Understanding construction drawing set organization is essential to understanding a set of construction drawings and locating pertinent information within it. There are numerous methods used (architects tend to take this very seriously) but, at the end of the day, the Cover Sheet is the only authoritative source to understand a set’s organization. The Cover Sheet should include a drawing index that outlines the sheets in the set (see Part 1 for an overview of the Cover Sheet and title block).
A good place to start the conversation is with the organizational structure of The United States National CAD Standard(NCS). The NCS standard includes a module on Drawing Set Organization that outlines a sheet numbering system often used for commercial projects. The numbering system is also applicable to residential projects but can be less than intuitive for homeowners and may feel too complicated for smaller projects (though it appears much more complicated than it actually is).1 Whatever system is utilized, drawings are typically ordered from most general to most detailed, providing an overview of the project before getting into the specifics.2 We’ll discuss the details of the NCS numbering system in a moment, but first, let’s look at the NCS categories of drawings and their order (NCS calls these “sheet type designators”) as this will provide a good overview of what a typical set of construction drawings will contain even if it doesn’t utilize the NCS numbering system. Following is a table of the main NCS sheet type designators.
| Sheet Type | Description |
| 000 series | General (cover sheet, general notes, sometimes Specifications, etc.) |
| 100 series | Plans |
| 200 series | Exterior Elevations |
| 300 series | Sections |
| 400 series | Large-Scale Views |
| 500 series | Details |
| 600 series | Schedules + Diagrams (and sometimes Specifications) |
| 700 series | User Defined |
| 800 series | User Defined |
| 900 series | 3D Representations |
000 Series – General. The first category of drawings consists of general content such as the Cover Sheet (see Part 1) and general notes. This category can also contain life safety plans, fire-rating information such as UL assemblies, wall type details, and architectural site plans. If specifications are included in the drawing set instead of a separate project manual, they will sometimes be placed in this category as well so they don’t get overlooked at the back of the set (see 600 Series for more information on specifications).3
100 Series – Plans. Plans are probably the most recognizable of architectural drawings, the drawing set being referred to as “the plans” by many. Architectural floor plans (typically drawn at 1/4” = 1’-0” scale) represent each level of the building oriented from a top view, typically “cut” through the building about four feet above the floor. These provide the basic road map for constructing the building and typically include a foundation and/or basement plan and a plan for each level above grade (first floor, second floor, etc.). Plans are typically organized from the bottom to the top (e.g. foundation plan, floor plans, roof plan), as this is the order construction will take place (though design typically happens from the top to the bottom). These include horizontal dimensions, notes and tags that provide information on the various building components and lead the reader to the more detailed information found in the rest of the drawings. Other plans such as roof plans, finish floor plans, reflected ceiling plans, equipment plans, accessory plans and millwork plans can also be included in this category.
200 Series – Exterior Elevations. After the plans, the exterior elevations are generally the next drawings in the set (also typically drawn at 1/4” = 1’-0” scale). These provide an overview of the building’s massing, exterior finishes, vertical dimensions like floor-to-floor heights, roof slopes, and exterior doors and windows. These also include tags that correspond to those on the floor plans.
300 Series – Sections. Building sections and wall sections are the next tier of drawings. Like floor plans, sections show a “cut” through the building but have the same orientation as the exterior elevations. Building sections (typically 1/4” or 1/2” = 1’-0” scale) are typically cut across the entire building and provide an overview of the building’s construction assembly types (wall/roof/floor construction), the volume of spaces and how different floors relate (e.g. two-story spaces), and continuous load path (how the loads imposed on the building are transferred from the roof, walls and floors down to the foundation and, ultimately, the earth). Wall sections are more detailed (typically 3/4” = 1’-0” scale) and provide additional information on construction assemblies.
