It is important when producing drawings that all lines, blocks and annotations are assigned to the correct layers and not just to one layer (i.e. layer 0) or random layers within a drawing. This needs to be followed by everyone who produces drawings for that organisation (internal and external).

Now I have personally developed and set up many CAD standards over the years for many organisations I have worked for and with. Most recently I have been working with one of our clients who would like to align their CAD and modelling standards to the latest industry standards. As part of this we looked at CAD layering best practice and what should be applied as their standard. 

If we are to align to anything, it is really a good idea to align to a standard which has been set out to industry best practices which will be produced by either the British standards British (BS) or International (ISO) standards.

Layer Naming Standards Past and Present

BS 1195-5:1998 Construction drawing practice – Guide for the structuring and exchange of CAD data

Although this has been withdrawn you can see where ISO 13567-2:2017 has derived from. It states that layer names should be divided into fields of which some are mandatory and others optional.

• Agent Responsible – This could be the Architect, mechanical engineer, civil or structural engineer, etc.
• Element – This is an element code from a recognized classification system such CI/SfB table 1, CAWS, or Uniclass
• Presentation – Model related character such as dimensioning, text, hatching, etc.

Agent Responsible_Element_Presentation

BS 1192:2007 + A2:2016 Collaborative production of architectural, engineering and construction information – Code of practice.

BS 1195-5:1998 later became BS 1192:2007 which still followed a similar distinguished layer naming container standard. The classification system was Uniclass.

The AEC (UK) Protocol for Layer Naming was written to help with the implementation of layer naming in the UK. You can still download a free copy from AEC (UK) CAD & BIM Standards Site, but this hasn’t been updated for a number of years now.

BS EN ISO 13568-2:2217 Technical product documentation – Organization and naming of layers for CAD

If you are following BS EN ISO 19650-2:2018 here in the UK then as part of the national annex NA it refers you to BS EN ISO 13568-2:2217 for naming CAD layers.  It is as before but does not state what the Agent characters are just there are a maximum of two required. Which then you need to either make your own up or use what was maybe previously set out. The classification system used here in the UK is Uniclass 2015. The NBS currently manages and maintains these classifications tables.

Agent Responsible_Element_Presentation

What do you align your CAD layering to?

I was interested to understand what everyone else across the industry (UK) was aligning their CAD layering to, if any. So in May (2021) I ran a poll on Twitter to ask people do they align their CAD layers to BS EN ISO 13567-2 which is set out as a required standards to following in BS EN ISO 19650-2 National Annex NA (UK). Now I only had 24 votes but to see the result it does concern me a little when this is a standard which everyone should know is there for them to use.