What Building Size Do I Use?

ATTOM Collects information about the size of the buildings on a property. The primary source of this information is the County Tax Assessor. Each county can have its own definitions and may only choose to collect a subset of information about its properties. This can get complicated when their are multiple buildings on a property and/or there is a mixture of what is deemed to be finished space and unfinished space.

Total Space

The total interior size of the buildings (finished or unfinished).

AdditionsSquareFeet: The total square footage of additional living space built on the the original structure
AtticSquareFeet: The total area of the attic
FirstFloorArea: The total area covered by ground floors of all buildings on the property
FloorUpperSquareFeet: The total area above the ground floor covered by ground floors of all buildings on the property
GarageSquareFeet: The total interior area of all garages on the property
Gross Area: The total area of all buildings on the property
SecondFloorArea: The total area of the second floor for all buildings on the property

Finished/Unfinished Space

This generally relates to livable areas of a building and is defined based on building specifications. Rooms that are not insulated and/or have treatments on the floors, walls, and ceilings that meet certain standards may be considered unfinished spaces. e.g. attics, basements, garages, and equipment rooms.

BuildingSquareFeet: The total square footage of all the livable (finished) area in all the structures on the property
FinishedSquareFeet1: The total finished areas on the first (ground) floor of all buildings
FinishedSquareFeet2: The total finished areas on the second floor of all buildings
FinishedSquareFeet3: The total finished areas on the third floor of all buildings
FinishedSquareFeet4: The total finished areas on the fourth floor of all buildings

Finished Attic

For an attic to be considered finished it usually must meet the following criteria:

  • Walls should be insulated, drywalled and finished (e.g. painted)
  • Directly accessible via permanent stairs
  • Floors must be covered with an installed cover (e.g. floor boards, tiles, carpet)
  • Adheres to all relevant building codes

AtticFinishedSquareFeet: Total area of the finished portion of the attic
AtticSquareFeet: Total area of the attic
AtticUnfinishedSquareFeet: Total area of the unfinished portion of the attic

Finished Basement

To qualify as a finished basement, the area must be: -

  • Contiguous with the rest of the house
  • Directly accessible via permanent stairs and/or direct access (separate door)
  • Floors must be insulated underneath and covered with an installed cover (e.g. floor boards, tiles, carpet)
  • Walls should be insulated, drywalled and finished (e.g. painted)
  • Adheres to all relevant building code

BasementFinishedSquareFeet: Total area of the finished portion of the basement
BasementSquareFeet: Total area of the basement
BasementUnfinishedSquareFeet: Total area of the unfinished portion of the basement.

It may be necessary to use Basement1Key and/or Basement2Key in conjunction with DimBasement to determine if at least part of the basement is considered finished.

Finished Garage

For a garage to be considered finished it must have:

  • Floors covered with an installed cover (e.g. floorboards, tiles, carpet)
  • Walls insulated, drywalled, and finished (e.g. painted)
  • Ceilings covered with no exposed beams or wiring
  • The garage door replaced with a window and/or wall
  • Adheres to all relevant building codes

CarportSquareFeet: The total area of all carports located on the property. Thee would be considered unfinished.

Other Rooms

ATTOM Cloud may also include information about the space assigned to specific types of rooms or building on a property: -

  • BalconyArea
  • BathHouseArea
  • BoatHouseArea
  • CabinArea
  • CourtyardArea
  • DeckArea
  • Driveway Area
  • GazeboArea
  • GraineryArea
  • GreenhouseArea
  • KennelArea
  • LeanToArea
  • LoadingPlatformArea
  • MilkHouseArea
  • OfficeArea
  • PatioSquareFeet
  • PoleStructureArea
  • PoolHouseArea
  • PoolSquareFeet
  • SheadArea
  • SiloArea
  • StableArea
  • StorageBuildingArea
  • UtilityBuildingArea
  • UtilityRoomArea

ATTOM API

Even thought the data is derived from ATTOM Cloud, ATTOM API using different names for many of the building size fields.

  • bldgsize - PropertyFeature.BuildingSquarefeet
  • grosssize - PropertyFeature.GrossArea
  • grosssizeadjusted - PropertyFeature.BuildingSquarefeet
  • groundfloorsize - PropertyFeature.FinishedSquareFeet1
  • livingsize - PropertyFeature.BuildingSquarefeet
  • sizeInd -  if property category = Residential, then 'LIVING SQFT' else 'BUILDING SQFT'
  • universalsize - PropertyFeature.BuildingSquarefeet
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