400 Series – Large-Scale Views. Large-scale views consist of drawings that show enlarged or “zoomed in” portions of other plan and elevation drawings. For example, the most common would be enlarged floor plans that are typically drawn at 2x’s the scale of standard floor plans (or 1/2” = 1’-0” scale). This allows space for much more detailed dimensions and notes and are often utilized for spaces like kitchens and bathrooms that contain significant amounts of information in a small area.
500 Series – Details. Details (somehow not to be confused with large-scale drawings) are, appropriately, the most detailed of architectural drawings. These can include plan, section or elevation view details and can be drafted from 1” = 1’-0” scale all the way up to full scale for millwork profile drawings. Details specific to a set of drawings will typically be tagged on a more general drawing like a wall section or floor plan. Typical details of conditions that occur in multiple locations, such as window or roof flashing details, may not be specifically tagged (though it can be helpful to tag these as well for clarity).
600 Series – Schedules + Diagrams. What an architect calls a “schedule,” almost everyone else would call a “table” (and has nothing to do with planning one’s day). It is simply a group of cells organized in rows and columns containing various types of information. Schedules are a very efficient way to organize complex data and typically contain information that is closely associated with a drawing or component. Some common examples include door, window, and finish schedules. Diagrams are a simplified visual representation of information and often explain how various components relate. A prime example is a plumbing riser diagram that shows components such as plumbing fixtures, supply lines, sanitary lines, vents, and traps represented by lines and symbols.
As noted above, specifications can also be included in this category. Specifications contain written information detailing the quality of work required by the design professional for products and their installation. Specifications can provide specific performance requirements (Performance Specifications), detailed descriptions of products and their installation (Prescriptive or “3-Part” Specifications – sometimes simplified as Outline Specifications), or require specific products (Proprietary Specifications).4 Specifications typically follow the CSI MasterFormat® organizational structure.
700 Series / 800 Series – User Defined. As implied by the name, these categories are left open to be used as needed for content that doesn’t fall into the other pre-defined categories. This can include typical detail drawings.
900 Series – 3D Representations. Lastly come 3D representations such as isometric drawings, perspective drawings (renderings), and photographs. These are often included on the Cover Sheet instead.
Sheet Numbering Systems
NCS Numbering System. The NCS standard numbering system corresponds to the above drawing categories, utilizing a two-letter/three-digit system (e.g. AD101) that provides a two-letter discipline designator (e.g. AD101), single digit sheet type designator (AD101), and two-digit sheet sequence designator (AD101). Discipline designators are fairly typical whether or not utilizing the NCS system. The second letter of the discipline designator – reserved for sub-discipline types or projects with multiple buildings – is often omitted, yielding the more common format A-101.5 One advantage to the three-digit system is utilizing the tens place digit for sub-categories within the overall series (e.g. the A-110 series can be used for finish floor plans while A-101 through A-109 are used for architectural floor plans, and so on). Below is a table of some of the most common discipline designators.
| Designator | Discipline |
| A | Architectural |
| C | Civil |
| E | Electrical |
| I | Interiors |
| L | Landscape |
| M | Mechanical |
| P | Plumbing |
| S | Structural |
Alternative Numbering Systems. Other options for sheet numbering include simply using a sequential number with the appropriate discipline designator for each sheet in the set (e.g. A-1, A-2, A-3…).6 This has the advantage of being intuitive for everyone, even those without experience reading construction drawings, and can be very effective for a smaller drawing set. From a drafting standpoint it can be more difficult to keep the set organized, as inserting a new sheet in the middle of the set will throw off the numbering for all the remaining sheets. The sheet number also doesn’t correspond to any particular category of drawings. A hybrid alternative is to utilize a decimal separator and add a sub-category similar to the NCS three-digit system (e.g. A-1.0, A-1.1, etc. might be designated as architectural floor plans and A-2.0, A-2.1, etc. might be reserved for exterior elevations, and so on).
In future entries of this journal series we will start exploring each of the main drawing categories in more detail and review the rest of the example drawing set from Part 1.
Footnotes.
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