How to Interpret Engineering Drawing Markups

2_Drawing Markup Redline

Throughout the design, fabrication, and construction phases of an engineering project, drawings get marked up. These markups are often referred to as markups or redlines.

Drawings will be marked up many times throughout the duration of a project. Engineers will markup drawings provided by the designers during drawing reviews.

Once the Engineers are happy with the drawings, they will be submitted to the client for review. The client will mark up the drawings provided by the engineers. Once the client is happy with and approves the drawings, the project will move into fabrication or construction.

Often times, there are changes made during the fabrication or construction phase. The changes are recorded on the drawings as markups and then incorporated into the drawings as an as-built (“as-built” linkable to our as-built blog) set of drawings. 

Here at ABM we use a standard color scheme to markup drawings. The system we use seems to be widely accepted as a standard color scheme. Using a standard color scheme helps to promote clear communication of intent across multiple disciplines and teams.

Here is an example of the markup procedure using a fabrication detail. The first step is for a Designer to submit the drawing to the Engineer as shown here.

The Engineer writes comments on the drawing following the markup color scheme. The engineer will use a Red pen to indicate all changes that are to be added to the drawing, a Green pen to indicate all items to be removed, and a blue pen to make general comments that do not get added to the drawing. The drawing gets sent back to the designer to incorporate the changes.

The designer makes changes to the drawing based on the Engineer’s comments. Once a change is made, the designer will highlight the comment using a Yellow highlighter to signify that change has been made.

The drawing is reprinted and sent to the Engineer for review. This process repeats until the Engineer is happy with the drawing.

There are many tools available to markup drawings. There are PDF programs that work on computers and tablets but multiple pens (or a multi-colored pen) and paperwork just as well.

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