Guide to CAD Layering Standards

A layer in cad is a way to differentiate between the different lines that are drawn on a page. The layer can be assigned properties such as linewieght, line type and colour and can be made visible or hidden, amongst other things.

You can use layers in a drawing for each different object type or construction element. For example, you can assign all objects or lines that are walls to a “Wall” layer. All sanitary fittings could be assigned to a ‘Fittings’ layer. Windows can have their own layer, furniture can have its own layer and so on.

Layers should be used in every drawing, no matter how large or small the project. If you are an architectural practice it is important to adopt a standardised system, or stick to a standard set of layers if you are a student, not only for good practice but also because layering your drawings can save you a huge amount of time.




 

Why we should never draw everything on Layer 0!

 

Layers allow us much more control over a drawing, and ultimately allow us to save time and money. By using a good layering system we can allocate properties to a layer and ensure the appropriate element is assigned to that layer. If later we decide we want to amend the properties, we don’t have to go through and change each individual line, we just have to change the layer properties and all the changes will appear on every line on that layer.

In AutoCAD layers are also very useful for setting up layouts and plot sheets. They allow us to control what information is viewed on different drawings. For example, on a 1:200 site plan, we would only want basic elements to be seen, so the layers that are not necessary can be switched off in that particular viewport. We would keep landscaping layers switched on, but we would turn off mechanical and electrical layers, or annotations that would be better suited to a more detailed plan, for example.

Another benefit of using layers is that you can select and modify items in bulk on a particular layer. Instead of individually selecting items that you wish to copy or amend, you can quick select all items on a layer (if the drawing has been layered correctly).

Standard Cad layers

So, I hope I have convinced you that using layers is a fundamental part of the drawing process. The next question is, what layers should I use?

There are a few different classification systems available, and this article is focussing on the use of layers in the UK. From the research I have carried out, the CISFB system which has been used widely, lacks layers for more modern systems and has resulted in practices having to modify the layering system which has created a non standard format. The Uniclass system is a little more complicated, and that has been used as a basis for the AEC UK Cad Standard. This standard was developed from 2001 onwards and provides more up to date CAD usage.

You can download the full document here: Version 4-0-2 is the reference document I used for this article.

What the layers stand for:

A layer name can be broken down into fields, these fields classify the layer.

Field 1: Role

Field 2: Classification

Field 3: Presentation

Field 4: Description

Field 5: View – optional

The full details of each field can be downloaded in full from the link to the AEC [UK] cad standard document. Here I will provide an overview to the codes for each field.

 

Field 1

Role

 

The letters define the author, or owner of the data. This therefore allows various disciplines to use the same element codes all within one drawing while still being able to differentiate between the layers.

Field 2

Classification

The element code describes the building element or component. It uses the single Uniclass 2015. It is possible to break down these codes into very detailed representation of building elements, but often it is acceptable to group items together into broader terms. For example, a curtain wall layer is Ss_25_10_20, but this could be denoted as Ss_25_10 which is the general code for walls.

The prefixes of these codes refers to:

SL – Spaces/locations

Ef – Elements / functions

Ss – Systems

Pr – Products

Z – non physical elements

In simple architectural terms, Ef might be used for general CAD work, Ss for detail work or components, and Pr for fit out or components that are produced. The best thing to do here is browse through the different categories, link below, to give you an idea of the different classifications in each category and when they would be used.

There is a vast list of different element codes, possibly too many…? So for the purposes of clarity, I have selected a few of the more common layer classifications to demonstrate here. Most practices would select the layers that they use regularly and create a template based on those common layers, rather than use the entire list to create a bulky file, and plenty of time wasted searching for the correct layer to use.

Access the full list of all the classification tables from the NBS website here.

An example of some of the more common element codes are listed below:

The Zz category provides a layer for trees and planting which can be confused with the same in the Pr and Ee sections. The Zz tree and planting can be used for generic tree placement, and aesthetic presentation to enhance a drawing, for example an elevation or visualisation model. The Ef section would be used for generic plants in the design, and Pr for defining detailed vegetation layouts or landscaping works.

The Ef classification list is quite limited, but this allows for a more simple use of the layers at early design level, and moving on to the Ss classification as more detailed design commences.

[in 2016 the classification codes were changed quite significantly, and in my opinion have become a bit more complicated than they used to be. I still use the older system for some of the architects I work for, and for my own projects, not because I don’t link change (…!) but because it does seem a lot more intuitive and user friendly. These new classification codes take a bit of time to get used to.]

Field 3

Presentation

This field indicates the type of CAD data associated with the element.

Field 4

Description

These are used to describe the element of the layer, as seen in the previous table for Field 2.

 

Field 5

View

These are added to part of the user description field and provide information as to how the elements are shown.

This field has become optional over time – I don’t use it myself.

Examples:

So with all that said and done, lets take a look at some examples of the layers:

 

List of the common layers:

 

The key to working with all these layers is having a good template set up. This means that when you start a new drawing or project you can quickly go to your template and get started with the correct layers, rather than setting up a new drawing every time.

 

I have put together a list of the most common layers that I would use, keeping it to a minimum where possible. I have created a cad drawing with these layers and it is available to download. The cad drawing is a normal dwg file but can be saved as a template if you wish. All the layers are saved – with no properties assigned, that is the linetype, line weight are all by layer, and the colour for each layer is set as white. It is simple to go through and assign colours to each layer to correspond with your own plot style. Feel free to download my layer template for your own use.

 

Download CAD Layer Template

I hope that this article has helped clarify the cad layering standards that are currently used today, and that the template will be useful to you. Links below to some of the reference documents that provide a more in depth look at the layering standards, classifications and codes.

