size or length of a building component or a measuring tape caused by a given change in temperature. A steel building 200' long without expansion joints will be 5/8 inch bigger at 75 degrees Fahrenheit than it is at 35 degrees. A steel measuring tape likewise changes length with temperature change, but distance measured by a LDM does not.
Common Area
In commercial properties, fully enclosed space in a building that benefits others in the building but does not accommodate tenant’s personnel, furniture, fixtures or equipment. It is usually classified as either Building Common Area or Floor Common Area. Limited Common area is also seen in certain building designs, and Campus Common area can exist within a group of related buildings. Appraisers and attorneys may apply this term to parking lots, exterior plazas, sidewalks, and the like, but its use in the context of building measurement applies only to fully enclosed space. A space cannot be counted as both Common Area and Usable Area.
Common Elements
In Common Interest Communities, any elements that are not part of the Units. This may include exterior elements in addition to enclosed spaces, and encompasses both General Common Elements and Limited Common elements.
Common Area Factor
Another term for the BOMA R/U Ratio, not defined by the BOMA Standard.
Common Interest Community
A form of real property ownership that includes condominiums, cooperatives and planned communities that may be regulated by state statutes such as condominium acts or common interest ownership acts, some of which contain explicit definitions of unit boundaries that are relevant to the measurement of their floor areas.
Common Interest Ownership Act (CIOA)
Common Interest Ownership Acts are state statutes that govern Common Interest Communities and may contain explicit definitions of unit boundaries that are relevant to the measurement of their floor areas. See also Declaration.
A form of property ownership in buildings with multiple occupants wherein each occupant owns a defined unit along with an undivided interest in the common elements, which include building structure, enclosing and demising walls, hallways, lobbies, mechanical rooms and the like. Condominium ownership can apply to both residential and non-residential uses. Unit boundaries in residential condos are often defined by state statute. See also Common Interest Community.
Construction Area
A term used in the 1980 BOMA Standard and not well defined therein. It was replaced in the 1996 BOMA Standard by the term Gross Building Area. See also Architectural Area.
Construction Documents
Collectively, the working drawings, specifications, general conditions, addenda and instructions to bidders that for the basis of a construction contract. They are sometimes referred to as CDs, but so are Construction Drawings. Does not include RFIs or Change Orders.
Construction Drawings
See Working Drawings
Contractual Liability
Liability that arises out of certain written statements by design professionals, such as certification of area calculations, which may be excluded from coverage under professional Errors and Omissions (E&O) insurance. Separate contractual liability coverage is often required to cover certification of area calculations.
Conversion Formula
A term used in ANSI/BOMA Z65.1-1980 to describe the relationships between the Rentable Area of a floor, its Usable Area and its R/U Ratio. The term was discontinued in ANSI/BOMA Z65.1-1996.
Core Factor
Another term for R/U Ratio or Loss Factor, used by the GWCAR Standard.
Core Space
Collectively, the spaces which serve the usable areas of a floor but which generally are not themselves usable area. Core space includes fire stairs, elevator shafts, toilets, janitor’s closets, machine rooms, HVAC shafts, electrical and telephone closets. Core space may be aggregated in a “center-core” or “side-core” building layouts, or dispersed in “multi-core” layouts. Buildings with defined core areas may have space within the core area that is usable for tenant storage, communications equipment, work rooms and the like. Elevator lobbies are generally considered usable area for full-floor tenants.
Cubic Foot
A volumetric measure of space equal to the volume contained in a cube measuring 12 inches in length, width and height. Cubic footage is important in HVAC system design and warehouse buildings but is generally not used in real estate. However, it has recently been seen along with price per cubic foot in listings for some high-end residential condos in New York and London.
A unit of length, about 17.7 inches, used in construction of The Pyramids, not generally used in commercial real estate today.
Data Tag
A device use in CAD and BIM systems to display data about a building element like a delimited portion of floor space. A data tag might include the space ID (SPID), square footage, space type and occupant information.
DC Standard
See GWCAR Standard.
Declaration (CC&Rs)
Also called Covenants, Conditions and Restrictions, it is a set of private documents used in Common Interest Communities that includes the Map that documents the boundaries (including lower and upper horizontal planes in the case of a multi-story building) of each unit and all common elements. The Map must be stamped by a licensed land surveyor in most states, although some states permit a map to be stamped by a licensed architect.
Demising Line
A legal term derived from the French word demise (to give away) describing a boundary line encompassing floor area (demised area) within which tenants or condominium owners possess certain rights to the use or possession of space.
Demising Wall
A wall that contains a Demising Line. The demising line may be located on either face, the centerline, or in some other location (like Dominant Portion) within the wall, depending upon wall location, measurement methodology or standard cited.
A metric for office space utilization measured in square feet per person. The measure of square footage is usually Usable Square Feet, but is occasionally Rentable Square Feet. You don't know until you ask.
Design Gross Area
A term used by the General Services Administration Public Building Service in their Business Assignment Guide and defined as the total constructed area of a building measured to the outside dominant finished surface and including all enclosed floors of a building including sub-grade levels, mechanical floors, penthouses, structured parking and crawl space.
Destructive Measurement
The act of creating openings in walls by boring or sawing holes to permit inspection of hidden surfaces or enclosed spaces for the purposes of classifying space and determining field dimensions to space class boundaries.
