Drawing Revision
A formally issued change to a drawing, marked so everyone can see what moved.
Quick Answer
A drawing revision is a formally issued change to a construction drawing after its earlier release. The change is marked with a revision cloud and delta symbol, and logged in the title block's revision block with a number, date, and description. Revisions show what changed, but unclouded or missed changes are a major source of pricing errors and rework.
The Full Picture
Drawing revisions exist because designs keep changing after drawings are issued. Owner decisions, coordination fixes, RFI answers, code review comments, and value engineering all alter the documents. Every party pricing or building from those drawings needs to know exactly what changed, or they'll price and build from superseded information.
Mechanically, the design team edits the sheet, draws a revision cloud around each change, tags it with a delta symbol carrying the revision number, and adds a line to the revision block with the date and a brief description. Revisions are typically issued in packages, such as addenda during bidding, bulletins or ASIs during construction, or a new design milestone set. Standards like the U.S. National CAD Standard define conventions for revision marking and sheet organization.
In practice, the hard part is the review. An estimator receiving a 300-sheet revised set needs to know what changed and what it costs. Clouds help, but designers sometimes miss clouding a change, and a small note edit can carry a large cost. That's why teams overlay old and new sheets to find every difference, not just the clouded ones.
In preconstruction, drawing revisions hit hardest between design milestones and during bidding. Each new set can move quantities, scope boundaries, and subcontractor pricing. A GC that doesn't catch a revision may carry a price based on old drawings into a GMP or lump sum. Good revision control means knowing which set every estimate and bid was based on, and reconciling the differences each time a new set arrives.
Real Examples
Common Misconceptions
People assume: If it isn't clouded, it didn't change.
Actually: Clouding is manual and imperfect. Changes are regularly left unclouded, especially small note, dimension, or schedule edits. Relying only on clouds is how teams price from outdated information; overlay or automated comparison catches what clouds miss.
People assume: The latest revision number tells you everything about the set.
Actually: Sheets in a set revise independently, so one set can mix sheets at different revision levels. Teams need to track the revision status of each sheet, not just the set issue date, to know what their estimate was based on.
Does MeltPlan Solve This?
Yes — direct fitYes — Drawing revision tracking is a core part of what MeltPlan's Design Review does. It compares drawing revisions and flags what changed between sets, including changes that weren't clouded, so estimators and precon teams can see scope and quantity impacts without manually overlaying every sheet.
Find every change between drawing sets →Frequently Asked Questions
What is a drawing revision in construction?
It's a formally issued change to a drawing after its earlier release. Changes are marked with a revision cloud and a delta symbol, and recorded in the sheet's revision block with a number, date, and description so everyone can identify the current version.
What is a revision cloud and delta?
A revision cloud is a scalloped outline drawn around the changed portion of a drawing. The delta is a triangle symbol next to it carrying the revision number, which ties the change to the matching line in the revision block.
How are drawing revisions issued?
Usually in packages: addenda during bidding, bulletins or Architect's Supplemental Instructions during construction, or a complete new set at a design milestone. Each package lists the revised sheets.
How do you find all changes between drawing revisions?
By comparing old and new sheets directly, either with manual overlays or with automated comparison tools, rather than relying only on revision clouds. This catches unclouded changes that can affect quantities or scope.
Why do drawing revisions matter for preconstruction?
Estimates, bids, and GMPs are based on a specific set of drawings. When a revised set arrives, scope and quantities can move. Precon teams need to know exactly what changed to update pricing and avoid carrying outdated numbers into a contract.