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Reading a Floor Plan

Floor Plan Symbols Explained

A visual reference to the symbols used on architectural floor plans and room layouts — doors, windows, walls, stairs, bathroom and kitchen fixtures, electrical fittings and the annotation that ties a drawing set together.

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How to read a floor plan

A floor plan is a horizontal slice through a building, taken about a metre (roughly 4 ft) above the floor and looked at from above.

  • Anything the slice cuts through — walls, columns, door and window openings — is drawn with a heavy line.

  • Anything below the cut, like a countertop or a bathtub, is drawn lighter.

  • Anything above the cut, like a beam or a wall cabinet, is drawn dashed.

Once you know that, most symbols explain themselves. The rest of this page is the vocabulary: what each mark means, what it is also called, and what it tells you that is easy to miss.

One caveat before you start. There is no single universal symbol set. ISO, the US National CAD Standard and BS 1192 all differ in places, especially over electrical fittings, and individual drawing offices add their own conventions. If the drawing in front of you has a legend, the legend wins — including over this page.

Wall Symbols

Walls are the thickest lines on any plan, and their weight is doing real work: the heavier the line, the more structural the wall. Read the walls first and the rest of the drawing falls into place.

  • Exterior wall

    Also called: load-bearing wall

    Drawn as two parallel lines with the cavity between them hatched or poached solid. It is the thickest line on the plan — typically 200–300 mm (8–12 in) — because it carries the roof and the floors above.

  • Interior partition

    Also called: non-load-bearing wall

    A thinner solid band, usually 90–150 mm (3.5–6 in). Partitions divide rooms but hold nothing up, which is why they are the walls an architect will move first when a layout needs rework.

  • Half wall or low wall

    Also called: pony wall, knee wall

    Shown with a dashed or lighter outline to say the wall does not reach the ceiling. Common between a kitchen and a dining area, or as a stair balustrade.

  • Column or post

    Also called: pier

    A small solid square or circle standing free of the walls. It marks a point load — a beam lands here — so it is one of the few things on a plan you genuinely cannot move.

Door Symbols on Floor Plans

The door symbol on a floor plan does two jobs at once: it shows where the opening is and how the door behaves. The arc is the important part — it is the space the leaf sweeps through, and furniture cannot live inside it.

  • Single swing door

    Also called: hinged door

    A straight line for the leaf plus a quarter-circle arc showing the swing. The hinge is at the end the arc starts from, so the symbol also tells you which way the door opens and into which room.

  • Double door

    Also called: French doors

    Two leaves meeting in the middle, each with its own arc. Usually 1.5–1.8 m (5–6 ft) wide overall — worth checking, because a double opening eats a lot of wall.

  • Sliding door

    Also called: patio door, slider

    Two overlapping bars drawn on slightly offset lines, with no arc — a slider sweeps no floor area, which is exactly why it turns up in tight rooms and onto balconies.

  • Pocket door

    Like a slider, but the leaf disappears into a dashed cavity inside the wall. The dashed box is the pocket, and it means that stretch of wall cannot hold a switch, a socket or a picture hook.

  • Bifold door

    Also called: folding door

    A zigzag of short segments, because the leaves fold against each other. Standard on wardrobes and laundry cupboards where a full swing would not fit.

  • Garage door

    Also called: overhead door

    A wide opening spanned by two or three light parallel lines representing the panels. It is drawn flat because a sectional door travels up rather than across the floor.

Window Symbols on Floor Plans

Windows sit inside the wall rather than breaking it, so the wall hatching stops and thin lines take over. The number of lines and whether there is an arc tells you the window type.

  • Fixed window

    Also called: picture window

    Three thin parallel lines across the opening: the two wall faces and the glass between them. No arc means no opening light — it is glass you cannot open.

  • Casement window

    Also called: awning window in plan

    The same thin lines plus a swing arc, drawn just like a door. The arc shows the side the sash is hinged on and how far it projects when open.

