Reference
Floor plan symbols, decoded: a reference for designers
A practical reference to the symbols you see on real architectural drawings (walls, doors, fixtures, electrical, dimensions) and what each one means.
Floor plan symbols are the standardized graphical marks architects and engineers use to represent walls, doors, fixtures, electrical, and dimensions on construction drawings. Most of them are codified by the National CAD Standard (currently NCS v6) in the United States and by ISO 7519:1991 internationally. Office variations are common, though, which is why a quick reference matters.
A contractor sends you a PDF of the existing plan before your kickoff meeting. You count five hatch patterns you cannot identify, an arc you think might be a door but the swing is missing, and a circle with a triangle inside it next to the stove. The set has no legend. This reference covers the floor plan symbols you will actually see on architectural drawings: what each one means, why it is drawn that way, and where the conventions come from.
Where floor plan symbols come from
Floor plan symbols go by a few names: architectural symbols, blueprint symbols, or the floor plan legend when grouped on the title sheet. Two standards bodies define most of what you see. The National CAD Standard, published by the National Institute of Building Sciences, is the closest thing to an industry-wide convention in the United States. Internationally, ISO 7519:1991 governs graphical symbols for technical construction drawings. Both define a baseline, but most firms layer in their own office standards on top, which is why two architects in the same city can draw the same window three different ways.
When in doubt, look for the floor plan legend, usually on the first sheet of the set. If there is no legend (the case for most listing PDFs and older drawings), work from the conventions below.
Walls and structural elements
Walls are the heaviest lines on a plan. Their thickness and hatch tell you what they are made of.
| Symbol | Meaning |
|---|---|
| Two parallel lines, solid fill | Existing wall (poché) |
| Two parallel lines, no fill | New wall in a renovation |
| Diagonal hatch between two lines | Concrete masonry unit (CMU) |
| Dotted parallel lines | Demolished wall (to be removed) |
| Dashed line | Hidden element above (soffit, beam, upper cabinet) |
| Heavy chain-dotted line | Property line |
| Thin chain-dotted line | Centerline of a wall, column, or grid |
Column grids appear as circles with letters or numbers at the intersection of two chain-dotted lines. Structural columns themselves are usually drawn as filled squares, rectangles, or circles, depending on whether they are steel, concrete, or wood.
Read the wall hatch before anything else. It tells you what you can move (stud wall), what is structural (CMU, concrete), and what is staying (poché).
Doors
Door symbols carry more information per square inch than almost anything else on a plan.
| Symbol | Meaning |
|---|---|
| Quarter-circle arc with a line at one end | Hinged door: arc shows the swing direction |
| Two arcs meeting in the middle | Double door |
| Solid bar with arrows | Sliding door |
| Two thin parallel lines crossing the wall opening | Pocket door |
| Three offset rectangles in the opening | Bi-fold door |
| Circle in the swing arc | Door tag, keyed to the door schedule |
The swing tells you which way the door opens and which side the hinges live on. If you are planning furniture, the swing arc is the floor area you cannot use.
A door with no swing drawn, just a gap in the wall, is a cased opening. No door installed.
Windows
Windows show up as three parallel lines breaking the wall.
| Symbol | Meaning |
|---|---|
| Three parallel lines across the wall | Standard window |
| Window with a triangle pointing toward the hinge | Casement |
| Diagonal lines inside the window | Awning (top hinge) or hopper (bottom hinge) |
| Heavy line outside the wall with sill mark | Bay or bow window |
| Window with a "T" mark | Tempered glass: required near doors, tubs, low sills |
Sill heights are usually noted next to the window as "SH 30": the bottom of the glass sits 30 inches above the finished floor.
Stairs and level changes
| Symbol | Meaning |
|---|---|
| Series of parallel lines with an arrow | Stair: arrow always points up |
| "UP" or "DN" with a number | Direction and tread count |
| Diagonal break line across the stair | Stair continues to the next floor |
| Dashed outline above an opening | Ceiling change or skylight above |
| Hatched triangle | Ramp: hatch indicates slope direction |
The arrow always points in the up direction, even on the floor above. This trips up a lot of people: the same stair on the second-floor plan still has the arrow pointing up to floor three, not back down to floor one.
Plumbing fixtures
Plumbing symbols are mostly literal. They look like a small plan view of the fixture.
| Symbol | Meaning |
|---|---|
| Rectangle with one rounded corner | Bathtub: rounded corner is the head end |
| Square or circle | Shower (square = stall, circle = drain) |
| Oval inside a rectangle | Sink: oval is the basin |
| Two ovals in one rectangle | Double-bowl sink |
| Rounded rectangle with a circle at one end | Toilet: circle is the bowl |
| Rectangle with "W" or "D" | Washer or dryer |
| Circle with "FD" | Floor drain |
| Hexagon with "WH" | Water heater |
Sinks and tubs are usually drawn to scale. Measure them on the PDF and you will get close to the real size. Toilets vary; the symbol is more diagrammatic than dimensional.
If you are working from a PDF that has these symbols but you need them as editable CAD geometry, whether for a remodel quote, a furniture layout, or a permit application, Plana vectorizes floor plan PDFs into clean, layered DWG and SVG files, with walls, openings, and fixtures on the layers you expect.
