Drawing Symbols Guide
165 symbols used on construction drawings — organized by discipline. Material hatches, door and window symbols, structural notation, electrical, plumbing, HVAC, fire alarm, and annotation conventions.
Material Symbols — Plan and Section
Hatch patterns used in plan views and building sections to indicate construction materials. These fill the outline of a shape on the drawing to show what the element is made of.
Earth / Soil
Random dots with short irregular marks
Represents compacted or undisturbed earth in section views. Used on foundation details and site sections.
Rock
Irregular angular shapes tightly packed
Indicates bedrock or large aggregate in geotechnical and foundation sections.
Concrete
Small dots and triangles scattered randomly
The most common structural material symbol. Dots represent the sand and aggregate in the mix.
Structural Concrete
Dots with diagonal crosshatching
Distinguishes reinforced structural concrete from lightweight or non-structural concrete.
Lightweight Concrete
Sparse scattered dots
Used for lightweight concrete fill, often seen on roof deck or floor levelling details.
Concrete Block (CMU)
Diagonal lines with dots between
Represents concrete masonry units. The diagonal lines show the block face; dots indicate the grout-filled cores.
Steel / Iron
Solid black fill or dense diagonal crosshatch
Solid fill for small sections (bolts, small plates). Crosshatch for larger steel members in section.
Aluminium
Alternating thin diagonal lines
Used for aluminium framing, curtain wall mullions, and storefront sections.
Brick
Diagonal lines at 45° running in one direction
Repeating 45° lines represent brick masonry. One of the most recognisable material symbols.
Stone — Cut
Horizontal dashed lines with occasional diagonals
Represents dimensioned or cut natural stone (limestone, granite, marble) in section.
Stone — Rubble
Irregular interlocking shapes
Indicates rough or uncut stone, often seen in retaining wall and foundation sections.
Wood — Framing
Circular rings (end grain) or parallel lines (side grain)
End grain shown as concentric arcs. Side grain shown as parallel wavy lines along the member length.
Plywood
Thin parallel lines alternating direction per layer
Shows the alternating grain layers characteristic of plywood construction.
Glass
Single thin line or solid narrow fill
Represented as a single line in plan, or a narrow solid rectangle in section for plate glass.
Glass Block
Grid of small squares
Shows glass block assemblies in plan and section, common in interior partitions and sidelights.
Insulation — Batt
Wavy zigzag lines (like overlapping X shapes)
The classic "X" pattern indicates batt or blanket insulation in wall and roof cavities.
Insulation — Rigid
Stippled or speckled fill
Represents rigid foam board insulation (XPS, EPS, polyiso) in wall, roof, and foundation assemblies.
Gypsum Board
Thin solid fill with face line
Shown as a narrow solid band on wall sections. Often labelled "GWB" or "GYP. BD." with thickness.
Finish Material
Thin line at surface
A very thin fill applied to surfaces to indicate tile, paint, or other finish material over substrate.
Metal Stud Partition
Stud shape with gypsum faces
Shows C-shaped metal studs between layers of gypsum wallboard. Common in commercial interiors.
Fire Brick
Crossed diagonal lines
Used for refractory brick in fireplaces, kilns, and high-temperature applications.
Ceramic Tile
Small squares in grid pattern
Indicates ceramic or porcelain tile on walls and floors in plan and section views.
Sheet Metal
Thin solid dark band
Represents sheet metal flashing, ductwork, or cladding in section drawings.
Material Symbols — Elevation
Patterns used on building elevation drawings to indicate exterior material appearance. More representational than section symbols.
Brick — Running Bond
Alternating offset horizontal rectangles
The standard brick pattern with staggered joints. Most common elevation symbol.
Brick — Stack Bond
Aligned horizontal rectangles
Bricks stacked with joints aligned vertically. Used for accent patterns and modern facades.
Stone — Squared
Rectangular blocks with joints
Cut stone with regular coursing. Used for limestone, granite, and sandstone cladding.
Stone — Rubble
Irregular interlocking shapes
Rough stone with random sizes and mortar joints. Common on retaining walls and foundations.
Concrete / Plaster
Stippled or lightly dotted surface
A light dot pattern indicating exposed concrete, stucco, or plaster finish on elevations.
Shingles
Overlapping scalloped rows
Indicates asphalt, wood, or slate shingles on roof and wall elevations.
Glass
Diagonal line from corner
A single diagonal line across the pane indicates glazing on elevation drawings.
Metal Panel
Horizontal or vertical parallel lines
Closely spaced parallel lines indicating metal panel cladding, standing seam, or corrugated metal.
Structural Symbols
Symbols used on structural drawings to represent steel shapes, concrete elements, and connection types.
