What Is Revision Cloud in Construction?
Definition
A revision cloud is a cloud-shaped boundary drawn around an area of a construction drawing that has been changed from a previous version. Revision clouds visually highlight modifications so that anyone reviewing the updated drawing can quickly identify what is different from the last issued version.
When construction drawings are revised after their initial issue, the design team must communicate exactly what has changed. A revision cloud is the standard graphic convention for this purpose. It consists of a series of connected arcs forming an irregular cloud shape that encircles the modified area. Each revision cloud is labeled with a revision number or letter that corresponds to an entry in the revision block of the title block.
Revision clouds serve a dual purpose: they draw attention to the changed area, and they help reviewers distinguish new changes from previous revisions. When a sheet has been revised multiple times, each set of clouds carries a different revision number, creating a visual history of changes over time. Previous revision clouds are typically shown lighter or dashed to distinguish them from the current revision.
Proper use of revision clouds is an important professional practice. Clouds should tightly surround the changed area without being so large that they encompass unchanged elements. Each cloud must have a corresponding entry in the title block revision schedule that describes the nature of the change. Missing or inaccurate revision clouds can lead to field errors when contractors fail to notice a critical change.
Why It Matters
Revision clouds prevent the dangerous situation where a contractor builds from an updated drawing without realizing something has changed. On a project with hundreds of sheets, it is impractical for field crews to compare every detail of every new sheet against the previous version. Revision clouds direct attention to exactly where changes occurred, reducing the risk of missed modifications.
How HomeFloorPlan Helps
HomeFloorPlan makes revision tracking automatic and visual. When a revised sheet is uploaded, the platform highlights the new version and maintains the previous version for comparison. Teams can view sheets side by side or overlaid to see exactly what changed, supplementing the architect revision clouds with digital comparison tools.
Frequently Asked Questions
What does a revision cloud look like on construction drawings?
A revision cloud is a series of connected arcs that form an irregular cloud-like boundary around the area of the drawing that has been modified. It is typically drawn with a heavier line weight than the drawing content and is labeled with a revision number or letter.
Are revision clouds required on construction drawings?
While not technically required by code, revision clouds are a universal industry standard and professional best practice. Most contracts and project specifications require that all drawing changes be identified with revision clouds and documented in the title block revision schedule.