Acronym for Deutsches Institut für Normung, the German supra-national standards organization with an English URL at www2.din.de/en. They publish a floor measurement standard DIN 277 used in Germany.
Distance Measuring Equipment, usually laser-based, such as the Leica Disto or Hilti Handheld Range Meter, suitable for the accurate field measurement of buildings if used by a trained Metrologist. See also LDM.
Dominant Portion
A term used differently by various standards to identify the surface of a wall that constitutes the boundary of a floor area for measurement purposes. See individual standards for detailed definitions.
Drip Line Method
A method of measuring Industrial Space defined in the BOMA Industrial Standard as Method B.
(1) Rental efficiency of a building is its Rentable Area divided by its Gross Area. Rental efficiencies of tall office buildings have in creased over time from 69% for the Empire State Building, (New York City, 1931) to 85% for Republic Plaza, (Denver, 1980). Industrial and retail buildings often have rental efficiencies of 100%, meaning that they are leased using their Gross area.
(2) Planning Efficiency of a building or floor is its Usable (or Plannable) Area divided by its Rentable Area, the inverse of the R/U Ratio. Planning efficiencies vary depending on whether a floor is constructed for a single or multiple occupants.
(3) Programming Efficiency is the Assignable Area of a tenant or occupant divided by the Gross area (or Usable or Rentable Area). See definition of Tare Area.
Errors and Omissions Insurance
Insurance carried by design professionals covering malpractice, including making mistakes in building area measurements and area calculations. It is often referred to as E&O insurance, professional liability or malpractice insurance and is highly recommended for design professionals who do floor area measurements that are the basis for commercial transactions.
A base building element that is part of the usable area of a floor but inhibits its use for furniture and equipment. Examples include window sills, columns, wall-mounted heating & cooling units and low headroom conditions under pipes, ducts or structure. Encroachments are not measured by some property management standards (BOMA, REBNY) but may be under facility management standards (like IFMA).
A web-based distance learning tool that contains a learning module on the BOMA Standard. The URL is www.ebridge.tv/boma/measurement/.
Facility Usable Area
From the IFMA Standard, fully enclosed space, excluding encroachments, that is available for the exclusive use of a building occupant for occupant’s personnel, materials, furniture, fixtures, and equipment. This term may be changed in the future to Plannable Area. See also Usable Area.
Field Dimensions
Dimensions determined on-site in a building using a measuring tape or LDM. Field dimensions are usually made to apparent building elements and often require adjustment to determine the boundaries of classes of space for the purpose of doing lease area calculations.
A class of computer software that assists in development of floor plans on portable computers with CAD software, often connected directly to laser distance meters, without the necessity of bringing the work back to an office for additional processing.
Finished Area
As used in the NAHB Residential Standard, an enclosed area in a house that is suitable for year-round use, embodying walls, floors and ceilings that are similar to the rest of the house.
Finished Surface
In the BOMA Standard, it is the surface of a wall, floor or ceiling as prepared for tenant use but excluding the thickness of any special tenant finishes such as paneling or carpeting. Naked studs without gypsum wall board applied are not a finished surface, but concrete or masonry units might be.
Flex Space
Space with attributes suitable for occupancy either by offices or light industrial/warehouse operations. Such space might be measured for leasing employing either a office or industrial measurement standard at the option of the owner/landlord.
An enclosed horizontal division of a building characterized by a structural surface capable of supporting loads imposed upon it by occupants. It is sometimes referred to as a "story". See also "Interstitial Space".
Floor Area, Gross
Section 1002.1 of the International Building Code defines this term as being "The floor area within the inside perimeter of the exterior walls of the building under consideration, exclusive of vent shafts and courts, without deduction for corridors, stairways, closets, the thickness of interior walls, columns or other features. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal projection of the roof or floor above. The gross floor area shall not include shafts with no openings or interior courts." NPFA-101 has a different definition and some local building codes also depart from this measure in some respects.
Floor Area, Net
A term used in building codes to describe the actual occupied area of a floor, not including accessory unoccupied areas (stairs, elevator & HVAC shafts, mechanical rooms, etc.) or the thickness of walls. See NPFA-101 page 17, the International Building Code section 1002.1, or your local building code.
Floor Area Ratio (FAR)
The floor area of a building expressed as a ratio of the area of the site. Zoning codes often establish a maximum FAR for buildings in certain locations. Some jurisdictions grant bonus FAR in return for certain amenities provided by a building to its neighborhood. Floor area for this purpose is sometimes called Zoning Floor Area (see definition). See also Transferable Development Rights.
Floor Common Area
Fully enclosed space on a floor that benefits all occupants of that floor but does not accommodate the tenant's personnel, furniture, fixtures and equipment. The usual examples are toilets, janitor’s closets, electrical closets and HVAC equipment rooms serving only the floor upon which they are located. See individual standards for detailed descriptions.
Floor Plan
A scaled graphic representation of a horizontal section looking down through a building customarily taken at an elevation of three feet above the finished floor unless noted otherwise. Can be part of the working drawings, record drawings, space plan, or "core and shell" background drawings either on paper or in a CAD file.
Floor Plate
A floor of a building, as depicted by a floor plan, encompassing the major building elements on the floor like the exterior enclosing walls, columns, core walls, elevators, stairs, and the like. Usually refers only to core and shell building elements without tenant or occupant fit-up.
