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Imperial College London Estates has found it necessary to issue standards to ensure conformity and understanding of drawings

Our procedure lays out the requirements for producing standard Computer Aided Design (CAD) drawings by all of the Architect, Consultants or Contractors working on all projects for Imperial College London. The procedure contains all information required by Architect, Consultants or Contractors to standardise all drawing works produced for Imperial College London. CAD Drawings that do not comply with the Strategy will be rejected by Imperial College London.

PLEASE NOTE: As of 2018 all new projects will adhere to the revised standards as part of the new NEC contracts. On BIM enabled projects these are included within the EIR document issued for the project. All projects (BIM or not) will adhere to the relevant sections below of the College's EIR.

Information Exchange Formats
BIM and 2D Production Standards

OLD CAD STRATEGY - (Projects registered PRE 2018 ONLY)

CAD strategy


Architect, Consultant or Contractor

An Architect, Consultant or Contractor can mean any Architect, Consultant, Main Contractor or Sub-Contractor that may make any changes to the Imperial College CAD drawings or produce their own drawings for Imperial College London. Herein called `Design, Working or Record Drawings'.

Master Building Outlines

Master building outlines are a set of drawings showing only Imperial College building outlines, partitions and door and window structural openings etc. The master outlines only contain items that are not subject to change. These building outlines may be obtained from Julie Neville on +44(0)20 7594 8896. Under no circumstances shall an Architect, Consultant or Contractor change the building outline layout shown unless contracted to do so.

External Reference

An external reference or XREF is a drawing which is Imported and attached onto a host drawing. The Individual elements of this drawing cannot be altered within the host drawing, however layers applying to the Xref may be turned ON/OFF as required. Please attach any xrefs on to an appropriate layer name. Future alterations to an Xref will alter any other drawings with the same Xref attached. Xrefs should be bound to the host drawing when issues as an 'As Built/As Installed' drawing to Imperial.

Drawing production

Drawing units

All drawings shall be drawn in Model Space at a scale of 1:1 where one drawing unit = 1mm. Angles shall be shown in decimal degrees and measured anti-clockwise with 0 measured as a horizontal line drawn to the right. The preferred scales for use are: 1:1, 1:10, 1:20, 1:50, 1:100, 1:200, 1:250, 1:500. Please denote within the scale box on the title block which size paper the scale is relevant to, for example: 1:100@A1.

Drawing revisions

Drawing revisions shall be given an alphabetic issue letter which appears in the title box. Revisions to drawings shall be clouded to outline clearly the changes, and this shall be placed on its own layer called Z-000-Cloud in colour 150 (Purple). Revisions shall be described in sufficient detail to enable the nature of the revision to be identified and shall be located above the title block.

The existing whole building schematics should be updated to cater for omissions and additions. The works shall be added to the model space layouts using the same layers, colours, styles etc. as the existing services – i.e. there shall be no difference in the appearance of the existing or new services evident from the model space view. In paper space a revision cloud shall be added to identify the extent of the contract.

Text styles

The text shall be standardised to STANDARD Arial. All drawings are to have a standard text heights of 2.5mm, 3.5mm, 5.0mm and 7.0mm and a width no greater than 1 at a scale of 1:1. For example a drawing drawn at 1:100 would have a text height (in Model Space) of 250mm, and the height of the text in Paper Space would be 2.5mm. Blocks and Title blocks should be left in the text style they were made in and not changed to Standard Arial.

Pen Settings

If recommended pen thicknesses are not used a .ctb file should be supplied with the drawing files

It is recommended that all the master outlines (XREF0 should be in colour 8 (grey) when attached to M&E services drawings to emphasise the M&E services.

The use of the colours and pen thicknesses to highlight various services and elements are shown in section 8.

Line Types

Standard Autocad line types must be used. Site survey drawings showing main service supply routes may use special line types such as:

  • GAS___GAS

These special line types must be supplied with the drawing files.

Master outlines (external reference)

Model Space/Paper Space

Master Outlines will be attached to drawings as Xrefs. All Xrefs will be placed into the drawing in a view which will allow the drawing to stay at its original scale by zooming to its scale within the view. Under no circumstances should the Master Outlines (Xrefs) scale be increased or decreased by the Architect, Consultant or Contractor, other than by Zooming. Model Space/Paper Space should be used on every drawing. All Master Outlines, text, symbols, charts, diagrams etc. will be added to a drawing in MS (Model Space). All title blocks, Legends, Revision notes, overall general notes etc. Will be added to a drawing in PS (Paper Space).