  • Sliding window

    Also called: sash window

    Two offset bars within the opening, mirroring the sliding-door symbol. A sash window that slides vertically is often drawn the same way, so check the legend or the elevations.

  • Bay or bow window

    The wall steps outward into a trapezoid or a shallow curve. Everything inside the projection counts as extra floor area, which is worth knowing before you total up a room.

Stairs and Level Changes

Stairs are drawn as a run of treads with an arrow, and the arrow is not decorative — it tells you which direction you are travelling from the floor you are currently looking at.

  • Staircase

    Also called: stair run

    A rectangle divided into treads with an arrow marked UP or DN. On a ground-floor plan the same flight appears as UP; on the first-floor plan it appears as DN. Count the treads to work out the rise.

  • Spiral staircase

    Also called: helical stair

    A circle with radial treads around a central newel. Compact in plan, but the narrow inner end of each tread is why spirals are often not allowed as the only route to a bedroom.

  • Ramp

    A rectangle with a long arrow pointing up the slope, sometimes annotated with the gradient. Look for it at entrances and wherever a plan has to deal with a level change without steps.

Bathroom Symbols

Bathroom fixtures are drawn in plan as the shape you would see looking straight down at them, simplified to an outline. They are usually the easiest symbols on a drawing to recognise.

  • Toilet

    Also called: WC, water closet

    A rounded bowl with a rectangular cistern behind it, drawn against the wall the soil pipe runs down. Allow roughly 700–800 mm (28–32 in) of clear space in front of it.

  • Basin

    Also called: sink, lavatory, vanity

    A rectangle for the counter with an oval or circle inside for the bowl, plus a short stub for the tap at the back.

  • Bathtub

    Also called: bath

    A rounded rectangle with an inner outline for the tub itself and a small circle at the drain end. A standard tub is about 1,700 × 700 mm (5 ft 6 in × 2 ft 6 in).

  • Shower

    Also called: shower tray, shower enclosure

    A square or rectangle crossed by two diagonals, with the drain marked where they meet. The diagonals are the convention that separates a shower from a plain tiled area.

Kitchen Symbols

Kitchen appliances are drawn at their real footprint, which is what makes a kitchen plan useful: if the symbols fit on the drawing at scale, the appliances fit in the room.

  • Kitchen sink

    A rectangle set into the worktop, divided into one or two bowls, with a tap stub at the back. A double bowl is usually 800–900 mm (32–36 in) wide.

  • Cooktop or range

    Also called: hob, stove

    A square with four circles for the burners or zones. Six circles means a wider range; a dashed rectangle above it usually indicates the extractor hood.

  • Refrigerator

    Also called: fridge, REF

    A rectangle with a horizontal division for the freezer compartment and short marks for the door handles, often labelled REF or F. Leave the door swing clear on the handle side.

Electrical Symbols

Electrical symbols sit on a separate layer from the architecture and are drawn much lighter. On a full drawing set they often get a sheet of their own — an electrical plan — rather than crowding the floor plan.

  • Power outlet

    Also called: socket, receptacle, duplex outlet

    A half-circle sitting on the wall line with two short ticks for the sockets. Drawn on the wall it serves; a circle with four ticks is a double, and a variant with GFCI or RCD written beside it is the protected type for wet areas.

  • Light switch

    Also called: wall switch

    An S beside a short bar on the wall. A curved dashed line from the switch to a fitting shows what it controls; S3 (or 2-way) means the fitting is switched from two places.

  • Ceiling light

    Also called: luminaire, light fixture

    A circle with rays. Recessed downlights are usually plain small circles in a grid, and a rectangle with a cross is normally a fluorescent or linear fitting.

  • Ceiling fan

    A hub with four blades sweeping around it. Where the fan also carries a light, the symbol is drawn over a light circle.

  • Smoke detector

    Also called: SD, smoke alarm

    A circle marked SD, placed on the ceiling. Their positions are set by code rather than by preference, so they are one of the few electrical symbols you should not move on a whim.

