Why Drawing Errors Make It Through QA/QC

Engineering teams know the importance of quality assurance and quality control (QA/QC). Drawings need to be checked, schedules need to match plans, and the information going to the field needs to be consistent.

So why do errors still make it through?

The answer isn’t necessarily a lack of expertise or attention to detail. Often, it’s the practical challenge of reviewing complex drawing sets under real-world conditions.

As projects grow, the number of sheets, references, schedules, and dependencies grows with them. Reviewers have to keep track of more information, move between documents, and complete their checks within the time available.

Even a capable team can struggle to give every sheet and every relationship the same level of attention.

Here are four reasons drawing issues can be missed.

1. Drawing sets are interconnected, but reviews can become fragmented

A drawing set isn’t simply a collection of individual pages.

Plans, equipment schedules, panel schedules, notes, and other documents contain information that needs to agree across the set. A detail on one sheet may depend on information documented somewhere else.

That creates a challenge for manual review.

A reviewer might check a plan and find nothing obviously wrong. The relevant schedule might also look reasonable when reviewed on its own. The inconsistency only becomes apparent when the two are compared.

This is where cross-sheet checking matters.

The more information a reviewer has to cross-reference, the more important it becomes to have a consistent way of checking relationships across the drawing set rather than treating each page as a separate task.

2. Time pressure forces teams to make trade-offs

Thoroughly reviewing every drawing takes time.

On a large project, an engineer may need to work through hundreds of sheets while also managing design decisions, coordination, project deadlines, and other responsibilities.

That creates a difficult choice: how much time can the team realistically devote to checking every detail?

Some firms rely on spot checks. Others concentrate review effort on areas they consider most important.

These approaches can be understandable responses to limited capacity. But they also mean that not every part of the drawing set necessarily receives the same level of scrutiny.

The challenge isn’t simply asking engineers to work harder or spend more time reviewing.

It’s finding a practical way to apply the necessary checks consistently across the work they produce.

3. Repetitive checking demands sustained attention

Consider the experience of reviewing a drawing set for an extended period.

The reviewer is comparing information, checking references, looking for inconsistencies, and moving between sheets. Much of this work requires careful attention to detail.

Now imagine repeating that process across a large package, with multiple schedules and related drawings to reconcile.

It’s reasonable to recognize that sustained concentration is difficult, even for experienced professionals.

As Arvind has described the experience, engineers know what it’s like to be deep into a QA review when their eyes start to glaze over.

That’s not a criticism of engineering teams. It’s a reality of repetitive work.

Experience and professional judgment remain essential. But a review process that depends entirely on someone repeatedly spotting every inconsistency by eye places a significant burden on individual attention.

A better process should help reviewers apply checks systematically and make the results easier to examine.

4. Review processes vary between people and projects

Engineering firms develop their own QA/QC procedures. The checks performed, the way they are documented, and the amount of review possible can vary with the project, team, and available resources.

That variation matters.

If a check is performed differently from one project to the next, it becomes harder to know whether the same level of scrutiny has been applied consistently.

A repeatable process helps establish what has been checked, what needs further attention, and where an engineer needs to make a judgment.

The goal isn’t to remove flexibility or professional discretion. Different projects have different requirements.

It’s to make routine checks more consistent, so important work doesn’t depend entirely on individual memory, working habits, or available time.

What can engineering teams do about it?

The answer isn’t to eliminate manual review. Engineers still need to interpret drawings, understand design intent, assess findings, and make decisions that require professional expertise.

Instead, teams can look at how to make their existing QA/QC processes more systematic.

Start by identifying the checks that are repetitive and well-defined.
Which relationships are reviewers repeatedly checking across plans and schedules? Which inconsistencies are easy to describe but time-consuming to find manually?

Make review coverage more visible.
Can the team distinguish between information that has been checked, potential issues that need attention, and areas that still require review?

Establish a consistent process.
A repeatable approach makes it easier to understand what was checked and to apply the same process across different drawing sets.

Use automation where it makes sense.
Automated checks can help surface potential issues and support reviewers in examining drawing information. The findings still need to be interpreted in context, and engineers remain responsible for their professional decisions.

The important distinction is between automating appropriate checks and attempting to automate engineering judgment.

They aren’t the same thing.

A more systematic approach to drawing QA/QC

Drawing errors don’t necessarily make it through review because an engineer failed to do their job.

Sometimes the challenge is the volume of information, the relationships between sheets, the time available, or the difficulty of maintaining consistent attention across a large set.

These are process challenges as much as individual ones.

For MEP engineering firms, the opportunity is to make QA/QC more systematic without adding unnecessary work or compromising the role of the engineer.

That’s where automated drawing checks can help.

At RedMark, we’re working on automated checks for engineering drawing sets in PDF format. The aim is to help teams identify potential issues and review the results, while keeping engineering expertise and judgment at the center of the process.

The starting point is straightforward: understand how reviews work today, identify where repetitive checking creates friction, and evaluate whether a more systematic approach helps on real project drawings.

Where do you see the biggest challenges in drawing QA/QC today — cross-sheet consistency, review time, or applying the same checks across every project?