Wide Flange (W Shape)
I-shaped cross section
The standard I-beam profile. Labelled with designation like "W12x26" (12" depth, 26 lb/ft).
Steel Channel
C-shaped cross section
C-shaped structural member. Designated like "C10x20". Used for lintels, framing, and bracing.
Steel Angle
L-shaped cross section
L-shaped member used for lintels, shelf angles, and connections. Designated by leg sizes and thickness.
Steel Tube / HSS
Rectangular or circular hollow section
Hollow structural sections shown as rectangles or circles with wall thickness. Labelled "HSS 6x4x3/8".
Steel Plate
Solid rectangle
A flat steel plate shown as a solid filled rectangle in section. Labelled "PL 1/2" x 8".
Reinforcing Bar
Solid dot (section) or dashed line (plan)
Rebar shown as solid circles in section and dashed lines in plan. Labelled by bar size (#4, #5, etc.).
Welded Wire Mesh
Grid of thin lines
Reinforcing mesh in concrete slabs, shown as a fine grid pattern in section.
Wood Stud
Rectangle with X through it
Cross-hatched rectangle indicating a wood framing member in section.
Column Grid Line
Circle with number or letter at end of line
Grid lines establish the structural layout. Numbers run one direction, letters the other.
Moment Connection
Solid triangle at beam-column intersection
Indicates a rigid (moment-resisting) connection between beam and column.
Shear Connection
Single line at beam-column intersection
Indicates a simple (pin/shear) connection that transfers vertical loads only.
Door Symbols
Plan-view symbols showing door type, swing direction, and operation. The arc indicates the swing path.
Single Door — Opening In
Line with quarter-circle arc swinging inward
The most common door symbol. The arc shows the swing direction and clearance required.
Single Door — Opening Out
Line with quarter-circle arc swinging outward
Door swings away from the viewer. Required for egress doors in many occupancies.
Double Door — Opening In
Two lines with opposing quarter-circle arcs inward
Pair of doors swinging inward. Common at main entries and assembly spaces.
Double Door — Opening Out
Two lines with opposing quarter-circle arcs outward
Pair of outswinging doors. Often required at exits for emergency egress.
Single Door — Interior
Thin line with small arc
Interior passage door. Typically shown with a thinner line weight than exterior doors.
Double-Acting Door
Line with arcs on both sides
Door swings in both directions (like a kitchen service door). Two arcs shown on each side.
Sliding Door
Two parallel lines with arrows
Door slides along a track rather than swinging. Arrows indicate the direction of travel.
Pocket Door
Line sliding into dashed wall cavity
Door retracts into the wall cavity. Dashed lines show the pocket within the wall.
Revolving Door
Circle with X-shaped partitions
Four-wing revolving door shown as a circle with crossed lines at the entry.
Overhead / Roll-Up Door
Dashed line across opening
Used for garage doors and loading docks. Dashed line indicates the door in the open position.
Door Tag
Number in hexagon or rectangle
Identifies the door on the door schedule. Contains the door number (e.g., 109.2).
Window Symbols
Plan-view and elevation symbols showing window type, operation, and configuration.
Double Hung
Two rectangles stacked, arrows up/down
Both sashes slide vertically. The most traditional residential window type.
Single Hung
One rectangle fixed, one with arrow
Lower sash slides up; upper sash is fixed. Common in commercial and residential buildings.
Casement — Single
Rectangle with diagonal line to hinge side
Hinged on one side, swings outward. The diagonal line indicates the hinge point and swing direction.
Casement — Double
Two rectangles with opposing diagonals
Two sashes hinged on opposite sides, both swinging outward.
Awning
Rectangle with diagonal line at top
Hinged at the top, swings outward from the bottom. Allows ventilation during rain.
Hopper
Rectangle with diagonal line at bottom
Hinged at the bottom, tilts inward from the top. Often used in basements.
Sliding
Overlapping rectangles with arrow
One or both sashes slide horizontally on a track.
Fixed
Simple rectangle, no operation indicator
Non-operable window. No arrows, diagonals, or other operation indicators.
Pivot
Rectangle with centre dot
Window pivots on a central axis, either horizontally or vertically.
Window Tag
Number in circle or hexagon
Links the window to the window schedule, which lists type, size, glazing, and hardware.
Reference and Annotation Symbols
Symbols used across all disciplines to reference other drawings, mark locations, and communicate information.
Section Cut
Arrow with line and circle containing sheet number
A line through the plan showing where a building section is taken. The arrow points in the viewing direction.
Detail Callout
Circle with number over sheet number
References a detail drawing. Top number is the detail number, bottom is the sheet where the detail is found.
