Plan sheet numbers - Explained

Modified on Tue, 29 Oct at 1:07 PM

The sheet numbers assigned to the plans and drawings identify them with their classification, context, and purpose. Architects and Engineers use a numbering system to organize the sheets that pertain to different divisions of work, drawing types, the subject they depict, and more. Companies follow numbering system conventions that may differ from one region to another. To mitigate confusion created at various levels, it becomes evident to follow standard systems. 

There are many standards, such as the United States National CAD Standard, National BIM Standard, British CAD standards, Eurocode CAD standards, etc. By and large, these standards follow a similar pattern. However, there are some differences between them.

This article explains the numbering scheme per the US National CAD standard, with the prefixes and abbreviations used for the sheet numbering.

The sheet number comprises a sequence of alphanumeric characters with segments identifying the classification of the sheet in a hierarchical structure.

The US National CAD standard follows a three-segment structure containing the discipline designator, the sheet type, and the sequence number.

1. Discipline Designators

The first segment of the sheet number with one or two characters. These identify the construction discipline or the division of work that the sheet pertains to, for e.g., architectural, plumbing, electrical, and structural. For instance, "A" represents architectural drawings.

The discipline designator is crucial for organizing drawings by type of work. For example, sub-contractors find it helpful to have plumbing drawings grouped together, eliminating the need to sift through unrelated electrical or structural drawings.

The discipline designator can be a single-letter or a double-letter. The single-character discipline designator would suffice for projects with less number of sheets, where sheets pertaining to a single division can be further classified with the sequence numbers. 

Large and complex projects where a large number of sheets are involved require two character discipline designators. The second character serves to subdivide the discipline identified by the first character. For example, in a big shopping mall renovation, it makes sense to separate lighting and power drawings across multiple electrical sheets. But for a small home renovation, it's often easier to put them on the same or consecutive sheets. This flexibility suits the needs of various projects.

Level 1 Discipline Designator

The first letter designator typically signifies the discipline or category to which the drawing/information pertains. It serves as a quick reference to the primary focus of the content. The following table gives a list of first-letter designators with their disciplines. The list is in the order of how the sheets pertaining to the different disciplines are arranged in the plan set.

Designator

Discipline

G

General

H

Hazardous materials

V

Survey/Mapping

B

Geo-technical

C

Civil

L

Landscape

S

Structural

A

Architectural

I

Interior

Q

Equipment

F

Fire protection

P

Plumbing

D

Process

M

Mechanical

E

Electrical

W

Distributed energy

T

Telecommunication

R

Resources

X

Other Disciplines

Z

Contractor/ Shop drawings

O

Operations

Level 2 Discipline Designator

The second letter designator provides additional specificity within the broader discipline indicated by the first letter. It refines the focus of the content, allowing for more detailed categorization. For example:

  • EL denotes an Electrical Lighting plan within the electrical discipline.
  • EP denotes an Electrical Power layout plan within the same electrical discipline.

By incorporating a second letter, the system becomes more nuanced, allowing for a more granular classification of drawings and documents and facilitating efficient organization and retrieval in complex projects. Please see the table below for the standard 2-level discipline designators.

Delimiter

The discipline designator is followed by a delimiter, usually a space or a hyphen, to separate it from the next segment, namely the sheet type identifier. For example, A-101.

2. Sheet Type

The sheet type identifier plays an important role in bringing order to the diverse array of drawings within a single discipline, strategically organizing drawings from the most general to the most specialized.

Organizing Hierarchy

  • Plans (Most General) - Plans take the lead as the most general drawings. They provide a bird's-eye view, offering a comprehensive understanding of the project's overall design.
  • Elevations and Sections (More Specific): As we zoom in, elevations and sections come into play. These drawings offer a more detailed perspective, focusing on specific areas or aspects of the project.
  • Details and Schedules (Most Specific): The final act belongs to details and schedules—the most specific type of drawings. Here, every minute detail is outlined, ensuring nothing is left to chance.

To simplify, picture it as telling a story. You start with the big picture, then zoom in to highlight important scenes, and finally, you delve into the intricate details that bring the narrative to life.

The following table shows the standard numbers used for different sheet types in alignment with the US National CAD Standard:

Identifier

Sheet Type

0

General: Symbol legend, abbreviations, general notes

1

Plans

2

Elevations

3

Sections

4

Large scale drawings: Plans, Elevations, Sections (not details)

5

Details

6

Schedules and Diagrams

7

User Defined

8

User Defined

9

3D drawings, Isometric, Perspective, Photos

Delimiter

In usual practice, the sheet type identifier continues with the sheet sequence number without any delimiters in between. For example, A-101.

3. Sequence number

The sheet sequence number is a two-digit identifier assigned to each sheet in a series of drawings within the same discipline and sheet type. 

  • The numbering starts from 01, followed by 02 through 99.
  • Although many projects may only need single-digit numbers, the standardized two-digit sequence number facilitates efficient sorting.
  • The numbering can be non-sequential, with gaps in the order. This allows seamless incorporation of future additions between the existing sheets in a set. 
  • User-defined suffixes can be added to the sheet sequence numbers with delimiters, like hyphens and dots. This is useful to mark a sheet as a supplemental sheet or a partial revision. For Example, A-101-R1.