Electrical and lighting
Electrical symbols are some of the most standardized, since most come straight from the NCS, but they are also the most cryptic until you have seen a few sets.
| Symbol | Meaning |
|---|---|
| Circle with a line through it | Ceiling-mounted light fixture |
| Circle with arrows | Recessed downlight ("can light") |
| Circle with "WP" | Wall-mounted light |
| Triangle | Junction box |
| Two parallel lines with one short crossbar | Single-pole switch |
| Same with "3" | Three-way switch: paired with another |
| Circle with two short parallel lines | Duplex outlet |
| Outlet with "GFI" or "GFCI" | Ground-fault outlet: required near water |
| Outlet with "WP" | Weatherproof outlet: exterior use |
| Square with "T" | Thermostat |
| Square with speaker icon | Smoke detector or low-voltage device |
Dashed lines connecting a switch to a fixture show what the switch controls. This is the one place where dashed lines are not always "above"; they are a wiring diagram convention.
Appliances and built-ins
| Symbol | Meaning |
|---|---|
| Rectangle with "REF" | Refrigerator |
| Square with four circles | Cooktop or range |
| Rectangle with circle plus triangle | Range with downdraft vent: triangle points to the vent |
| Square with "DW" | Dishwasher |
| Rectangle with "MW" overhead | Microwave, often dashed because it is mounted above |
| Circle with "G" near a range or cooktop | Gas stub-out |
| Two parallel lines above a cabinet | Upper cabinet: dashed because it is above the cut plane |
Per the National CAD Standard, the cut plane on a floor plan is conventionally four feet above the finished floor. Anything below is drawn solid; anything above is drawn dashed. Upper cabinets, soffits, beams, and ceiling fixtures all show up as dashed for this reason.
When you need ceiling-level information such as height, soffit profile, or can-light layout, cross-reference the reflected ceiling plan (RCP), usually sheet A2.1 or A2.2.
Furniture and FF&E
Presentation plans often include furniture, fixtures, and equipment (FF&E) drawn in for scale and layout review.
| Symbol | Meaning |
|---|---|
| Rectangle with three or four cushion divisions | Sofa or sectional |
| Rounded square with smaller square inside | Lounge chair |
| Rectangle with rounded ends and pillows at one end | Bed: size usually noted (K, Q, F, T) |
| Round or rectangular outline with chairs around it | Dining table: chair count drawn |
| Rectangle near a wall with shelf hatching | Casegoods (dresser, console, credenza) |
If furniture appears on an architectural sheet (A-series), it is usually a scale reference, not a specification. Confirm anything you plan to design or build around.
HVAC and mechanical
You will see these on mechanical sheets more than on architectural sheets, but they often appear on combined sets.
| Symbol | Meaning |
|---|---|
| Square or rectangle with diagonal lines | Supply air register |
| Rectangle with grille pattern | Return air grille |
| Circle with fan blades | Ceiling fan |
| Square with "RA" or "SA" | Return air or supply air duct |
| Dotted rectangle in the ceiling | Access panel |
Dimensions, annotations, and callouts
These are not fixtures, but they are the symbols that tell you everything else about the drawing.
| Symbol | Meaning |
|---|---|
| Number between two arrows or ticks | Dimension, in feet-inches or millimeters |
| Letter in a circle | Room tag, keyed to the room schedule |
| Number in a hexagon | Detail callout, points to a detail sheet |
| Letter on a dashed line through the plan | Section cut: letters match the section sheet |
| Arrow with a number | Elevation marker: number is the sheet, letter is the elevation |
| Small filled triangle | North arrow |
| "+/-" before a number | Verify in field |
| Number inside a cloud outline | Revision: the cloud encloses what changed |
Revision clouds are the single most useful annotation when you are picking up a project mid-design. They tell you what changed since the last set was issued, and which discipline made the change.
What to do when symbols don't match anything in this reference
Three options, in order of speed:
-
Check the legend
Even a sparse legend on sheet A0.0 usually catches the unusual symbols.
-
Check the consultant's sheets
MEP and structural disciplines define their own symbols. The plumbing mark you cannot identify on A2.0 is probably explained on P1.0.
-
Ask the architect of record
Office-specific conventions are not in any public standard. A two-minute email beats an hour of guessing.
If the drawing is from another era (pre-1990s sets often used different conventions), cross-reference with a vintage architectural standards guide. The basic geometry has not changed, but symbols for things like cable, data, and ventilation have shifted.
Frequently asked questions
What is the cut plane on a floor plan?
The horizontal plane, conventionally four feet above the finished floor, that defines what is drawn solid (below the plane) and what is drawn dashed (above). It is why upper cabinets, beams, and ceiling fixtures appear as dashed lines.
Why are some walls filled and others hollow?
Filled walls (poché) are existing construction. Hollow walls, just two parallel lines, are new construction in a renovation drawing. Dotted parallel lines are walls being demolished.
What does a number in a hexagon mean?
It is a detail callout. The number points to a detail elsewhere in the set, usually on a sheet starting with "A5" or "A6," showing how that piece of construction is built.
Are floor plan symbols the same internationally?
Mostly, but not exactly. ISO 7519 covers core conventions used in Europe and most of the world. The National CAD Standard governs the United States. Door swings, dimension formatting, and electrical symbols differ the most.
How do I know if a wall is load-bearing from a floor plan?
You usually cannot, at least not from the plan alone. Heavy wall hatches and walls that align across floors are clues. The definitive answer is on the structural drawings (S-sheets) or in a field investigation.
Turn that PDF into editable CAD
If you need the symbols above as real layered geometry, whether for a furniture plan, a remodel quote, or a permit set, Plana vectorizes the PDF and hands you a clean DWG.
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