LAYER NAMING CONVENTION 3

[bumpjones]

Hello,
We had an major downsizing event and I have gotten the additional work of maintaining our Autocad drawing library and was wondering "ARE THERE ANY STANDARDS OR CONVENTIONS FOR NAMING DRAWING LAYERS"

Thanks,
Bumpjones

 

[CADQUEEN]

The AIA layers are excellent in their readability. Further, the AIA layers follow an organizational structure which groups like layers together. This grouping is composed of a discipline prefix, like "A" for architecture, "S" for structural; a major group, like "WALL" for walls and "DOOR" for doors; a minor group, like "FULL" for full height, and "PRHT" for partial height; and then a status suffix, like "NEWW" for new work, and "DEMO" for existing work to be demolished. So, a door to be demolished belongs on a layer call A-DOOR-DEMO.

The recently published second edition of the AIA Layer Guidelines recognizes three positions which have shaped their formation. They are popularity, parsing by discipline, and completeness.

The standards are apparently not compatible with standards being formulated by ISO, the International Standards Organization across the great pond. However, the decision to continue with the first version was based on a polling of AIA constituency. It seems the AIA did not want to come endorse a standard which was completely different from what most members were already using. This decision must have been a tough one: a standard existed among AIA members, but it was not the standard the rest of the world was agreeing on.

The standards are also based on completeness. Layer suffixes exist for new work (-NEWW), existing to remain (-EXST), existing to demolish (-DEMO), as well as future work, temporary work, relocated work, items not in contract, and phased work. While very, very large jobs might be so cumbersome as to require all these modifiers, the desire to reach completeness with layers leads one to become layer-crazy. Layers are created which serve little purpose but to show that every thought concerning a project is manifested through layer creation. What such a system fails to recognize is that there are several methods in CAD for distinguishing one component from another. Phased work can exist in separate files. Future work does not exist. Relocated work, because it is moved, must appear twice as an entity in a drawing set, and can therefore be shown as demolished and then new work. Because existing work is drawn in one file and proposed work in another, I use the -DEMO suffix in the existing work file to distinguish demolition from existing to remain. However, no other suffixes are necessary because file differentiation separates new from existing, or one phase from another.

Deliverables is the third factor which influences CAD standards. CAD standards facilitate production of either electronic or hard copy deliverable items. This third factor ensures pragmatism an issue in the development of CAD standards. Because the main form of deliverables is hard copy, a large amount of the smart information embedded through layer differentiation is lost when a vellum or blueline is produced. Layers, then, serve two pragmatic functions: help with drafting of the various plans, elevations, and details, and help with the readability of the printed sheet, which is largely a function of line type and thickness. Layer standards should be no more complex than is necessary to accomplish production and delivery of the design.

Completeness can add complexity in wall designations. The AIA recommends -FULL be appended as a minor group tag to full height walls, and -PRHT to partial height walls. In plotting terms, partial height walls are different than full height walls because they do not show up on an RCP. In general then, I find the -FULL tag superfluous. All walls can be considered full height unless otherwise noted.

To summarize, CAD layers should be implemented if for no other reason than to practice a standard of care. The level of organization should approximate that of software programming, which CAD drafting in many ways is akin. However, an eye on the deliverables should temper the development of layer standards. To this end, the AIA Layer Guidelines serves as a method to draft with care, and with a rigor that allows human readability and an organizational completeness. The standards fail on a few concepts, such as parsing by discipline, which I disagree with, and in their completeness, which I feel is a product of their top-down development, with seemingly little input from drafting staff.

I would recommend compliance with the AIA standards.