National CAD Standards

Introduction

As you will repeatedly hear this semester, strong theoretical ideas can only result in exceptional built outcomes, if you effectively translate your ideas into well-executed construction documents (CDs). Effective translation requires you to hone your construction documentation craft, specifically to be clear, concise, and legible. Thus as stated earlier in the course:

Drawing craft in planting methods serves several purposes:

  • Your drawing craft communicates the professionalism you bring to a clients project;
  • Expresses the spatial qualities (e.g., scale, texture, colors, ambiance, form, and function), inter-and intra-system relationships, and the ecological assemblages of your design; and
  • Legibility and thoroughness facilitate a well-constructed project within budget, on time, and with reduced liability.

While there is an art to beautiful, concise, and legible CDs, there are also standards to assist you in creating your CDs. These standards also facilitate collaboration among multi-disciplinary teams. In almost all cases, each design office has adopted a set of CAD standards. If these offices work on governmental projects, they have most likely selected a form of the National CAD Standards. A link to the PDF can be found on the Course Canvas Site. The benefits of a National CAD standard (USNCD), as outlined by USNCD, are as follows:

Benefits for building design professionals
1) Consistent classification, organization, and representation of CAD data for all projects, regardless of the project type or client.
2) Seamless transfer of information between architects, engineers, and other design team members.
3) Reduced preparation time for translation of electronic data files between different proprietary software file formats; predictable file translation results.
4) Reduced data file formatting and set-up time as a result of the adoption of the Standard by software application vendors.
5) Greatly reduced staff training time to teach multiple “office standards.”
6) A streamlined process for checking drawings for references, omissions, etc.
7) Automated updating of data files as the Standard evolves.
8) New opportunities for expanded services and revenue beyond building design.
9) New marketing opportunity; design firms complying with the Standard can feature compliance as a benefit to prospective clients

Benefits for the general contractor and related sub-contractors
1) Consistent organization of CAD data for all projects, from all sources.
2) Consistent drawing sheet order and sheet organization; information appears in the same place in all drawing sets, regardless of the source.
3) Reduction of discrepancies, reducing the potential for errors, change orders, and construction delays.
4) Consistent detail reference system.

Benefits for the client/building owner
1) Consistent organization of data for all projects, from all sources.
2) Greater clarity of communication of design intent to the client.
3) Streamlined electronic data management of facility management data.
4) Enhanced potential for automated document storage and retrieval.
5) Streamlined construction document checking process.

Benefits for the entire building design and construction industry
1) Reduced costs for training resulting from the common language of data classification and organization for CAD.
2) Improved preparation and training of prospective employees at undergraduate and graduate institutions of higher learning.
3) Enhanced potential for automated training and distance learning.
4) Elimination or reduction of a major barrier to the free exchange of building construction data, creating an opportunity to improve quality, improve efficiency and reduce costs in the building design, construction, and maintenance process.
USNCD, 2014

To better assist you in creating CDs, we will specifically cover drawing or sheet naming conditions and numbering, layer naming, drawing standards, and plotting guidelines. If you want further information on graphic scales, north arrows, how to layout drawings sheets, text sizing, etc. which can be found in the USNCD PDF file on the course Canvas site. Tables and imagery below are from the NCSD, 2014 document and are for educational purposes only.

Sheet Naming and Numbering Conventions

When following the USNCD, all drawing sheets should be named and numbered per Table 1. However, note we will not use all of these plans this semester, as we are only focused on planting methods, we will specifically focus on the L-103 and possibly L-104 Sheets. Also, note there are two levels of sheet naming complexity, depending on your project’s needs.

Table 1: USNCD sheet numbering and naming conventions.

CAD Layer Conventions

It is critical that you manage your layers correctly, as this is how CAD ensures that your documents print with the correct line weight and line type. Hence, you must make sure the item you are drawing is always on the correct layer, and if you, want it to have a different line weight, color, or line type, it must be on its own unique layer.  Without detailed layer management, your drawings will be messy and not legible. The USNCD layer list is based on the AIA CAD Layer guidelines. If you require more detail regarding CAD layering, please see the USNCD PDF linked in the course Canvas site and read the section (bookmark) titled “AIA CAD Layer Guidelines.”

In this section, we will specifically focus on the Landscape Layer List, which consists of Major and Minor Group field codes related to landscape architecture (Table 2).

Major Field Codes

Table 2: Major and minor layer field codes

Minor Field Codes

drawing standards

Drawing orientation and north arrow

Your plans may be oriented on a sheet in a variety of ways to display the requirements of the project and the intent of the designer. Ideally, the entire plan should be shown on one sheet. However, for a variety of reasons, this is not always possible. If it cannot fit on one sheet, the plan should be subdivided into convenient segments with
match lines provided to reference where the floor plan is continued. However, in this class, all plans should be contained on one sheet, see the assignment statements for further detail. Civil and landscape plans may orient the drawing in a manner that will allow the site plan to fit within the sheet boundary when drawn at the most appropriate scale. It is preferable to orient the site plan in the same manner as the floor plans whenever possible.

