A key plan is a small, simplified plan of the whole building printed on a drawing sheet, usually in or next to the title block, with the part shown on that sheet shaded or hatched. It tells the reader where the enlarged area in front of them sits within the building. Key plans are used when a building is too large to show at a readable scale on one sheet, so the plan is split across several sheets joined by match lines, and in renovation projects to show the area of work. Some owners require them: the US General Services Administration's CAD standard lists "Key plan and North arrow" among the minimum title block contents, where applicable.
What a key plan shows
- The outline of the whole building (or of the whole campus, for a group of buildings), drawn at a small scale.
- The area shown on this sheet, shaded or crosshatched. Eastern Kentucky University's drawing standard, for example, says key plans "shall indicate represented plan area by crosshatching".
- Match lines and the other areas, often labelled with their sheet numbers or area letters (Area A, Area B).
- A north arrow, pointing the same way as on the plans. The University of Michigan's design guideline asks for the same orientation on all plan sheets.
- Sometimes grid lines, phases, and for renovations the nearest street and the contractor's access (the University of Pittsburgh's design manual asks for both).
Where it goes on the sheet
There is no single international rule. Owners and agencies set it in their CAD standards: the GSA includes the key plan in the title block, the University of Michigan asks for it "in the lower right portion of the drawing area", and many offices place it just above the title block. The international title block standard ISO 7200 does not include a key plan field at all: it covers document management data such as the owner, the identification number and the approval. If your client has a CAD standard, it decides; otherwise keep the key plan in the same place on every sheet.
When a key plan is needed
- Large buildings split across sheets. When a floor plan would be unreadable on one sheet at the required scale, it is divided into parts with match lines. Eastern Kentucky University's standard then requires the whole plan at a smaller scale and "appropriate key plans and match lines" on the segmented drawings.
- Campuses and groups of buildings, to show which building a sheet belongs to.
- Renovations and fit-outs in existing buildings, to show the area of work.
- Enlarged plans (toilets, stairs, kitchens), to show where the enlargement sits.
Key plan, location plan, site plan and vicinity map
| Drawing | Answers | Typical scale |
|---|---|---|
| Key plan | Where is this sheet's area within the building? | Very small, often not to a stated scale |
| Site plan (block plan) | How does the building sit on its plot? | 1:200 or 1:500 in planning practice in England and Wales |
| Location plan | Where is the site in its area? (planning in England and Wales: site edged in red, other land owned in blue) | 1:1250 or 1:2500 in planning practice in England and Wales |
| Vicinity map | Where is the site relative to roads and landmarks? (common on US cover sheets) | Small |
In civil engineering the term is used for the larger picture too: the City of Nanaimo's engineering standards, for example, ask for a "Key Plan to a small scale (e.g., 1:10,000)" showing the works in relation to major streets. Read the word in the context of the set.
For what a site plan must show and how to read bearings, setbacks and contours, see site plan: what it shows and how to read one.
How to read a key plan
- Find the shaded or hatched area: that is the part of the building on this sheet.
- Read the match lines on the plan itself, and the sheet references next to them, to find the neighbouring parts.
- Check that the north arrow on the key plan points the same way as the plan's north arrow.
- Use the grid lines to check that the shaded area matches the grids actually shown on the sheet.
- On renovations, note the area of work, the access route and any phasing marked.
How to make a key plan
Revit
Revit has no dedicated key plan tool, but it has the pieces that splitting a plan needs. Create the parts with View tab, Create panel, Duplicate View, Duplicate as Dependent (dependent views stay in sync with the main view, and each can have its own Scope Box). Draw match lines with View tab, Sheet Composition panel, Matchline, then Finish Matchline, and add view references. For the key plan itself, offices commonly place a small-scale plan view on each sheet with the area highlighted, or build filled regions into the title block family and switch them on per sheet with yes/no parameters. A model view cannot be placed inside a title block family.
ArchiCAD
ArchiCAD has no key plan command either. A common approach is a saved view of the whole floor with its own layer combination and pen set, placed on each layout at a small scale and cropped, with the area highlighted. Items that should appear on every sheet can sit on the Master Layout.
AutoCAD
Typical practice is a small paper-space viewport or a block of the building outline with a hatch per area, placed in or beside the title block. Your office standard usually defines it.
Common mistakes
- The shading was not updated after the plan was split differently, so the key plan points to the wrong area.
- Copies of the key plan drift apart between sheets (one copy updated, others not).
- The north arrow on the key plan points a different way from the plans.
- A key plan copied from an old DWG no longer matches the current building outline.
Frequently asked questions
What is a key plan in architecture?
A small plan of the whole building on a drawing sheet, with the area shown on that sheet shaded, so the reader knows where the sheet fits.
Where is the key plan on a drawing?
Usually in or next to the title block, or in the lower right of the drawing area. The client's or office's CAD standard decides.
What is the difference between a key plan and a site plan?
A key plan locates a sheet within the building. A site plan shows the building on its plot, with boundaries, access and external works.
Is a key plan required?
Not by a single international rule, but many owners require one (the US GSA lists it among the minimum title block contents where applicable), and it is standard practice whenever a plan is split across sheets.
What is a match line?
The line where one part of a split plan continues on another sheet, labelled with the sheet that shows the continuation.
Ncored is the desktop PDF editor we built in our architecture studio for drawing sets from AutoCAD, Revit, and ArchiCAD, on Windows and Mac (Apple Silicon). Large sets stay smooth to zoom and to move between sheets, so you can follow a match line to the next sheet and back. Mark a key plan that no longer matches with a revision cloud and a comment; markups are saved as standard PDF annotations that open in Acrobat, Bluebeam, Preview and other standard PDF viewers. 14 days free. No signup, no email, nothing to enter.
Related: the title block, north arrow on drawings, architectural sheet numbering.
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