I recently had lunch with Jeff Carmichael who works in the design and construction industry. Through our discussions, it became clear that most projects are still managed by handing PDF files back and forth between builders and owners of projects, leading to miscommunication and various issues. In an era of Building Information Modelling (BIM) where you can model the 3D elements of a building and the buildout to avoid conflicts (say, between a pipe and an electrical line), why would you still use PDFs?
His response was that PDFs provided a level of “risk management” or “risk mitigation” between the parties. This immediately made me think of Industry Standards, which are largely still distributed in PDF format despite the possibility of interactive standards. From my research, here is a breakdown of why PDFs remain king during the bid phase and how liability plays into it.
1. The Unshakeable Legal Status of the PDF
In construction law, the Contract Documents are the legally binding source of truth. Historically, signed and sealed paper drawings held this title; today, that role is filled by flattened PDFs.
- Finality: A PDF is a digital snapshot. It represents a completed thought that the design team is willing to stand behind.
- Tamper-proof: Unlike a CAD file, where a contractor might accidentally move a wall 2 inches with a stray mouse click, a PDF is difficult to alter unintentionally.
- The “Disclaimer” Culture: Often, if an architect does provide CAD or BIM files during bidding, they require the contractor to sign a “Digital Data Release”. This document usually states that the electronic files are for convenience only and that the PDFs take precedence in the event of a discrepancy.
2. The Liabilities Hidden in Live BIM/CAD Files
Handing over a live model or a raw CAD file introduces several liabilities that PDFs do not:
- Hidden Data: A 3D model might contain “metadata” or back-end calculations that the architect hasn’t fully vetted. If a contractor bids based on a hidden data field that turns out to be wrong, the architect could be held liable.
- Scale vs. Dimension: In CAD, a contractor might use a digital ruler to measure a distance not explicitly labeled. In many jurisdictions, “scaling the drawings” is a major liability risk. PDFs force the contractor to rely on the written dimensions provided by the designer.
- Software Interoperability: If a contractor opens a Revit 2024 file in a different version or a competing software, elements might shift or disappear. A PDF looks the same on every screen.
3. The IPD/BEP Compromise: Where the PDF Wall Crumbles
The “PDF-only” wall is starting to crumble in more sophisticated projects, particularly those using Integrated Project Delivery (IPD).
To manage this, teams use a BIM Execution Plan (BEP). This document defines the Level of Development (LOD)—essentially telling the contractor, “You can trust this model for its geometry, but do not trust it for the exact hardware specs”.
Why Industry Standards are still PDFs
The underlying driver for both construction documents and Industry Standards is the same: liability and risk mitigation. These points felt very similar to the discussion around PDFs for Industry Standards. We have repeatedly heard from standards bodies that PDFs deliver a similar sense of security as they are “complete” documents that cannot be taken apart. Any calculations, tables, charts or other information in these standards are written out in a way that is clear and less error-prone—even though an interactive calculator from Calcs.com from Chris Borzillo or databases of information from publishers such as SAE International or MMPDS from Batelle would be more practical.
From a Digital Rights Management (DRM) point of view, it is much easier to protect a PDF than it is to protect interactive information in a database or files with many components. Without DRM, it is difficult to see how Industry Standards can be sold without creating major “leakage” and sharing outside the authorized license holders. Some of these issues are outlined in an interesting post by Nicolas Fleury on the business challenges of Standards bodies.
In short, PDFs, while far from perfect, offer a host of benefits to standards bodies and to a certain extent, to the end user. There are reasons we still buy books, listen to full music albums or share photos—some formats are here to stay because they have a beginning, a middle and an end and can be shared as a clear distinct unit.