A sheet containing small scale plans for all levels drawn at 1:200 or 1:500 (1/16″ or 1/32″ = 1′-0″) scale or smaller may be included in the set to provide an overview
of the project and serve as a quick reference. This sheet is useful if the plan is divided into segments to fit in a standard size sheet. It is also useful if the project will be constructed in phases. The consistency of the display of information throughout the set is important. For example, a plan detail should be shown in the same orientation as it is shown on the plan. An enlarged section detail should also have the same orientation as the section or plan from which it is derived.

drawing layout

A uniform order to organize the drawings is important, as it makes the project easier to execute. Additionally, it prevents conflicts among the different types of information included in each drawing or profession.

As illustrated in the image below, CD sheets are divided into three main areas: drawing area, title block area, and production data area. The drawing area and title block area are required, while the production data area is optional. Each of these areas contains information concerning construction or reference information, project management or presentation information, and project production information.

  • Drawing Area: That portion of the sheet containing drawings, keynotes, key plans, schedules, and other graphic and text data necessary to illustrate the work.
  • Title Block Area: That portion of the sheet containing project, client, designer, sheet identification, and sheet management information needed by the user of the sheet.
  • Production Data Area: That portion of the sheet containing information on the production of the sheet.

Each of these areas contains different types of information necessary for the presentation and management of the project. These areas should be defined by a border, tick marks, or other means that graphically separate them from each other.

The practical minimum sheet margins are as follows:

  • Top and bottom margin: 20 mm (3/4 inch)
  • Left margin: 40 mm (1-1/2 inch)
  • Right margin: 20 mm (3/4 inch)

The title block is an area or portion of the sheet containing project, client, designer, and sheet identification and management. The guidelines for the title block area provide criteria for the location of like information shown in data blocks within the title block area for easy and consistent retrieval and filing of drawings. Data blocks include the following: 1) Designer Identification Block, 2) Project Identification Block, 3) Issue Block, 4) Management Block, 5) Sheet Title Block, and 6) Sheet Identification Block.

  • The designer identification block is that portion of the title block area identifying the designer or preparer of the sheet. This block may include information about the preparer including name, address, telephone and fax numbers, and email address, or other means of electronic communication. This block may also include the preparer’s logo, professional seal(s), certifications, and the names and addresses of consultants. In the case of a design-build project, it may include the entire project team. The requirements for professional seals vary from jurisdiction to jurisdiction.
  • The project identification block is that portion of the title block area that identifies the project. This block may contain information on project name and address, building or facility name, construction phase sequence, and project logo. The address, telephone, and fax numbers, and logo of the owner/client may also be included in the
    project identification block.
  • The issue block is the portion of the title block area that shows the chronological issue of, and revisions to, the sheet. The issue block has three columns identified as
    mark, date, and description. The data fields in this block may include phase issue dates, addendum issue dates, clarification dates, and revision issue dates. The number of data field lines is user-dependent. The initial entry should be placed at the bottom of the issue block, with subsequent entries placed above each previous entry, allowing for
    expansion into the project identification block if necessary.
  • The management block is the portion of the title block area that contains the management information generally used for project filing, record-keeping, or other project management information. Data fields in this block may include drawing preparer’s project number, owner’s contract number, owner’s project number, file number, design/construction phase number, CAD drawing file number, drawn by, checked by, and copyright.
  • The sheet title block is the portion of the title block area that indicates the type of information presented on the sheet. The sheet may contain one or more types of
    drawings. The title block may only include the major type of information shown on the sheet or may indicate multiple types of information (e.g., floor plan, schedules, and details).
  • The sheet identification block is the portion of the title block area that contains the sheet identifier. The system for determining the sheet identification and its format is contained in the Sheet Naming and Numbering Conventions, above. Optional data as part of the sheet identification block includes a number indicating the sheet count and total number of sheets within the set. The sheet count can be for all sheets in the drawing set, or for the count within each discipline.

scale

The scale of a drawing is the ratio of measuring units expressing a proportional relationship between a drawing and the full-size item it represents. In CAD, drawings are created at full scale, often in what AutoCAD refers to as model space and plotted at a selected scale, often through paper space and viewport settings. The selection of the proper scale determines the readability of the drawing. The scale chosen should be large enough to allow the drawing to display its graphic, dimensional, and textual content clearly, without congestion or ambiguity.

Scale can be expressed numerically and graphically. All drawings or views should indicate the numeric scale at which that view is presented. All drawings that may be reduced or enlarged should include numeric and graphic scales. Reduced drawing sets can render the numeric scale inaccurate. The organizer of the drawings should use a graphic expression of scale for clarity.

All drawings or views should indicate the numeric scale at which that view is presented. Numeric scale can be expressed in metric, architectural, or engineering as is appropriate to the project. The table below lists some commonly used scales and their purpose.