Drawing numbering

To enable efficient management of drawings, all drawing numbers must be of a similar format.

All drawings must have an Imperial College London project number placed on the project line of each title block (see example below) and Building Code as part of the drawing number.

The drawing number only appears in the title block and is not to be confused with the filename which is a shortened version. A drawing filename comprises the drawing number without the Building Code prefix. As an example, in the table below the drawing number of EENG/L7/E/RD01 will condense to a filename of L7ERD01. This filename should also be used when saving t he file.

All drawings shall wherever possible be related to a Service Code. The only exceptions being drawings of a general nature which are applicable to more than one Service Code.

Drawing numbering

ExamplesBuilding codeLevelService codeDrawing No. 
Record drawing No. EENG L7  RD01  RD 
Drawing layout No. EENG L7 0001 
Drawing schematic No.  EENG SCH  E 0001 
Drawing diagram No.  EENG DIA 0001 
Drawing section No. EENG SEC  0001 
Drawing elevation No.  EENG ELEV  0001 
Drawing File Name   L7 E 0001 A
Drawing Numbering

All drawings should have a related Service Code. Drawings which are applicable to more than one Service Code will follow the example below.

Where an item of equipment represents an interconnection between two separate disciplines, for example a fire alarm interface to an access controlled door, the item should be included on both drawing on the most appropriate layer. Again in the above specific example, the interface being primarily a fire alarm device should appear on the F-671 layer, but on the "F" and "S".

Service codes

Building outlines A Data telecoms V
Public health (covers drainage, rainwater) P Security (covers access control, CCTV) S
Mechanical (covers ventilation, A/C, LTHW, CHW, H&CHWS) M Fire F
Electrical (covers power, lighting, containment) E General Z
Service codes

Important numbering issues to understand:

  1. The RDxx counter will reset to RD01 every time the Level or Service Code changes. So there would be as an example: EENG/L6/E/RD01 and EENG/L7/E/RD01.
  2. Layout drawings should not cover more than one level, so EENG/L6&7/E/RD01 would not be permitted. Any other drawings ie Sections and Details covering more than one level would use a general level LZ so EENG/LZ/A/RD01.
  3. Similarly drawings should not cover more than one service, so EENG/L7/E&F/RD01 would also not be permitted.
  4. Drawings should also not cover more than one building, so ACEX&BONE/SCH/E/RD01 would not be permitted. If a system does cross building borders, two drawings should be generated, one for each building, with cross references to the other drawing at the continuation point. Just as with large buildings requiring several drawings per level.
  5. Each drawing must be uniquely presented as its own file. The use of multiple drawing tabs in a single file is not permitted as multi filename problems would ensue.

A drawing filename comprises of a standard set of eight characters which are the drawing number without the building code prefix.

All drawings shall have an Imperial College Project Number, placed on the project line of each title block and Building Code as part of the drawing number (see above).

  • Building codes contact: Julie Neville; tel: +44(0)20 7594 8896.

Room numbering and level naming

All Room numbering and Level naming must be allocated by Imperial College London and is managed by the College Space Management Team.

Level names to be used (CAD file reference to be used): 

  • Level Sub Basement = (LSB)
  • Level Basement = (LB)
  • Level Lower Ground = (LLG)
  • Level Lower Ground Mezz = (LLGM)
  • Level Ground = (LG)
  • Level Ground Mezz = (LGM)
  • Level 1 = (L1)
  • Level 2 = (L2) etc.
  • Level Roof = (LR)

Please do not use “First Floor” “Second Floor” etc. Please only use the term level.

The College room numbering system is to be used to ensure accurate location of equipment and/or systems operational details. Individual building room numbers are used for identifying the location of equipment and/or systems operational details in connection with the following mechanical, fire, security and building management services. The systems include:

  • Fire alarms and detection.
  • BMS Controls.
  • Security (access control, intruder alarms, CCTV).
  • Electrical distribution board/circuit references.
  • Mechanical equipment locations (i.e. fan coil units).

Room numbers are also used for systems certification and maintenance asset schedules. It is the responsibility of the Project Manager to ensure that the correct room numbers are advised to all parties involved.


All room numbering and level naming is managed by the College Space Management Team. Requests for new or revised room numbering/level naming should be made to the Space Management Team via the Estates Customer Service Centre.