Floor Rentable Area
A term used by the BOMA Standards to describe the result of subtracting Major Vertical Penetrations from Gross Measured Area on a floor. This is different than the Rentable Area of the floor, which includes a pro-rata portion of Building Common Area.
Floor Service Area
A term used by the Washington Standard to describe the Floor Common Areas in the BOMA Standard except for corridors on multi-tenant floors. Examples include toilets, janitor, phone and electrical closets and mechanical rooms and their enclosing walls.
Floor Usable Area
A term used by the BOMA Office Standard connoting the sum of Office, Store and Building Common Areas on a floor.
A unit of length used in the Imperial System equal to 12 inches. Since 1959 the International Foot (where the inch is defined as exactly 2.54 centimeters) is the legal foot in most states. However, the Survey Foot (set in 1893 by the relationship that one meter equals 39.37 inches), is slightly longer (by about 1 foot in 100 miles) is still the legal standard in some states.
Footprint, Building
The area enclosed by the Building Perimeter at the ground level of a building. If the building were cut horizontally at grade level and removed, this would be the area of the remaining scar upon the site.
Football Field
An athletic field for American football having official NFL measurements of 360 feet by 157 feet, or 56,520 square feet. This measure is used to visualize the approximate size of large floor areas like the Pentagon since 117 football fields is easier for some to visualize than its gross area of 6,636,360 square feet.
Strips of wood or metal attached to a wall or other surface to provide a fair and even surface for the attachment of another finished material such as wood paneling. If furring is attached to a finished surface, it encroaches into a tenant's usable area, requiring adjustment to apparent field dimensions.
Acronym for Global Positioning System, a system that employs satellites and ground-based equipment for locating points on the surface of the earth. The best surveying GPS systems have sub-centimeter accuracy that approaches the accuracy needed for building area measurements, but they are very expensive and have reception problems indoors. Inexpensive hand-held GPS units have the same reception problem and they do not have sufficient accuracy for building area measurement, although they can locate a building well enough to find it.
(1)The slope of a surface. For instance, a 2% grade indicates a change in elevation of 2 feet vertically for each 100 feet of horizontal distance.
(2)The surface of the ground at the outside face of the exterior enclosing wall. An interior floor that is within 2 feet of grade is usually deemed to be “at grade.” See also Level.
Gross Area
The total of all areas of a building. The term is commonly used but its measure is defined differently by different stakeholders, which include designers, developers, cost estimators, appraisers, property tax officials, real estate brokers, financial institutions, insurance companies, building code & zoning officials, property managers and facility managers. There is no single accepted method of measuring Gross Area.
Gross Building Area (GBA)
A term used by federal agencies to measure multi-family properties and industrial buildings, and by the 1996 BOMA Standard. It is similar to Gross Area.
Gross External Area (GEA)
A term used in the United Kingdom, defined in the RICS Standard, for the area of a building measured externally at each floor level.
Gross Floor Area (GFA)
See “Floor Area, Gross”, “Gross Area”, Zoning Floor Area”.
Gross Internal Area (GIA)
A term used in the United Kingdom, defined in the RICS Standard, for the area of a building measured to the internal face of perimeter walls at each floor level. See also Net Internal Area.
Gross Leasable Area (GLA)
Used in retail leasing. Generally the floor area available for the exclusive use of a retail tenant measured to the outside face of exterior walls and the centerline of demising walls separating tenants. It includes basements and mezzanines. In Australia, GLA stands for Gross Lettable Area and is well defined in the Property Council’s Method of Measurement standard.
Gross Living Area (GLA)
A term used by residential appraisers to describe finished, above-grade residential space, measured to the outside face of exterior enclosing walls. Also referred to as Residential Living Area in the 1995 version of the AIA D-101 Standard, the measurement method is not defined in any major published measurement standard.
Gross Measured Area
From the BOMA Office Standard, the total of all fully enclosed floor areas of a building, measured to the Dominant Portion of the Finished Surface of exterior enclosing walls, including basements and penthouses. See the BOMA Standard.
Gross Rentable Area
Another term for Rentable Area, not defined by the BOMA Standard.
Grossing Up
A Canadian term for applying an R/U Ratio to Usable Area to determine Rentable Area. It is not defined by the BOMA Standard and is not to be confused with the Grossing Up of variable operating expenses as defined by the BOMA Escalation Handbook for Office Buildings.
The Greater Washington Commercial Association of Realtors, with URL www.gwcar.org.
GWCAR Standard
The Standard Method of Measurement, A Formula for Calculating Rentable Office and Retail Space, published by the GWCAR and used only in the District of Columbia and nearby areas of Virginia and Maryland. It is sometimes referred to as the “DC Standard” or the “Washington Standard”.
A common unit of area in the metric system equal to 10,000 square meters, or about 2.471 acres in the imperial system. It is the principal unit for expressing land area in most of the world but is generally not employed to express floor areas in buildings.
Horizontal Boundary
In multi-story common interest communities, a plane of elevation relative to an established benchmark that defines either an upper or a lower boundary of a unit.
Acronym for Industry Foundation Class, a classification system for building components (including floor area classifications) being developed by the International Alliance for Interoperability (IAI) for use in CAD and BIM software.
The International Facility Manager’s Association, with URL www.ifma.org.
IFMA Standard
The Standard Classification for Building Floor Area Measurements for Facility Management, designated ASTM Standard E 1836-01 (current version).