Annotation and Reference Symbols

These are the marks that make a plan readable rather than the things being built. They tell you how big something is, which way is north, and where to look for the rest of the drawing set.

  • Dimension line

    A line running between two extension lines, terminated with arrows or slashes, with the measurement written on or above it. Dimensions are almost always taken to the face of the structure, not to the finished surface.

  • North arrow

    An arrow marked N, usually in a corner of the sheet. It is what turns a layout into a real building on a real site — it tells you which rooms get the morning sun.

  • Section or elevation marker

    Also called: section cut, callout

    A circle with a letter and a tail pointing in a direction. The letter identifies a drawing elsewhere in the set; the tail shows which way that drawing looks.

  • Room name and area

    The room name with its floor area beneath, inside a dashed boundary where the extent is ambiguous. Check whether the area is measured to the inside face of the walls or includes them — the two differ by several percent.

Common questions about floor plan symbols

They are a shorthand drawing language for a building seen from above. Instead of drawing a door in perspective, a plan uses a line and an arc that say "door here, hinged on this side, swinging this way". The same applies to windows, stairs, fixtures and electrical fittings, so a plan can carry a great deal of information in very little ink.

No. There are national and international standards — ISO 4157 and ISO 7519, the US National CAD Standard, BS 1192 in the UK — and they agree on most of the common symbols but differ in the details, particularly for electrical work. Individual drawing offices then add house conventions on top. The legend printed on the drawing you are holding always takes precedence over any general guide, including this one.

Most commonly as a gap in the wall with a straight line for the door leaf and a quarter-circle arc for its swing. Sliding doors drop the arc and show two offset bars, pocket doors add a dashed cavity inside the wall, and bifold doors are drawn as a zigzag. Offices vary, so check the legend if a mark looks unfamiliar.

It is the path the door leaf sweeps as it opens. It tells you which side the hinges are on, which way the door opens, and how much floor has to stay clear. If you are placing furniture, treat everything inside the arc as unusable.

Usually three thin parallel lines set within the wall thickness: the two wall faces and the glass between them. The opening type adds to that — a casement window gets a swing arc, a sliding window gets two offset bars, and a bay window steps the wall outward. A given drawing office may use a variant, and its legend takes precedence.

A window is drawn as thin parallel lines within the thickness of the wall and the wall carries straight through the opening. A door leaves a gap in the wall with a leaf line and, unless it slides, an arc. A casement window does have an arc, but it sits inside the wall thickness rather than breaking it.

It is the direction of travel from the floor you are currently looking at. The same flight of stairs reads UP on the lower floor plan and DN on the upper one, which is a useful check that you are looking at the storey you think you are.

Line weight indicates structure. Thick, hatched walls are external or load-bearing and hold the building up. Thinner solid walls are partitions that only divide space. Dashed or lighter outlines usually mean the element does not reach the ceiling, or sits above the cut plane — a beam or an overhead cupboard, for instance.

Usually something above the cut plane, such as wall cabinets, a beam or an extractor hood, or something that does not reach the ceiling, like a half wall. Dashed lines also mark the cavity of a pocket door and room boundaries where the extent is ambiguous. The meaning is a convention rather than a rule, so the legend on the drawing has the final word.

Residential plans are commonly 1:50 or 1:100 in metric, and 1/4 in = 1 ft or 1/8 in = 1 ft in imperial. The scale is printed near the title block, and it is what lets you measure a wall on the drawing and convert it to a real dimension — though written dimensions should always be trusted over measured ones.

For a sketch you are only showing to yourself, no. As soon as someone else has to read it — a builder, a landlord, a planning officer, a kitchen supplier — using the conventional symbols saves a conversation, because they already know the language.

Turn a room list into a labelled floor plan image

Describe the rooms and generate a 2D plan image with walls, doors and windows marked. Measurements in the image are approximate — it is a planning aid, not a permit-ready drawing.

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