The American Institute of Architects, AIA, sets standards for computer-aided design — or CAD — documents. Most building projects require drawings that meet AIA standards. AIA layering standards assign specific layer names, content descriptions, colors, line types, and line weights, which make it easier to read and reference architectural drawings.

The American Institute of Architects provides over 300 label names for the sections, details, legends, and text, and other layers found in CAD drawings. Label names are made up of an initial and an abbreviation of the layers function or content.

AIA Label Names

Initials

Architectural drawings begin with the letter A, civil drawings with the letter C, electrical drawings with the letter E, etc. Typically, abbreviations are self-explanatory. For example, the layer containing the doors in a CAD document is labeled “A-DOOR Doors. It would be on the 2-yellow layer with a number 7 pen’s continuous line weight.

Colors

Each layer of a CAD file must be colored according to AIA specifications. For example, all layers pertaining to architectural annotations and dimensions are colored cyan, while layers pertaining to electrical safety are colored red. The preceding illustration of doors is on the yellow layer.

Line Weight

AIA standards also prescribe the line weight of a layer. In general, boundary lines, legends, dimensions, and notations are written with a number 4 pen, whereas construction lines, walls, and the border and title block are written with a number 7 pen. Layers dealing with sewers, drainage pipework, and manholes, however, use a pen line weight of 11.

National CAD Standards now include the AIA CAD Layer Guidelines. The diagram below illustrates AIA layer color and pen weight specifications.

Hand To CAD Services uses AIA standards for CAD Conversions and for critical infrastructure projects with utility companies and the Department of Homeland Ssecurity

For the official US National Layering CAD standards: https://www.nationalcadstandard.org/ncs6/pdfs/ncs6_clg_lnf.pdf

To purchase this US National CAD standards document:  https://www.nationalcadstandard.org/ncs6/ordering.php