Imperial System
The system of measurement units commonly used in the United States which includes units of length like miles, yards, feet and inches with fractions to the base 2 (1/2, 1/4, 1/8, etc.) and that infamous unit of area known as the Square Foot.. The legal system of measurement in the US and nearly everywhere else in the world is the Metric System.
Pertaining to the gainful activity of producing, distributing and changing the form of raw materials, or of assembling components and parts, packaging, warehousing, and transporting finished products.
Industrial Space
Space suitable for industrial use, characterized by ceilings higher than 12 feet and interior finishes, HVAC, lighting and power unsuitable for office, institutional or retail occupancy.
Inside Gross
A term used in the GWCAR Standard for the same purpose as Gross Measured Area in the BOMA Standard.
Inter-floor Common Area
See Limited Common Area. This is not the same as Interstitial Space.
Interior Gross Area
A term used by the IFMA Standard that expresses the full area of a floor measured to the finished surface of the inside face of the exterior wall where it meets the floor.
Interstitial Space
Load-bearing platforms between floors suitable for equipment and mechanical use but not for occupancy by personnel except for maintenance purposes. Defined in the IFMA Standard and found most frequently in laboratory and medical building types. This is not the same as mezzanine space.
Intra-muros Area
AA measure of floor area under the ISO Standard that excludes the area taken up by exterior enclosing walls, similar to Interior Gross Area.
International Organization for Standardization with URL www.iso.ch located in Geneva, Switzerland. The US is represented at the ISO by ANSI, and ANSI distributes ISO standards in the US.
ISO Standard
ISO 9836, Performance Standards in Buildings – Definition and Calculation of Area and Space Indicators, a widely used measurement standard in Europe, published by the ISO and available through ANSI.
Acronym for Laser Detection and Ranging. Very accurate technology that uses lasers to generate point clouds in space to depict visible 3-D surfaces. It is possibly the future of building area measurement but currently used only in scientific, industrial and military context because of high cost.
Acronym for "Light Amplification by Simulated Emission of Radiation". Lasers are used in some electronic distance measuring equipment like the Leica Disto and Total Stations to accurately measure distance between specific points on the measuring unit and visible surfaces up to 100 meters or more away, making it an ideal technology for building area measurement
Short for Laser Distance Meter, any of a class of laser based measuring tools such as the Leica Disto or the Hilti Hand Held Range Meter that have generally made measuring tapes obsolete for the purpose of measuring interior space in buildings.
The agreement between a landlord (Lessor) and a tenant (Lessee) detailing the terms of occupancy, rent payments and the like. Because it also defines the Premises, their rentable area, and often their measurement method, it is the most important document for a metrologist to read and understand before doing any floor area measurements.
Leasable Area
Areas available for leasing to, and the use of, a tenant. Measurement method is not defined by any published measurement standard and could be anything, including Gross Area, Rentable Area, or Usable Area. In Great Britain, Australia and many other members of the former British Commonwealth, this is referred to as Lettable Area.
Lease Audit
A review of a landlord's accounting practices, expense pass-throughs and rentable area calculations under the terms of the lease by a lease auditor, an expert agent of the tenant. Lease audits can lead to rent abatement paid by the landlord to the tenant, of which the lease auditor generally keeps 30 to 50 percent as his fee.
Lease Line
Used in retail leasing (shopping malls and the like), this term describes a boundary of a demised retail premises that may or may not be associated with a wall. It can be located from a lease exhibit or a leasing plan maintained by the landlord but often cannot be determined from field observation.
Leasing Depth
The distance from a core wall of a building to the inside face of an exterior wall or the inside face of the exterior glass. If there is no central building core, it is half the distance between the exterior building walls.
See Tenant.
As used in the NAHB Residential Standard, areas of the house that are vertically within 2 feet of the same horizontal plane.
Limited Common Area
Fully enclosed space that serves more than one floor (and not accommodating occupant’s personnel, furniture or equipment) but less than the entire building. A common example is a fan room that serves the floor it is on and the floor immediately below it.
Living Area
See Gross Living Area
Load Factor
A term similar to the BOMA R/U Ratio but not defined in the BOMA Standard. A 20% load factor means that 20% of a tenant’s usable area is added to that usable area in order to calculate rentable area. Compare to Loss Factor below.
Loss Factor
A term used correctly only in conjunction with the New York Standard to mark-up usable area to rentable area, allocating common areas of the building to each floor and tenant. A 20% loss factor means that 20% of a tenant’s rentable area (R) is common area 80% and is usable area (U). To calculate rentable area from a given usable area, you must solve the equation R times 0.8 equals U, or U divided by 0.8 = R. Since 1 divided by 0.8 equals 1.25, this is equivalent to a 25% load factor, making loss factors seem lower than load factors, a fact use to advantage by some brokers.
Major Vertical Penetration (MVP)
Major openings in a floor to accommodate vertical building elements such as stairs, elevators, HVAC shafts and the like, including their enclosing walls. They are distinguished from minor vertical penetrations by various rules of thumb ranging from 64 square inches to 144 square inches (1 square foot). See BOMA Standards.
Measure Line
A term from the BOMA Industrial Standard that is similar in use to the Dominant Portion as defined by the BOMA Office Standard.