All proposed space changes including refurbishment works are to be referred to the Space Manager via the Customer Service Centre.

All room numbering and level naming for new buildings and modified space must be allocated by the College's Space Auditor. Requests are to be made at Stage 3 of a project and be accompanied with a full set of general arrangement drawings issued to Building Information Team, in line with this CAD Strategy. If there are any further changes within the project which may affect the previously approved ICL numbering, further drawings shall be sent to the Space Management team for revised room numbering to be re-issued.

Requests are to be accompanied with the Space Change Form and sent to Space Manager, Ghada Al-Madfai.

Drawing frame setup

Title Blocks

All drawings shall be drawn within the bounds of one of College drawing frames provided to suit the scale used. College drawing frames are downloadable from the link below. The drawing frames are scaled at 1:1 and comprise of: outline frame, title block, revisions block and College logo. There is a blank space allocated for any companies/departments wishing to add logo's etc. All drawings will have a title block, which will be inserted into a drawing in Paper Space at an origin of 0,0. While in paper space a view must be made up under a layer called Z-000-View so that any Xrefs or drawings will be in Model Space to scale. All title blocks will be in an attribute format allowing all information to stay the same, but with editing facility. Additional boxes may be inserted if required and those parties wish to include their own drawing or project number/reference.

Example of an AutoCAD Title Block

Use of standard layering procedures

Naming convention

A standard CAD layering system is necessary to enable consistent drawing production from a wide variety of sources and services. Imperial College London follow the BS 1192 part 5, please see the link below for the layering standard. In order to facilitate this The College requires that the following process is adhered to.

  • Additional layers beyond those listed do exist within the British Standards, but are not deemed relevant to ICL projects. New layers should NOT therefore be created using what may appear to be "spare" numbers.
  • Where ICL layers do not seem suitable for a particular item of equipment/system, the most appropriate group master layer (i.e. the layer ending in "0") should be used.
  • This master layer should NOT however be used to contain any services which clearly belong to a specific layer.
  • Please ensure that duplicate layer names are not present on drawings.

To ensure correct layering the College requires that the following process is adhered to.

  1. Project Manager requests existing college floor plan in .DWG format from CAD Manager.
  2. Project Manager forwards floor plans to appropriate Design Team/Project Team member.
  3. Design Team/Project Team amend drawing to show new General Arrangement in format as received.
  4. Amended General Arrangement drawing is returned to engineering team to allow College drawing database to be updated.

All layers should be colour by layer, and all corresponding text and leaders should be on the correct services layer name with an extension of a "T". i.e. Service Layer = A-320, Text layer = A-320T. General text layers should only be used in the case of charts, titles, legends and notes column.

Use of standard symbols

Mechanical and electrical symbols

British Standard CAD symbols are considered too detailed to be successfully used on drawings at scales greater than 1:100, particularly electrical BS symbols. Therefore simplified versions of the BS symbols have been developed as the standard set of College symbols as follows:

Any symbols not allocated by the College should not be used, unless authorised by Building Information Manager who will register the symbol within the set.

To begin the process of achieving a set of standard symbols a schedule of mechanical and Electrical (M&E) symbols are presented in the link below.

All symbols inserted into model space will need to be scaled in at the scale of the drawing apart from linear & modular fluorescent luminaires. These should also be inserted on the appropriate layer name.

Symbol download

Submission of record drawings

It is the responsibility of the main contractor to provide all As Built/As Installed drawings to the Records and Records and Archives Officer (Estates).

The Project Manager is responsible for ensuring all drawings are delivered to the Records and Archives Officer (Estates).

As Built/ As Installed drawings shall be submitted 2 weeks prior to completion of all projects in accordance with the ‘Works Information Preliminaries section 5’.

Please ensure that .dwg files containing xreferences are ‘Bound’ into the drawings as described in section 5.1.

Please ensure that the GA floor plans within the set are clearly marked as GA's. All drawings are to be to an appropriate scale and clearly marked as As Built with RD in the Revision box.

Please ensure that all drawings have been produced to the College's CAD procedures.

All drawings for the project to include but not limited to: GA's, sections, elevations, details, schematics and services drawings should be in both .dwg and .PDF formats electronically on CD and produced in accordance with the Building fabric manual production guidelines (pdf) and Mechanical and electrical O&Ms production guidelines (pdf).