Every engineer I’ve ever worked with thinks they write good documentation. Almost none of them do.

Here’s the problem: they write docs for themselves. They write what they would need to remember. But documentation isn’t a personal note-taking system. It’s a communication tool for people who don’t have the context you have.

Who Actually Reads Your Docs

Think about who will read your design documentation:

Future you — who won’t remember why you chose that motor driver in six months.

The manufacturing team — who needs to build 10,000 of these without calling you for every question.

The FDA reviewer — who needs to understand your design rationale without a phone call.

The next engineer — who inherits your project when you get promoted or leave.

None of these people have the context you have right now. None of them sat through the design reviews. None of them debugged that weird noise issue at 2am.

The Test

Here’s how to know if your documentation is good enough:

Could someone rebuild this from scratch using only what’s written down?

Not “could someone understand this if I walked them through it.” Could they do it cold, with no access to you?

If the answer is no, your documentation has gaps.

What Good Docs Look Like

Good documentation answers three questions:

  1. What — What did you build? What does it do?
  2. Why — Why did you make the choices you made? What alternatives did you consider?
  3. How — How does someone use, test, or modify this?

The “why” is where most engineers fall short. We document the what. We sometimes document the how. We almost never document the why.

But the why is what matters when something goes wrong. The why is what helps someone make a good decision when the requirements change. The why is what separates maintainable engineering from technical debt.

The Business Case

Bad documentation isn’t just annoying. It’s expensive.

  • Manufacturing holds because someone can’t interpret a drawing
  • Regulatory delays because the design history file has gaps
  • Rework because the next engineer didn’t understand the constraints
  • Tribal knowledge that walks out the door when people leave

Every hour you spend on good documentation saves ten hours down the road. Usually more.

At Expertise Engineering, we build design controls and documentation from day one — not as an afterthought before regulatory submission. Let’s talk about your project.