The mapping of empirical objects to numerical objects by a homomorphism (mathematician Fred S. Roberts). In building area measurement, the empirical objects are building floor areas and classes of space as determined by published measurement standards and local measurement practices. The numerical objects are floor areas used in leasing, management and valuation of real properties.
Measuring Wheel
(1) A hand-held field measuring device that utilizes a wheel linked to a meter that displays distance when rolled over a surface. Generally used for construction quantity-take-offs (carpet, paint, etc.) and approximate distances. Not an appropriate measuring tool for accurate building area measurement.
(2) A hand-held desk-top measuring devise utilizing a small wheel linked to a digital display showing the distance that the wheel is rolled over a floor plan, often to the scale of the plan when correctly configured. Used for approximate distances and construction quantity take-offs for cost estimating. Not an appropriate tool for accurate building area measurement.
A measure of length used in the Metric System equal to the length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 second. A centimeter is 1/100th of a meter. An International Foot equals exactly 0.3048 meters. A square meter is approximately equal to 10.76 square feet.
Metric System
The International System of Units, also known by the French abbreviation SI (Systeme International d'Unites), used for measurement by the entire world with the only significant exception being the United States of America. For real estate purposes, the USA uses the Imperial System.
One who professionally engages in metrology.
The scientific study of measurement and the application of measurement standards.
A floor structure within the exterior walls of a building and between two floors, capable of supporting personnel, equipment, storage or manufacturing. The area of a mezzanine is limited by some codes in some occupancies to some fraction (like 1/3) of the area of the floor immediately below. See the BOMA Industrial Standard.
Mixed-use Development
A property that accommodates different uses. Living over a store was an early form combining retail and residential uses. Discourage by many zoning codes, it has become a popular tool for urban revitalization that presents measurement challenges because of a lack of published measurement standards.
Multi-tenant Floor
A floor on which the Usable Area is or can be leased to more than one tenant. On a floor with two tenants, its Usable Area gets subdivided three ways - two tenant suites and a common corridor that then becomes Floor Common Area.
The National Association of Home Builders, , publisher of the NAHB Residential Standard through their wholly-owned subsidiary, the NAHB Research Center, with URL www.nahbrc.org.
NAHB Residential Standard
The American National Standard for Single-Family Residential Buildings / Square Footage – Method of Calculating, published by the NAHB Research Center and carrying the designation ANSI Z765-2003 (current version).
Abbreviation for Net Assignable Square Footage. See Net Assignable Area.
Acronym for National CAD Standard, with URL at www.NationalCadStandard.org that governs naming and content of "layers" used in application of CAD to buildings, including building area measurements. The AIA CAD Layer Guidelines are part of the NCS.
Net Area
A term previously used by the General services Administration Public Building Service but replaced by the term BIM Area.
Net Assignable Area
This term is used in educational facilities programming and planning to describe functional areas such as classrooms and laboratories without required building support spaces like circulation, mechanical and structural areas. See also Assignable Area.
Net Floor Area
A term used in the ISO standard to express the Interior Gross Area less the areas of all interior walls.
Net Internal Area (NIA)
A term used in the United Kingdom, defined in the RICS Standard, for the usable area of a building measured to the internal face of the perimeter walls at each floor level. It is used in much the same way as “Rentable Area” in North America although its calculation is quite different.
Net Leasable Area
Another word for Rentable Area. This term is not defined in the BOMA Standards or any major published measurement standard. This term should not be used if the BOMA Standards are being employed.
Net Rentable Area
Another word for Rentable Area. Some people also use this term to refer to Usable Area. This term is not defined in the BOMA Standards or any major published measurement standard. This term should not be used if the BOMA Standards are being employed.
Net to Gross Ratio
A term used in facilities programming and planning as a measure of building efficiency, it is a number less than one, the numerator of which is the Net Assignable Area and the denominator of which is the Gross Area.
Net Usable Area
A term used in the REBNY Standard to describe the usable area available to a tenant on a multi-tenant floor, excluding corridors but including the thickness of exterior building walls.
New York Standard
See REBNY Standard. This applies to New York City, not the State of New York.
The National Institute of Standards and Technology (successor to the National Bureau of Standards) with URL at www.NIST.gov that oversees U. S. measurement science, standards, and technology. If you suspect someone of using a rubber measuring tape you can have it calibrated at an NIST-certified laboratory, but don’t expect any government agency to certify square footage numbers. All floor area measurement standards for U. S. commercial property are voluntary.
A simple transaction or task requiring little imagination or intelligence, the opposite of doing floor area measurements.
Freedom from bias, a desired trait for those applying published measurement standards to determine floor areas that underlie transactions. Measurement disputes often arise when bias affects the parties’ application of a measurement standard. Objectivity from a qualified neutral third party can be an important factor in resolving such disputes.
Occupyable Area
A term used by some government agencies as a measure of usable area and often as the basis upon which they will pay rent. Can exclude areas included in BOMA Usable Area such as window sills, wall-mounted HVAC units and the like. Lease language determines how it is measured.
Office Area
Enclosed space usable for personnel, furniture, equipment and office support areas, which has suitable finishes, lighting, environmental controls, power, communications support and ceiling heights.
Acronym for Open Standards Consortium for Real Estate, an international group that promotes standards relating to real estate, including floor area classifications and terminology for building area measurement.
A method of roughly measuring distances by walking, counting steps and multiplying the number of steps by the average distance per step. Distances determined thereby can them by multiplied to determine floor area. This is not an accurate enough way of determining floor area for leasing or valuation purposes, but it is a useful way of quickly understanding approximate floor areas.
