AEC definitions
Drawing coordination is the work of making every discipline's sheets describe the same building. Architectural, structural, civil, and MEP drawings are checked against each other, and against the specifications, so a duct, a beam, a ceiling, and a door are not fighting for the same space.
Definition
Coordination happens during design, before the set is issued for construction, and it continues when addenda and ASIs change the documents. MEP coordination is the part that overlays mechanical, electrical, plumbing, and fire protection. Drawing coordination is the wider pass: structure against architecture, site against floor plans, schedules against elevations, details against the plans they are called from. A clash report is one tool inside that work. It is not the whole job.
In depth
A duct through a beam is an MEP coordination problem and a structural one. A door schedule that does not match the plan, or a floor elevation that does not match civil, will never appear in a duct-and-pipe clash run. Drawing coordination is the review that catches those.
Teams that buy a clash report and call the set coordinated have finished one slice. The sheet-to-sheet pass still has to happen, because the contract drawings are what the builder prices and builds.
Consultants draw on the architect's background. If that background moves after the engineer has routed the mains, the overlay is already stale. A coordination meeting without a frozen background produces comments against a set nobody is holding.
Publish the background date on the exchange. Reviewers should reject a coordination set whose architectural sheets are a revision behind the model they were told to use.
Grid to grid. Floor-to-floor heights against sections and against the structure. Rated walls against the penetrations drawn by each trade. Ceiling heights against the deepest system. Schedules against the tags on the plan. Details against the callouts that point at them.
Specifications belong in the same pass. A drawing that shows a product the spec excludes, or a spec that requires a clearance the plan does not leave, is a coordination miss even when every model is clash-free.
A coordination meeting should close items, not tour the model. Each open item needs an owner, a sheet, and a date. Items that change cost or scope leave the meeting as an RFI, an ASI, or a proposal request, not as a verbal agreement.
Minutes that say 'mechanical to adjust' without a dimension are how the same clash returns at the next issue. Write the decision the way it will be drawn.
Addenda, ASIs, and bulletin revisions reopen the overlay. A structural revision that deepens a beam after the mechanical set was issued is a new coordination problem, even if both sheets are stamped.
The contractor's coordination drawings, produced during construction, are a different document. They show how the trades will fit in the field. They do not replace the design team's duty to issue documents that agree.
Examples
The architectural reflected ceiling plan shows a 9 foot ceiling. The mechanical sheet routes a duct that needs 24 inches clear below the beam. Coordination drops the ceiling or reroutes the duct before issue.
The door schedule lists a 60-minute door. The plan shows that opening in a non-rated partition. The tag or the wall type changes before the set is issued.
An ASI moves a shear wall. The electrical one-line and the architectural plan are both revised, because the panel location sat on the old wall.
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