A drawing revision is a formal update to a construction drawing whenever a new bulletin, addendum, or design clarification is released. Each drawing revision is designated a unique revision number or letter. The revision number or letter helps the people using the drawing identify which version they are currently using.
The revision tracking system is the same on most drawings, but some drawings employ different tracking systems. Most tracking systems consist of a triangle or number placed in the title block, and that number is also shown in a revision log placed along the bottom or side of the drawing. The revision log also shows which area of the drawing was revised with a cloud around that area.
The revision log also should be read thoroughly, as it shows the revision number, the date the revision was made, and a description of the revision (sometimes authored). This log is a great tool to understand the past revisions of each drawing.
A few practical rules experienced field staff follow around revisions:
- Always check the revision number in the title block before relying on a printed or downloaded sheet
- Cross-reference the revision log against the bulletin or addendum log to confirm what triggered each change
- Never assume a cloud captures every change; read the full revised area, not just the clouded portion
At an advanced design stage, one drawing may go through more than 6 or 7 revisions before construction documents are finally drawn. Real coordination and pricing work occur behind the scenes, even for minor changes.
Even though superseded drawings require real coordination and pricing work, they should stay in the project record, as disputes may arise over what the drawing portrayed at a specific time in the project.
Revisions are sometimes missed by the drafter making the revision, especially when the work is being done under time pressure during the last stages of design, and a drawing may contain real changes that are unmarked. This is one of the stronger arguments for periodic full comparison against a prior baseline rather than relying purely on clouds to catch everything; the cloud is a helpful convention, not a guarantee.
A small but telling detail worth watching for: when a revision log entry’s description doesn’t quite match what actually changed on the sheet, which happens more than it should when a drafter updates the drawing but writes the log entry from memory rather than double-checking it against the final revised sheet before issuance.