Partial Floor Factor
Another term for the BOMA R/U Ratio that is not defined in the BOMA Standards.
PBS Business Assignment Guide
A system for classifying, measuring and tracking space based upon a modified version of the 1996 BOMA Standard. It is employed by the US General Services Administration Public Building Service in conjunction with its STAR system to manage the square footage that it owns and leases.
Perimetric Boundary
In common interest communities, a vertical or horizontal boundary at the perimeter of a unit.
A desktop device for measuring the area of a planar region. Invented in 1894 by British mathematician O. Henrici, it was made obsolete by the use of the polyline region in CAD but can still be useful for approximate measurements of irregular areas delineated on paper.
A 2D element employed in an AutoCad drawing that is capable of determining with extreme Precision the area of the space it delineates, and also documenting the boundaries of that area. This is an AutoCad term. Other CAD systems use other terms, like shape or polygon.
The number of digits that are used to express a value. Not to be confused with Accuracy. CAD commonly expresses areas bounded by polylines with precision of 16 significant digits. That level of precision is meaningless when the precision of construction is 1/8" or less. Because of this, the normal precision used in building area measurement is 1/8" or 0.01 feet or 3mm.
The legal word, included in most leases, for the Tenant Area enclosed by Demising Walls. The best description of a premises is a graphic lease exhibit showing the floor plan with the boundaries of the Premises and its area in whatever terms are used by the lease.
Primary Circulation
Term used in the IFMA standard to describe corridors on multi-tenant floors or their functional equivalent for full-floor occupants.
Pro Forma
A financial projection of income and expenses used as a basis for securing financing for a property. An important basis for a pro forma is the rentable area of the property under the measurement standard cited in the lease in addition to the projected rent rates and other factors.
Pro-rata Share
A fraction, the numerator of which is the Rentable Area of a tenant and the denominator of which is the Rentable Area of the building. It is used in allocating certain expenses to tenants under certain types of leases.
The unit of plane angle adopted under the Metric System as an alternative to the degree. It is equal to the angle at the center of a circle subtended by an arc equal in length to the radius, approximately 57.2958 degrees. There are 2Pi radians in a circle.
Record Drawings
A graphic depiction of a building on paper or CAD that incorporates changes to the working drawings made during the construction phase of a project. These are different from as-built drawings in that they do not document all actual construction, but are still a better basis for calculating floor areas than working drawings.
The Real Estate Board of New York, with URL www.rebny.com.
REBNY Standard
The Recommended Method of Floor Measurement for Office Buildings published by the REBNY. Board member Realtors quoting square footages must use this standard, and it is used only in New York City and nearby areas of New York, Connecticut and New Jersey.
Rent Abatement (RSF)
(1) Free rent used as an incentive for prospective tenants. (from the BOMI Dictionary)
(2) A rebate of rent by the landlord to a tenant stemming from mis-measurement of Rentable Area, improper accounting practices or expense pass-throughs under the terms of a lease. Sometimes called rent restitution.
Rentable Area
Also called Rentable Square Footage (RSF), the area of a building, floor or suite used as the basis for calculating Base Rent. Different measurement standards define this in different ways. Refer to individual standards for measurement methods and definitions.
Rent Roll
A listing of each tenant and vacant suite in a building showing the rentable areas of each suite as shown on leases and that of the building as a whole, in addition to other pertinent information like lease expiration dates and the like.
Request for Information (RFI)
(1)A term used when the contractor requests clarification of construction documents after the award of contract. This is often cause by conflicts between different parts of the construction documents and sometimes results in dimensional changes to floor plans that are significant for those measuring floor areas.
(2)A request for information from prospective bidders, not including an actual proposal or bid.
Buildings or portions thereof used for human habitation, including single and multi-family houses, row houses, rental apartments, residential condominiums and rooming houses, but not hotels or motels. Only single family units and row houses have a published measurement standard. See NAHB Residential Standard.
R/U Ratio
A figure greater than one, the numerator of which is Rentable Area and the denominator of which is Usable Area, which allocates Common Areas to Usable Areas and Basic Rentable Areas. There are Floor R/U Ratios, Building R/U Ratios and occasionally Campus R/U Ratios. Refer to specific standards for detailed definitions. This is often incorrectly called an R/U Factor, and is sometimes referred to as an Add-on Factor, Common Area Factor, Loss Factor, Load Factor, Gross-up Factor or Partial Floor Factor.
Retail Area
A term used in the GWCAR Standard to define Store Area, but optionally including certain exterior areas such as outside dining for restaurants or carry-out food establishments, or a portion of the main building lobby.
The Royal Institute of Chartered Surveyors with URL www.rics.org, a London-based standards and membership organizations for professionals involved in land, valuation, real estate, construction and environmental issues. They publish the RICS Standard.
RICS Standard
The Code of Measuring Practice, a Guide for Surveyors and Valuers, published by the Royal Institute of Chartered Surveyors (RICS), used in the United Kingdom.
To change the value of recorded digits to some other value considered more desirable for the purpose at hand by dropping or changing certain digits. If your CAD software reports that a polylined area contains 45.1234 units, you would round that value to 45.12 because the last two digits are a misleading expression of accuracy for floor area measurement. Incorrect rounding can lead to errors in floor area measurement. Use the “round-to-even” rule and refer to NIST Handbook 44, Appendix A, Section 10 for standards and practices of rounding.
