Floor plan symbols are the graphic shorthand for walls, doors, windows, stairs, fixtures and other building elements on a plan. They follow one logic: a floor plan is a horizontal cut through the building, typically about 4 feet (1.2 m) above the floor, seen from above. Whatever the cut passes through (walls, columns) is drawn with the heaviest lines; what lies below the cut is drawn with thinner lines; what is above it (beams, upper cabinets, skylights) is drawn dashed. Exact symbols vary between offices, so the legend on the drawing set always governs, but once you know the logic, almost any plan becomes readable.
Are floor plan symbols standardised?
Partly. In the US, the National CAD Standard's Uniform Drawing System includes a symbols module, organised by CSI MasterFormat division. Internationally, ISO 7519 sets general principles for presenting building drawings. In practice every office adapts symbols, and each drawing set defines its own on a legend or symbols sheet, usually at the front of the set (in US sets, a G-series or A-0 sheet). When a symbol on a plan is unclear, the legend is the answer, not a generic chart. For reference symbols such as section markers, detail callouts and door tags, see our guide to architectural drawing symbols.
Lines: cut, below and above
| Line | Usually means |
|---|---|
| Heavy solid line | Cut elements: walls, columns, structure. Columbia University's CAD standard, for example, sets cut lines at 0.40 mm or more. |
| Thin solid line | Elements seen below the cut: doors, furniture, cabinets, windows, counters (the same standard uses 0.20 to 0.25 mm for these, and about 0.10 mm for door swings) |
| Dashed line | Elements above the cut (upper cabinets, beams, soffits, skylights, roof edge) or hidden below the floor. The legend says which. |
| Long dash, short dash | Centre lines and grid lines |
Many sets also fill (poché) the walls, often differently for existing and new walls, and give each wall type a tag or hatch defined in the legend or on a partition types sheet.
Walls and fire-rated walls
A wall is drawn as two heavy lines at its full thickness, with or without a fill. There is no universal symbol for fire-rated walls: some legends use a different linetype or hatch per rating (1 hour, 2 hours), others add a tag referring to the rated assembly. The Joint Commission, which accredits US healthcare buildings, requires their life safety drawings to show all fire-rated and smoke-rated barriers; a legend explaining how each rating is marked is good practice for any set. Read the fire rating from the legend, not from the line weight.
Doors
- Swing door: a line for the door leaf, drawn open (often at 90°), and a thin arc showing the swing. The arc tells you which way the door opens and which side the hinges are on.
- Double door: two leaves and two arcs meeting in the middle.
- Sliding and pocket doors: the leaf drawn parallel to the wall, beside the opening (sliding) or inside the wall (pocket), usually with no arc.
- Bi-fold doors: leaves drawn as a zigzag in the opening.
- Door tags (a number in a shape) point to the door schedule, which gives size, material, fire rating and hardware.
Windows
A window is a break in the wall with thin lines for the glass and the sill, usually two or three parallel lines across the wall thickness. Casement windows may show a swing arc like a door. Window tags point to the window schedule, which gives sizes and types; the plan itself rarely carries the full window size.
Stairs, ramps and elevators
- Stairs are drawn as a series of treads cut by a diagonal break line, which marks the plan's cut plane: below it you see the treads, above it the continuation may be dashed or omitted. An arrow along the stair runs from the floor shown, labelled UP or DN. Many offices add the riser count (for example "17R UP"), but that notation is a convention, not a standard.
- Ramps show an arrow in the direction of travel, usually with the slope written on it.
- Elevators and shafts are commonly drawn as a rectangle with a cross; an X across an area also commonly marks an opening or "open to below". Check the legend: the same X can mean different things in different sets.
Plumbing fixtures and kitchens
Toilets, washbasins, sinks, showers, tubs and floor drains are drawn as simplified outlines of the fixture as seen from above: an oval bowl and a tank for a toilet, a rectangle with a drain for a shower, a small circle with a cross or hatch for a floor drain. Kitchen appliances are drawn as rectangles with a label (REF, DW, RANGE). Fixtures carry tags or appear in a plumbing fixture schedule on the engineer's drawings; see how to read MEP drawings.
Dimensions
Dimension strings run along the outside of the plan, usually in three tiers: overall, wall to wall, and openings. What a dimension is measured to matters as much as the number. The AIA's best-practice guidance on dimensioning recommends dimensioning to the face of the gypsum board, masonry or concrete in most cases, and to the face of finish where a clear width matters, such as egress routes and accessible toilet rooms. Openings are often dimensioned to their centre line. A general note in the set should say which convention applies; if it does not, ask.
Rooms, areas and heights
Room names and numbers sit inside each room, often with the floor area, the floor finish code or the ceiling height. Room numbers link the plan to the finish schedule and to the room data in other disciplines' drawings.
Accessibility clearances
Accessible rooms often show the required wheelchair turning space as a dashed circle. Under the US 2010 ADA Standards (section 304.3) the turning circle is at least 60 inches (1525 mm) in diameter, or a T-shaped space may be used instead. In England, Approved Document M asks for a 1500 mm circle in the bathrooms of wheelchair user dwellings (category M4(3)). Other codes and editions differ, so the label on the circle should state the size.
How to read a floor plan, step by step
- Read the title block, the scale and the north arrow.
- Find the legend and the general notes, especially what dimensions are measured to.
- Read the structure first: the grid and the columns.
- Follow the walls, telling cut walls from lower elements by line weight.
- Read the openings: doors (which way they swing) and windows, with their tags.
- Walk through the rooms in your mind, from the entrance, reading names, numbers and fixtures.
- Look for dashed lines and ask what is above or below.
- Follow every tag and callout to its schedule, detail or section.
Frequently asked questions
What do dashed lines mean on a floor plan?
Usually something above the cut plane (upper cabinets, beams, soffits, skylights) or hidden below the floor. The legend says which.
What does an X mean on a floor plan?
Commonly an elevator shaft, a vertical shaft or an opening to the floor below. The legend of the set confirms it.
What is the door symbol on a floor plan?
A line for the door leaf drawn open and a thin arc showing the swing, so you can see which way it opens.
How do you read floor plan dimensions?
Read the dimension strings from the outside in (overall, wall to wall, openings), and check the general notes for what each dimension is measured to: face of wall, face of finish or centre line.
Are floor plan symbols the same everywhere?
No. There are standards and common conventions, but each drawing set defines its symbols in its own legend, and that legend governs.
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 plans stay smooth to zoom into a door swing or a fixture and to pan across a floor. Measure to scale (metric units), mark a question with a revision cloud and a comment, and compare two issues of a plan as a colour overlay to see what moved. 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: architectural drawing symbols, how to read construction drawings, north arrow on drawings.
All product names, standards and organisations mentioned on this page are trademarks or registered names of their respective owners and are used for identification only. Ncored is an independent product by Noir architects and is not affiliated with, sponsored by, or endorsed by any of them. This page explains common drawing conventions; each project's legend, notes and adopted codes govern. Individual experiences may vary.