Commonly used 2-level Discipline Designators

Designator

Description of the category

G - General

GC

General Contractual

GI

General Informational        

GR        

General Resource        

 GJ        

User Defined

 GK        

User Defined

H - Hazardous materials

HA

Asbestos

HC

Chemicals

HL

Lead

HP

PCB

HR

Refrigerants

HJ

User Defined

HK

User Defined

V - Survey/Mapping

VA

Aerial

VB

Boundary

VC

Computated Points

VF

Field

VI

Digital

VL

Land

VN

Node Points

VS

Staked Points        

VU        

Combined Utilities        

VJ

User Defined

VK

User Defined

B - Geo-technical

BJ

User Defined

BK

User Defined

C - Civil

CD        

Civil Demolition

CA

Civil Alignments

CC        

Civil Profiles

CG

Civil Grading

CI        

Civil Improvements

CL

Civil Landscape Plans

CM

 Civil Details

CN        

 Civil Nodes        

CP

 Civil Paving        

CR        

Pavement Resurfacing Plans

CS

Civil Site

CT

Civil Transportation        

CU

Civil Utilities

CW

Stormwater Management Plans        

CX

Civil Typical Sections        

CJ

User Defined 

CK

User Defined

L - Landscape

LD

Landscape Demolition        

LG

Landscape Grading

LI

Landscape Irrigation

LL

Landscape Lighting        

LP

Landscape Planting 

LR

Landscape Relocation

LS

Landscape Site

LJ

User Defined

LK

User Defined

S - Structural

SB

Structural Substructure     

SD

Structural Demolition

SF

Structural Framing

SS

Structural Site

SJ

User Defined

SK

User Defined

A - Architectural

AD        

Architectural Demolition        

AE        

Architectural Elements

AF

Architectural Finishes

AG

 Architectural Graphics        

AI

Architectural Interiors        

AS

Architectural Site

AJ

User Defined

AK

User Defined

I - Interior

ID

Interior Demolition

IF

Interior Furnishings

IG        

Interior Graphics        

IN

Interior Design

IJ

User Defined

IK

User Defined

Q - Equipment

QA

Equipment Athletic

QB

Equipment Bank   

QC

Equipment Dry Cleaning

QD

Equipment Detention

QE

Equipment Education 

QF

Equipment Food service

QH

Equipment Hospital

QL

Equipment Laboratory     

QM

Equipment Maintenance

QP

Equipment Parking Lot

QR

Equipment Retail

QS

Equipment Site 

QT

Equipment Theatrical      

QV

Equipment Video / Photographic

QY

Equipment Security

QJ

User Defined

QK

User Defined

F – Fire Protection

FA

Fire Detection and Alarm 

FX

Fire Suppression

FJ

User Defined

FK

User Defined

P - Plumbing

PD

Plumbing Demolition        

PL

Plumbing Fixtures

PP

Plumbing Piping

PQ

Plumbing Equipment

PS

Plumbing Site

PJ

User Defined

PK

User Defined

D - Process

DA

Process Airs 

DC

Process Chemicals

DD

Process Demolition

DE

Process Electrical     

DG

Process Gases     

DI

Process Instrumentation

DL

Process Liquids

DM

Process HPM Gases

DO        

Process Oils        

DP        

Process Piping        

DQ        

Process Equipment        

DR        

Process Drains and Reclaims        

DS        

Process Site        

DV        

Process Vacuum        

DW        

Process Waters        

DX        

Process Exhaust        

DY        

Process Slurry        

DJ

User Defined

DK

User Defined

M - Mechanical

MD

Mechanical Demolition

MH        

Mechanical HVAC        

MI        

Mechanical Instrumentation        

MP        

Mechanical Piping        

 MS        

Mechanical Site        

MJ

User Defined

MK

User Defined

E - Electrical

ED        

Electrical Demolition        

EI        

Electrical Instrumentation        

EL        

Electrical Lighting        

EP        

Electrical Power        

ES        

Electrical Site        

ET        

Electrical Telecommunications        

EY        

Electrical Auxiliary Systems        

EJ

User Defined

EK

User Defined

W - Distributed energy

WC        

Distributed Energy Civil        

WD        

Distributed Energy Demolition        

WI        

Distributed Energy Interconnection        

WP        

Distributed Energy Power        

WS        

Distributed Energy Structural        

WT        

Distributed Energy Telecommunications        

WY        

Distributed Energy Auxiliary Systems        

WJ

User Defined

WK

User Defined

T - Telecommunication

TA        

Telecommunications Audio Visual        

TC        

Telecommunications Clock and Program        

TI        

Telecommunications Intercom        

TM        

Telecommunications Monitoring        

TN        

Telecommunications Data Networks        

TT        

Telecommunications Telephone        

TY        

Telecommunications Security        

TJ

User Defined 

TK

User Defined

R - Resources

RA        

Resource Architectural        

RC        

Resource Civil        

RE        

Resource Electrical        

RM        

Resource Mechanical        

RR        

Resource Real Estate        

RS        

Resource Structural        

RJ        

User Defined        

RK        

User Defined        

X - Other Disciplines

XS        

Street Lighting Plans        

XJ        

User Defined        

XK        

User Defined        

Z - Contractor/ Shop drawings

ZJ        

User Defined        

ZK        

User Defined        

O - Operations

OJ        

User Defined        

OK        

User Defined        

 

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