Cad File Transfers

Digital File Request

NZACS members are increasingly being asked to provide ‘digital’ or ‘CAD’ files from clients and/ or contractors at the end of projects or even during the project construction period. Increasingly, electronic files are the norm at every phase of the construction period, so it is important you understand the risks associated with providing digital (and editable) information which, once it has left your keyboard, is outside your control.

Types Of Files:

Currently (2018) there appear to be 3 main types of digital files most commonly ‘requested’ during or at the conclusion of a construction contract. It is important to know which type of file you are issuing (or has been requested) and for what purpose.  Very crudely, these most common digital files are as follows:


Industry Foundation Classes file

IFC is a data model that is used to describe building data and geometry across building disciplines and across phases of the building life cycle. You can use IFC models to share data regardless of what software application they use to get their job done. IFC models contain a structures combination of geometric and non-geometric data. This data can be displayed, analyzed and modified in different ways in multiple software applications. An IFC file is an export from a BIM tool that is intended to be imported into another BIM tool, either for design coordination, phase handover or for similar data exchanges that require interoperability.  In design the main use are 3D design visualization and clash detection.


‘DRAWING’ file

A DWG is a binary file format used for containing 2D design data, originally developed by AutoCAD via AutoDesk. DWG files are basically CAD (Computer Aided Design) drawings consisting of vectors (linework) and meta-data written with binary coding. The DWG format is probably the most widely used format for CAD drawings, it shares the 2-dimensional properties of the design file with any application that supports .dwg file format. Unlike IFC it’s not used as a 3D reference document, instead its used for more simple tasks, such as tracing/ overlaying data against another consultant’s work or merging multiple 2D documents together into one document.

PDF file:

The Portable Document Format (PDF) is a file format developed in the 1990s to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. In real terms this form of file transfer allows CAD files to be easily transferred without being able to be edited. Basically, PDF has become the default format for ‘issuing’ electronic drawings and documents and is the most common form of file transfer today. Note, however, some PDF files can be editable, if allowed. Note also there are applications which can ‘convert’ PDF files into editable CAD files but the resultant 2-D ‘data’ is very limited due to the loss of all background supporting layers, objects etc.

Which One To Issue:

NZACS member must understand at the beginning of the contract what type of digital file they are being asked to provide at what stage and for what purpose. No disclaimer is bullet-proof, but it would be prudent to take sensible measures to ensure any digital file transfer is completed without unduly putting the member at risk should an issue arise in the future. Below is what NZACS would consider prudent when issuing digital files to clients and/ or contractors.

Disclaimer And Digital Files:

If a member provides a CAD file(s) we would advise taking the following steps when issuing editable CAD (.DWG or similar) files:

  • Files are DWG 2-D files stripped of all layer names/ combinations/ attachments/ links or embedded elements. IFC files are NOT to be issued.
  • All identifying logos/ title blocks/ names etc are removed.
  • All dimensions and notes are removed.
  • All bespoke 3-D elements, objects and/ or details are removed, exploded or attached. All links are removed.
  • The client counter-signs a disclaimer which may look something like this (subject to a proper legal review): At your request, and subject to your signing and returning this transfer agreement, we are providing you with editable .DWG files (CAD files) prepared in accordance with the terms of our conditions of engagement (“T&C”) with you for this project. They may be “work in progress” and/or subject to matters beyond our control and you must satisfy yourself that they are suitable for your purposes. We reserve the right to remove data not required by the T&C.  You must not use or permit others to use the data for purposes beyond the scope of work relevant to our T&C without our express written permission (not to be unreasonably with-held).  Subject to the T&C, you agree to defend, indemnify, and hold us harmless for damages and costs arising out of the modification distribution reproduction or use of these files, and you must maintain confidentiality and legal privilege where that is relevant. Any unauthorized modification or reuse of the files shall be at your sole risk, and you agree to defend, indemnify, and hold us harmless for all claims, injuries, damages, losses, expenses and legal fees arising out of the unauthorized modification or use of these CAD files. Finally, all files are confidential and may be legally privileged. If you are not the intended recipient of the CAD files, any disclosure, reproduction, copying, distribution or other dissemination or use of these CAD files is strictly prohibited. If you have received these files in error, please notify the sender immediately and delete the CAD files. Please countersign this statement and return

Further Information

NZIA Practice Note PN 6.102 provides some good guidance on how to draft a covering letter.

NSW ARB Information Sheet ‘Access to Electronic Files’ dated May 2015 also provides good advice.