Architectural sheet numbers follow a simple pattern: a discipline letter, a sheet type digit, and a sequence number. In A-101, "A" means architectural, "1" means plans, and "01" means the first sheet in that series, so A-101 is the first architectural floor plan. This is the structure of the US National CAD Standard (NCS), and most offices that do not follow it exactly still use a close variant. The sheet number sits in the title block, usually in the bottom right corner, in the largest text on the sheet.
Discipline designators
| Letter | Discipline |
|---|---|
| G | General (cover sheet, index, code summary) |
| H | Hazardous materials |
| V | Survey / mapping |
| B | Geotechnical |
| C | Civil |
| L | Landscape |
| S | Structural |
| A | Architectural |
| I | Interiors |
| Q | Equipment |
| F | Fire protection |
| P | Plumbing |
| D | Process |
| M | Mechanical |
| E | Electrical |
| T | Telecommunications |
| R | Resource |
| X | Other disciplines |
| Z | Contractor / shop drawings |
| O | Operations |
A second letter can subdivide a discipline, for example AD for architectural demolition or AS for architectural site.
Sheet type digits
| Digit | Sheet type | Example |
|---|---|---|
| 0 | General: symbols, legends, notes | A-001 General notes and symbols |
| 1 | Plans | A-101 Ground floor plan |
| 2 | Elevations | A-201 Exterior elevations |
| 3 | Sections | A-301 Building sections |
| 4 | Large-scale views | A-401 Enlarged toilet plans |
| 5 | Details | A-501 Wall details |
| 6 | Schedules and diagrams | A-601 Door and window schedules |
| 7, 8 | User defined | Office-specific use |
| 9 | 3D representations | A-901 Perspectives, isometrics |
A typical architectural sheet list
| Sheet | Title |
|---|---|
| G-001 | Cover sheet and drawing index |
| A-001 | General notes, symbols and abbreviations |
| A-101 | Ground floor plan |
| A-102 | First floor plan |
| A-103 | Roof plan |
| A-201 | Exterior elevations |
| A-301 | Building sections |
| A-501 | Details |
| A-601 | Schedules |
Other numbering systems you will meet
- Simple sequential: A1, A2, A3. Common on small projects; quick, but adding a sheet in the middle breaks the order.
- Floor-based: A-100 for the basement, A-101 ground floor, A-102 first floor, so the last digits follow the level.
- ISO 19650 file naming (UK and Europe): a longer code such as PRJ-ORG-ZZ-01-DR-A-1001, where fields identify project, originator, volume, level, document type, role and number. The short sheet number on the drawing is the last part.
Rules that keep a set easy to use
- Pick one system at the start and keep it to the end of the project.
- Leave gaps (A-101, A-102 ... A-110) so new sheets fit without renumbering.
- Never reuse a number for a different drawing, even after a sheet is deleted.
- Use the same sheet number in the title block, the drawing index, the file name and every reference bubble.
Finding a sheet in a large PDF set
A combined PDF set can run to hundreds of pages, and the sheet number is how people navigate it. In Ncored, the PDF editor we built in our architecture studio, you can search the text of the set for "A-301" and jump to it, or move through the thumbnail sidebar, and large sets stay smooth to scroll and zoom on Windows and Mac. See viewing a multi-sheet PDF set.
Frequently asked questions
What does A-101 mean on a drawing?
Architectural discipline (A), plan sheet type (1), first sheet in that series (01): normally the first architectural floor plan.
Where is the sheet number found on a drawing?
In the title block, usually the bottom right corner of the sheet, often in the largest text so it can be read when the set is bound or filed.
What is the sheet numbering standard for architectural drawings?
In the US, the National CAD Standard's Uniform Drawing System: discipline designator, sheet type digit and sequence number. Elsewhere, offices often follow ISO 19650 naming or their own convention.
What sheet number is the cover sheet?
Often G-001 or G-000 under the NCS, or simply 000 or CS on smaller sets.
Related: architectural title block guide, what is a title block, drawing sheet sizes.