Implementing the BS1192:2007 Layer Standard

Whilst for many the perception of BIM was that there was no more need for Layers the reality is quite the opposite. The current British Standard for CAD Layering within the UK is BS1192:2007. Where specific BIM software does not support Layers then on export to CAD systems it must produce CAD data on the relevant BS1192:2007 layers.

This page provides some guidance on the implementation of the BS1192:2007 Layer standard, but for a more detailed description please refer to either BS1192:2007 itself or the supporting documentation produced by the BSI and links can by found on the British Standards pages on this site.

BS1192:2007 allows for the following fields to be included within any Layer Name:-

Field   Role   Classification / Element   Presentation   Alias
Name   A - G23 - M2 _ Stair
Example   Architect   Stairs (Uniclass)   Model Graphics   Text

There are various methods of implementing the Layer standard within BS1192 which has led to inconsistences.

Therefore to aid with a common approach CPIC have provided a tool on their Web site to enable a common approach. This tool can be found at


DOWNLOAD - Layer Conventions Document and Supporting files

Oakley CAD Services Ltd have produced a comprehensive guidance document along with supporting Revit Export Text files and AutoCAD Architecture Layer Keys for compliance with BS1192:2007 and Uniclass Version 1.4



BS1192:2007 Layer Fields Explained

There is often misunderstanding regarding the definitions of the various fields within BS1192;2007 and other standards, with some implementations increased this misunderstanding. There is a brief discussion below regarding how the fields in BS1192 are intended for use to ensure true compliance.

'Role Field’

‘The Discipline who is the owner of the information’

There are specific implementation differences between fields such as 'Role' in the UK and 'Discipline' in the USA; Within BS1192:2007 the 'Role' field signifies the Author or Owner of the information. Therefore when an Architect draws a column the layer 'Role' field must be designated with the letter A for Architect. In the USA the Layer Field refers to the 'Discipline' having responsibility for the object. So in the USA the Architect would draw a column and the 'Discipline' field would be designated S, passing the responsibility to the Structural Engineer.

In the UK each discipline only draws on the layers where the Role Field designates their specific discipline. Therefore anything an Architect draws must be on a Layers commencing with the letter A.

Classification / Element Fields

BS1192:2007 mandates the use of Uniclass as the classification system to be used within Layer names. The original implementation of the Element fields within Uniclass meant that often the use of concatenated Uniclass codes was required in order to classify specific elements.

CPIC have therefore carried out additional work within this area and have recently published version 1.4 of Uniclass for the Layer Generator. This unifies tables G (Elements for Building) and H (Elements for Civil) into one combined table to enable the classification of elements across both Building and Civil, whilst also removing the need for concatenated codes. There has also been work on Table Z which provides a table for CAD specific classifications.

Presentation Codes

BS1192 allows for a definition of the graphics to be used to represent an object in either a single or two letter codes. Where graphic representations are to be kept simple then the single codes as defined within BS1192:2007 should be used.

Where there is a specific requirement for control of more complex graphics then the following 2 letter codes may be adopted. This allows for the separation of graphics forward, below and above the cut planes as well as for hidden objects within these views as defined within BS8541-2:2011.

Presentation codes:- 

Presentation Code


Line Type


Annotation (Tags, Arrows, etc.)









Model related graphics



2D Model  graphics



3D Model graphics



Model Analysis



Model Cut plane (Section / Details /Plan)

Thick Line


Model Grids (Grids, Reference planes, Reference Lines



Hidden lines, Items Hidden beyond cutting plane

(BS8541-2:2011 item 1.304)

Hidden line


Model Forward. Items that need to be shown forward of the cut plane.

Fine Line


Model grids (Grid references, reference planes, reference lines)  


Model Hidden for Hidden lines, items hidden beyond cutting plane

(BS8541-2 : 2011 item 1.304)



Model mirrored / reflected information (Ceilings, ductwork etc...)  


Model Non visible elements , Behind / above cut plane

(BS8541-2:2011 item 1.302)

Dashed dot dot line


Model Visible items Behind / above the cut plane

(BS8541-2:2011 item 1.301)

Dashed dot line


Plot /Page related graphics





For Single Character codes please refer to BS1192:2007 Table 15. 


Description code to assist Layer Identification

The purpose of the Alias fields is assist the identification of the building elements defined by the classification system. To ensure the consistent use of the Alias field CPIC have provided a standard list of Aliases to be used with each of the Uniclass classifications.