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Building, File, and Drawing Numbers


The numbering system identifies a building, the computer files for a building, and each drawing in a file.


Number structure

A computer file number has the format BRF where B is the building number, R is the revision digit, and F is the file digit. A drawing number has the format BRFD where D is the drawing digit.

Building number

The building number B has four digits, with R suffixed for a reverse building. File numbers and drawing numbers do not include R. Instead, the illustrated building and its reverse have different file digits.

  1. The first digit is 1 for a one-story building, 2 for a two story house or rowhouse building, or 4 for a two story up-and-down building.
  2. The second digit tells the number of bedrooms per unit.
  3. The third digit identifies a particular model.
  4. The fourth digit tells the number of units in the building.

Revision digit

The revision digit R starts at 0. When a building is revised, the revision digit is incremented.

File digit

The file digit F identifies a particular file for the building.

  1. (not used)
  2. floor plans and schematic plans
  3. foundation plan, roof plan, and elevations
  4. reverse floor plans and schematic plans
  5. reverse foundation plan, roof plan, and elevations
  6. (not used)
  7. (not used)
  8. (not used)
  9. (not used)
  10. (not used)

Drawing digit

Floor plans and schematic plans

In two story buildings, the second story plans are sometimes included in the first story plans instead of being separate drawings.

   LAYER                     COLOR
   0  meta                   green
   1  first story room       black
D  2  first story floor        red
D  3  first story schematic   blue
   4  second story room      black
D  5  second story floor       red
D  6  second story schematic  blue
   7  basement room          black
D  8  basement floor           red
D  9  basement schematic      blue

The meta layer has title block information, drawing legends, and guidelines. For each story, the room plan is created by combining the meta layer and the room layer.

For each story, the floor plan is created by combining the room plan and the floor layer. The drawing digit D is the floor layer number.

For each story, the schematic plan is created by combining the room plan and the schematic layer. The drawing digit D is the schematic layer number.

Foundation plan, roof plan, and elevations

   LAYER                     COLOR
   0  meta                   green
D  1  foundation             black
   2  foundation sheet 2     black
   3  (not used)             green
D  4  roof                     red
   5  (not used)             green
D  6  elevations              blue
   7  elevations sheet 2      blue
   8  elevations sheet 3      blue
   9  elevations sheet 4      blue

The meta layer has title block information and guidelines. A drawing sheet is formed by combining the meta layer with one of the other layers.

All sheets of a drawing have the same drawing number. For the foundation plan, the drawing digit D is 1. For the roof plan, the drawing digit D is 4. For elevations, the drawing digit D is 6. If a drawing has more than one sheet, each sheet is labeled "Sheet S of N" where S is the sheet number and N is the number of sheets.