If you have any questions please feel free to drop me an email or comment below 🙂

References:

Download the full document AEC UK Protocol for Layer Naming here

View the AEC UK standards website here

Access the full list of all the classification tables from the NBS website here




SaveSave

SaveSave

Other recent posts…

Permitted Development Rights for House Extensions

Permitted Development Rights for House Extensions

Introduction to Permitted Development Rights When extending a house in the UK, understanding Permitted Development rights is essential for architects and homeowners alike. These rights allow certain building works and changes to be carried out without the need for a...

Detail Library – New Details March 2024

Detail Library – New Details March 2024

New Details This month we are excited to share another set of details that have been requested regularly by our members. This set consists of external wall insulation details. In this set we explore a solid blockwork wall with 190mm mineral wool insulation and a...

Understanding and Applying Architectural Parti in Design

Understanding and Applying Architectural Parti in Design

In architecture, the term "parti" refers to the central idea or concept of a building design. It's essentially the starting point or organising thought that guides the design process. The parti can be a specific shape, a structural system, a key relationship in the...

22 Comments

  1. Hi,
    Thank you for your post of ‘ Guide to CAD laying Stander’s’. But actually it’s not opening…

    Reply
    • Can you explain what is happening when you try to open it, what version of CAD you have and any other details that will assist me in helping you? Thanks

      Reply
  2. Actually it’s not opening, i am using AutoCAD 2016 version.
    When i click onto the page it’s not forward to next page.
    Send me the template to my email id.
    surajpatole1477@gmail.com
    You are doing great work. Keep it so many people will be learning more about this.

    Reply
  3. Actually ypur post is not displayed in my Mobile view.
    Is it only open in computer??

    Reply
  4. Emma, best wishes for 2020 new year.

    As usual, your information is always useful.

    Best regards and thank you very much

    Reply
    • Thank you 🙂

      Reply
  5. Hi there, thanks for this article – great stuff.

    I’m unsure when this was written, but notice you used ‘Sec’ rather than ‘Cut’ – was this based on an older AEC document, or maybe a conscious decision to use a slightly different terminology?

    Also note that the Ef Uniclass Table is listed as EF on the Uniclass / NBS website, but the latest AEC doc (4.1) still lists it as ‘Ee’ for elements (I recall Ee was changed to EF around 2016?).

    A standard set of layers for each discipline would really help ‘standardise’ the standards, and I think this is a great start.

    Unfortunately I feel there’s some ambiguity within the industry around which codes are to be used from Uniclass.. often there are multiple Uniclass codes which could be applied to the same layer. I understand EF takes precedence quite often (depending on the RIBA work stage I presume) but without a published set of layers for each discipline, even with the guidance published so far, I fear there is scope for variation on the standards, defeating their purpose! A CAD Template similar to yours is a great addition, maybe in the future AEC will consider publishing their own CAD templates, in addition to the BIM Protocols etc.

    Reply
    • Thank you for your comments Rich, much appreciated.

      Reply
  6. Hi Emma, would you suggest the same layering system for a 3d model as well or is there a different one for that? if there is a different one, would you be able to create a tutorial for that too?
    Thanks,
    Sam

    Reply
    • Hi Sam, This is a good question. It is really important that 3d work is just as organised as 2d, so it is certainly beneficial to be strict with layering. However, I am not aware of a standardised 3d layering system (although the likes of Revit and ArchiCAD would use the regular layering system despite the fact you are drawing in 2d and 3d). SketchUp and other visualisation based work can also adopt the standard layering system perhaps with a suffix to denote 3d. I think it is down to the level of detail of the drawing and the required outcome, whether it is a simple visual or a full BIM model.

      Reply
  7. Very useful

    Reply
  8. I have used your (FIA) standards for years. However all my layers begin with A*** ie.,
    A000 – Demise,
    A000G-Section,
    A000H – Hatch,
    A001D-Dimensions
    A001T-General Text
    I know I have taken this information from your website, but I am unable to find it. Can you help please?

    Reply
  9. Can someone please explain to me the numerical in the description? What do they mean? are the Hue values or RGB values? This is a great article, but what about color designation?

    Reply
  10. How do you differentiate in the layer name between a line type viewed on plan and one in section, or hidden beneath something else. You would need to apply different line thicknesses and line types. For example, how would you name “A-Ef_20_05-Walls” in those different situations? Thanks very much.

    Reply
    • Hi Chris,
      We usually use the same layer on a plan and on a section/elevation, so for example, A-Ef_20_05-Walls would be used for walls on plans sections and elevations. This depends on the complexity of the project and different studios practices. On simple projects there is usually no need to create a completely new set of layers for plans/sections/elevations. Hope this helps.

      Reply
      • How do you differentiate between the different linetypes, i.e. thicknesses that you will require for sections, elevations, plans etc. then?

        Reply
  11. I suppose this is because you are using .stb files rather than .ctb files to print? Otherwise you wouldn’t be able to vary between the line thicknesses.

    Reply
    • no we use .ctb files to print. A wall in plan is usually represented with the same line thickness as a wall in elevation, so there is no issue with using the same layer.

      Reply
  12. Hello,
    Thank you for the detailed artice.

    My question is –
    How do you give these different layers, different graphic representations at different scales?
    Is there another system of subdividing these into lets say – 1:200 scale general plan an a 1:20 Detail plan?

    Reply
    • Hi Daniel,
      We wouldn’t recommend having separate layers for different scales, it would get very confusing and you would end up having hundreds of layers. There is a setting in autocad that allows you to scale line weights, essentially scaling the line weight to suit the scale of the plot. You can find this tick box when you have the plot window open.
      If you need further assistance, please don’t hesitate to email me at hello@firstinarchitecture.co.uk
      Thanks, Emma

      Reply

Submit a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.