Table 3: Common scales and typical purposes.

In addition to object lines, the following lines apply to all disciplines and drawing organization:

  • Leaders are lines that connect notes, dimensions, or symbols to a point or item in a drawing. Leaders terminate with an arrowhead in proximity to the item being described
    by the notation. Leaders should be drawn in a consistent fashion, either straight or curved throughout the set of drawings. To improve readability, they should be angled so
    that they may not be confused with lines in the drawing. They should not be allowed to cross-dimension lines or each other. Leaders should start at the upper right side or upper left side of the notation.
  • Break Lines are used to indicating the cut between two parts or levels. Examples include a drawing foreshortened to fit into a detailed block or an inclined plane such as a stair or parking ramp connected between two floors. Never foreshorten parts of the drawing that require detailing.
  • Centerlines are used to indicate the center of a column, beam, wall, or opening. A thin line interrupted at intervals by a dot represents centerlines.
  • Dimension Lines are represented by a thin line connecting between extension lines defining the beginning and end of the object being dimensioned. A terminator mark
    identifies the intersection between an extension line and a dimension line. Terminator marks should be angled consistently in the same direction.
  • Limit of Construction Lines defines the area of work beyond which the contractor is not allowed to execute any work.
  • Match Lines delineate division between two or more areas of a continuous structure that must be shown on separate sheets because of sheet size limitations. Do not locate match lines on column lines, gridlines, or expansion joints. Locate them instead of at the centerline of a wall or corridor. Match lines should be shown at the same location on both sheets containing adjacent segments of the plan at the same location. A portion of plan overlap should be shown beyond the match line to establish the relationship between adjacent plan segments. This overlapped portion may be lightly shaded to avoid duplication during the cost estimating. Match lines should extend beyond the area to be matched. They may jog to avoid important elements of the plan. All match lines should be shown on the Key plan.
  • Hidden Lines represent items obscured from view by another material. Examples include steel lintels, relieving angles in elevations, and items above or below a floor
    plan. Thin dashed lines represent hidden lines.
  • Property Lines are represented by a line interrupted by double dots. They indicate the boundary of the site.

dimensions

The purpose of dimensioning is to locate each element of the project for construction. Each wall, site element, plant, hardscape, or part of detail must be tied to a fixed point such as an existing building edge or survey control point. This applies to plans and the enlargements associated with them. For sections and their details, the horizontal reference should also be called out. Dimensions must be accurate and adequate. Inadequate dimensions require clarifications during construction and possible loss of time.

Care must be taken to show a single dimension only once in its proper location. Avoid the tendency to over-dimension. It is a fine balance that will take time and practice to perfect.

  • Location: Generally, dimensions should be located outside the floor plan or other view being dimensioned. This minimizes clutter and overlap with other graphics. Dimensions outside the view should be located at the top and/or the right side of the plans whenever possible. Offset dimension lines from object lines a minimum of 14.5 mm (9/16″) and offset dimension lines from each other 10 mm (3/8″). When dimensions must be shown on the interior of a floor plan or other view, the dimensions should be arranged in continuous strings for clarity and consistency.
  • Types of Terminators: Terminators define the junction between a dimension line and the extension lines leading to the start and finish of the dimension. These terminators are in the form of either a short, slanted line (slash) or a filled arrowhead. Slashes should always be parallel. Dimension terminator selection should be consistent across the entire set of drawings. Note we require you to use slashes in this class.
  • Numeral Size and Location: Numeral size should match the size of the text in the drawing. Where possible, the numeral should be placed at the midpoint and on top of the dimension line.

Arrange dimensions from general to specific. Guidelines for dimensions are as follows:

  • Dimension fractions should not be less than 1.5 mm (1/16″) because accuracy in the field is usually not required to be more precise than that. In cases where an opening width is divided into two equal parts and the original width is 1.58 m (5′-2-1/16″), write the total width on one string and create another string stating EQ (equal) on both sides rather than label each side as 790 mm (2′-7-1/32″).
  • Check for superimposed information caused by layering.
  • Where the length of dimension lines is too short to accommodate the dimension number, show the number to the side.
  • If the drawing is not to scale, note NTS in the drawing title.

plotting guidelines

The purpose of the USNCD Plotting Guidelines are to allow consistent black-and-white and color plotting from various configurations within CAD programs. These guidelines allow consistent color plotting between any CAD program. In today’s workplace, the prevalence of plot inconsistency is compounded by multiple types of plotting hardware, printers, differing defaults in the various CAD software packages being utilized, and multiple independent development paths among users.

The tables in this USNCD version of Plotting Guidelines have removed the dependency of color for plotted line weights. This section addresses plots that can be printed using a black and white plotter, since construction documents are always printed in black and white. Considering various screen colors can be assigned to color numbers, only color numbers will be addressed. The following table assumes the CAD software utilizes color numbers and allows the user to select from 255 colors.

Table 5: Color value plotting