Rounding Error
This occurs when the sum of a string of correctly rounded numbers is different than the sum of those same numbers un-rounded. This kind of rounding error can be unavoidable in a short string if numbers but tends to be minimized in a long string of numbers. To help avoid rounding error, always use one or two more digits in your calculations than you require in your final result.
Round-to-Even Rule
When the last digit of a number is a 5, the digit to its immediate left is increased by one if it is odd. Otherwise, it is left even. This helps eliminate an upward bias caused by always rounding up when the last digit of a number is 5.
(1) A graduated instrument that allows a measurer to determine linear distances from paper floor plans that are drawn to scale for the purposed of calculating floor areas. Sometimes incorrectly referred to as a "ruler"
(2) The ratio between a drawing of a floor and the size of the actual floor it represents. Most commercial buildings are drawn at a scale of 1/8” = 1’-0”, called “eighth scale”. Small buildings and houses are most often drawn at “quarter scale”
Secondary Circulation
Used by the IFMA Standard, corridors and walk-ways required within the Usable Area of a tenant or department, required for access and egress to/from all Assignable Areas.
Shadow Space
See Vacancy
Shop Drawings
Detailed, accurate drawings produces by individual trades from which a building is actually constructed. The most reliable source of dimensional information short of field dimensions.
Square footage that disappears between the pro forma and the rent roll due to lease negotiations, the dynamics of leasing or inadequacies in the method of accounting for square footage.
Abbreviation for the French term Systeme International d'Unites, the Metric System.
Single Tenant Floor
A floor on which all usable area is completely occupied or leased by a single tenant.
The Society of Office and Industrial Realtors with URL www.sior.com, a organization that collaborated with BOMA in development of the BOMA Industrial Measurement Standard.
Swedish Standards Institute with URL www.sis.se that publishes a measurement standard used in Sweden, Area and volume of buildings - Terminology and Measurement, SS 021053.
Space Management System
A system that determines and tracks space occupancy, density and utilization by department and division within an organization for the purpose of optimizing space utilization and minimizing occupancy costs. Square footage figures from these systems drive chargeback systems.
Space Planning
The process of translating a space program into a physical layout or floor plan that satisfies an occupants needs in terms of square footage, adjacencies, circulation, workflow, capacity for growth and many other criteria.
Space Program
A document specifying the comprehensive facilities requirements of a user of space. A significant part of a program is the Space Requirements Projection. Also called a Facilities Program.
Space Requirements Projection
A projection of the Usable Area needed by an occupant at one or more future time horizons. It is often based upon space standards, a detailed space inventory and circulation factors. When done for tenants, they usually assume that basic building services (toilets, fan rooms, and the like) are part of the base building and are therefore excluded from the program.
Space Standards
A documented standard allocation of square footage to each position or function within an organization. It is used as a basis for doing a space requirements projection as well as a tool to control actual allocation of space in many organizations.
Spatial Program Validation
A process used by the US General Services Administration Public Building Service to evaluate proposed building designs for conformance with programmed space requirements. This utilizes explicit measurement standards and documentation requirements outlined in the PBS Business Assignment Guide and the GSA BIM Guide.
A written part of the Construction Documents that sets out requirements for materials, equipment, construction systems, standards and workmanship as well as standards for construction services required to produce the work. Occasionally there will be information in the "specs" of interest to a person measuring floor areas of un-built buildings.
Space Identifier, a term used in the PBS Business Assignment Guide representing a human-assigned number that uniquely identifies every space on all floors of a building. Not to be confused with a GUID, or Global Unique Identifier, that is used internally by a CAD or BIM system to track building elements like floor areas.
Square Foot (SF)
A square unit of area measuring twelve inches on each of its four sides that becomes grotesquely distorted when found in office buildings (attributed to John Windsor, past chair of the BOMA Method of Measuring Floor Area Committee).
Square Footage
A term used in the BOMA Standard and others in the real estate industry in parts of the world under the Imperial System to describe a quantity of floor area.
Stacking Chart
A horizontal bar chart that used a "stacked bar" for each floor of a building to indicate the square footage occupied by each tenant, department or vacant suite on each floor. Easily implemented in Excel spreadsheet software and very useful for developing strategy for phased re-stacking of organizations occupying multiple floors or buildings.
Software distributed by BOMA that automates some aspects of floor area calculations under the BOMA Office Standard.
An acronym for System for Tracking and Accounting for Real Property, used by the US General Services Administration to manage the space that it owns and leases. Square footages in the STAR system are based upon a modified 1996 BOMA standard described in the PBS Business Assignment Guide.
Storage Area
Space suitable only for the storage of materials and equipment and not for occupancy by personnel, by virtue of inadequate lighting, finishes, environmental controls, power, access, egress, or ceiling height.
Store Area
Space on the street level of an office building that is suitable for retail occupancy. This is not the same as retail space in shopping centers and is defined in the BOMA and New York Standards.
Strategic Facilities Planning (SFP)
The process of crafting a facilities plan for an organization that integrates with and supports its business plan while minimizing occupancy costs. A good space management system is a foundation for an SFP.
