What Is an Enlarged Plan?

On the floor plan, a boundary encloses the area with a tag giving the drawing number over the sheet number, such as 3 over A-401. The enlarged plan carries the matching title and scale, and its extent should match the callout boundary.

In AutoCAD, the enlarged plan is often a second paper space viewport on the same model space geometry at a larger scale, with annotative dimensions and text set to display only at that scale. Drawn that way, a wall moved on the floor plan moves on the enlarged plan too, because both views show the same objects.

A frequent enlarged plan error is the same information stated on both drawings with different values. A restroom dimensioned on the floor plan and on the enlarged plan drifts apart after the first revision, so good practice is to note see enlarged plan on the floor plan and dimension only on the enlarged plan.

Room numbers, door tags, and fixture tags can appear on both, but dimensions, mounting heights, and accessories belong in one place. A plans examiner who finds two different stall widths will comment on both sheets.

The ADA 2010 Standards set the clearances an enlarged restroom plan has to show: a 60 inch diameter or T-shaped turning space under Section 304, a water closet centerline 16 to 18 inches from the side wall under Section 604.2, and clearance around the water closet of at least 60 inches from the side wall and 56 inches from the rear wall under Section 604.3.

Grab bars under Section 604.5, at least 42 inches long on the side wall and 36 inches on the rear wall, lavatory knee and toe clearance, and door maneuvering clearances under Section 404 are dimensioned on the plan and coordinated with the interior elevations. A door that swings into the clear floor space of a fixture is a frequent plan check comment.

Enlarged stair plans show each flight, landings, riser count, tread depth, clear width, and handrail extensions. IBC Section 1011.5.2 limits risers to 7 inches maximum and treads to 11 inches minimum for most stairs, and the handrail extensions required by Section 1014.6 have to fit within the enclosure.

Enlarged elevator plans coordinate the hoistway size with the manufacturer, the pit depth with the foundation plan, and the machine room or control space with the electrical and mechanical drawings.

Mechanical rooms, electrical rooms, and toilet room plumbing are crowded at 1/8 inch scale, so engineers enlarge them to show equipment, housekeeping pads, piping, and service clearances. The working space NEC 110.26 requires in front of panels and switchboards, 3 feet or more depending on voltage and what faces the equipment, is dimensioned on the enlarged electrical room plan.

Enlarged plumbing plans of restrooms show waste, vent, and supply connections at each fixture and the chase or carrier dimensions, and those have to agree with the architectural enlarged plan of the same room.