Structural Density
A term used in real estate development, meaning the ratio of the total ground floor area of a building to the total area of its site. Building area for this purpose is measured to the outside face of exterior enclosing walls. Average urban structural densities in the U. S. have been declining since 1945, which is a measure of increased urban sprawl.
Support Space
In a space requirements projection, space for functions other than workstations occupied by staff. Includes conference rooms, filing areas, reception spaces and the like but does not include primary or secondary circulation space.
As a noun, a document that locates the boundaries of a site or parcel of land relative to a public benchmark or plat, and that may show the location and size of the footprint of improvements thereon. For a metrologist, a survey can be not only useful but also critical in the case of buildings that are intersected by property lines or easements.
A term used in architectural programming meaning difference between the Gross Area (or the Usable or Rentable Area) of a building or portion thereof and the Assignable Area required by a tenant/occupant. Its use is described in Programming for Design, a book authored by Edith Cherry, FAIA.
An occupant (Lessee) of space who does not own it but who has tendered legal consideration to the owner (Lessor) in return for certain rights for the use and “quiet enjoyment” of a defined demised floor area.
Tenant Area
Space that is used exclusively by a tenant for their personnel, furniture, equipment, storage, support, and processes of any sort. It includes Secondary Circulations and, for a tenant occupying a full floor, Primary Circulation as well. It may be applied to any type of occupancy (office, industrial retail, etc.) and so can be measured many different ways.
Tertiary Circulation
Space allowing flow of people through assignable spaces. For example a file room may include an aisle that not only allows for opening of file drawers but also passage of staff through the file room to other assignable spaces.
The allowable difference between an area calculation made by an individual and the actual area of a subject space, floor or building. If the Tolerance is 1%, then two individual’s area calculations must always be within 2% of each other (one could be 1% high and the other 1% low).
Total Station
A sophisticated (and costly) surveying instrument that combines the functions of a transit, a level and EDM with a computer to enable very accurate measurements of points on land and in buildings. For distances of over 100 meters, a Total Station is superior for building area measurements than a hand-held DME. However, a hand-held DME used professionally is more mobile, faster and sufficiently accurate for most building measurements.
Transferable Development Rights (TDR)
A mechanism allowed by some jurisdictions for increasing the FAR on one site by purchasing rights to build floor area within the FAR of another site. See definitions for Floor Area Ratio and Zoning Floor Area.
A subset of geometry that deals with triangles and the relationships between their dimensions and angles. Abbreviated "trig", it employs trigonometric functions like Sine, Cosine and Tangent. Trig, including the Law of Cosines, and is useful in measuring irregular floor plans.
Unit Area
A physical portion of a Common Interest Community designated for separate ownership or occupancy, the boundaries of which are described by a Common Interest Ownership Act.
Usable Area
Fully enclosed space that is available for the exclusive use of a building occupant for occupant’s personnel, materials, furniture, fixtures, and equipment. Different standards measure this in different ways. It is referred to in leases as The Premises.
There are two types of vacancies: (1) floor areas that are not producing rental revenue under lease to a tenant and (2) floor areas that are producing rental revenue under a lease but are not occupied by the tenant. The former is considered true vacant space whereas the latter is called Shadow Space because of the likelihood that it will become true vacant space when the lease term expires.
Vacancy Rate
The amount of rentable area that is truly vacant (not including shadow space) divided by the total rentable area in building or group of buildings.
The difference between two area calculations of a subject suite, floor or building area made by two individuals. The area calculation of a building owner is deemed accurate if the variance between their area calculation and that of another party is less than 2% under the BOMA, GWCAR and NAHB Standards.
Vault Space
A term used to describe space, generally in an urban context, that is an extension of a basement beyond the Building Line, often under public rights of way such as sidewalks and plazas. This has nothing to do with bank vaults but derives its name from the masonry vaulting once used to support the sidewalk, street or alley above.
Vertical Boundary
In common interest communities, any boundary of a unit that is not a horizontal boundary.
Vertical Penetration
see Major Vertical Penetration.
Void Area
A term used in the IFMA Standard to describe portion of an enclosed floor area that is open to the floor below. It is sometimes indicated on plans with the abbreviation "OTB" for Open to Below. Examples are an upper level of a multi-story atrium or a portion of a ramp (sloping floor) whose area is included in the floor area of a lower level. It is distinguished from Major Vertical Penetrations in that it does not usually provide inter-floor building services like elevators, stairs and mechanical shafts.
Washington Standard
See GWCAR Standard. This refers to Washington DC, not the State of Washington.
Working Drawings
Graphic depictions of a building on paper or CAD, prepared as the basis for a construction contract. They include floor plans at multiple scales, building and wall sections, details and schedules, as well as architectural, structural, mechanical and electrical drawings. They do not reflect changes made during construction unless stamped "As-built" or "Record Drawings". Sometimes referred to as Construction Drawings or CDs. See also Construction Documents, also referred to as CDs.
The square footage dedicated to supporting the tasks of a single worker, measured to the centerline of any normal enclosing walls or panels. In some instance, workstations are designed to be shared between two or more workers.
Zoning Floor Area (ZFA)
Floor area as measured for purposes of compliance to a zoning code. It is usually defined as Gross Area measured to the outside face of enclosing walls but is also defined by some municipal codes (Santa Monica, CA, for instance) as measured to the inside face of exterior walls and excluding certain spaces like elevator shafts, open balconies, atriums and certain other areas.

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This page revised 25-Jan-09