Elevation Tag
Circle with arrow and number over sheet number
Points toward the face being shown on the referenced elevation drawing.
Wall Type Tag
Rectangle with letters/numbers
Identifies the wall assembly type. Links to the wall type schedule or detail.
Equipment Tag
Circle or hexagon with equipment code
Identifies mechanical, electrical, or plumbing equipment. Links to equipment schedules.
Room Tag
Rectangle or circle with room name and number
Labels each room with its name and number for cross-referencing on finish and door schedules.
Level / Datum
Inverted triangle with elevation number
Indicates a specific elevation (height) relative to the project datum or sea level.
Grid Bubble
Circle at end of grid line with letter or number
Part of the structural column grid system. Numbers typically run east-west, letters north-south.
Revision Cloud
Bumpy cloud outline around changed area
Surrounds areas that have been modified in a revision. Usually accompanied by a revision triangle.
Revision Triangle
Small triangle with revision number
Placed near revision clouds to identify which revision the change belongs to.
North Arrow
Arrow pointing north
Indicates the orientation of the drawing relative to true or project north.
Drawing Scale
Bar scale or text ratio
Indicates the scale relationship between the drawing and actual dimensions (e.g., 1/4" = 1'-0").
Break Line
Zigzag line across element
Indicates that a portion of the drawing has been removed to save space. The element continues beyond the break.
Center Line
Alternating long and short dashes
Indicates the center axis of an element. Used on columns, walls, and symmetrical features.
Hidden / Below Line
Evenly spaced dashes
Represents edges or features hidden behind the cut plane or below the floor in plan view.
Property Line
Long dash, dot, long dash pattern
Indicates the boundary of the property on site plans and civil drawings.
Electrical Symbols
Symbols from NECA 100 and standard practice used on electrical construction drawings for wiring, lighting, power, and systems.
Duplex Receptacle
Circle with two horizontal lines (parallel bars)
Standard 20A/125V duplex outlet. The most common electrical symbol on floor plans.
GFCI Receptacle
Duplex symbol with "GFI" label
Ground fault circuit interrupter outlet. Required in wet locations (kitchens, bathrooms, exterior).
Dedicated / Special Receptacle
Duplex symbol with triangle or number
Outlet for specific equipment. A superscript number references the panel and circuit.
Floor Receptacle
Duplex symbol inside a square
Outlet mounted in the floor. "F" indicates flush mount, "S" indicates surface mount.
Single-Pole Switch
S with subscript
"S" alone for single-pole. "S2" for two locations (3-way), "S3" for three or more (4-way).
3-Way Switch
S₂
Controls a light from two locations. One of the most common switch types in residential and commercial.
Dimmer Switch
S with "DIM" or "D"
Switch with dimming capability. Labelled "SD" or "SDIM" on electrical plans.
Luminaire (General)
Shape drawn to approximate fixture size
Drawn to scale — circles, rectangles, or lines representing the fixture shape and size.
Fluorescent / LED Strip
Narrow rectangle (length to scale)
Linear fixture drawn to scale length. Often with type letter linking to the fixture schedule.
Recessed Downlight
Circle with line through center
Recessed round fixture. A slash through the circle indicates the fixture is recessed.
Exit Light
Circle-arrow with "X" or "EXIT"
Exit sign luminaire. Arrows on the symbol indicate the direction of egress.
Emergency Battery Unit
Triangle with arrow heads
Emergency lighting with integral battery backup. Arrow heads indicate remote lamp locations.
Surface-Mounted Fixture
Fixture shape with no slash
No modifier line through the symbol indicates surface-mounted installation.
Wall-Mounted Fixture
Fixture shape on wall line
Placed directly on the wall line in plan view, with leader if not on wall.
Suspended Fixture
Fixture shape with dot in center
Dot inside the symbol indicates pendant, chain, or cable-hung installation.
Conduit — Concealed
Solid line
Solid line indicates conduit concealed in walls, above ceiling, or below slab.
Conduit — Exposed
Dashed line
Dashed line indicates exposed conduit in unfinished areas.
Conduit — Underground
Dotted line
Conduit concealed in or under floor slab. Short dashes with wider spacing.
Homerun to Panel
Arrow with hatch marks and panel label
Arrow pointing to panelboard. Hatch marks indicate number of circuits. Labelled with panel and circuit numbers.
Junction Box
Circle with "J" or octagon
Electrical junction box. May show dimensions (AxBxC) for sizing.
Panel Board
Rectangle with label
Electrical distribution panel. Labelled with panel name (e.g., "LP-1", "EP-2").
Transformer
Two interlocking circles or rectangle with "XFMR"
Step-up or step-down transformer. May show kVA rating and voltage.
Motor
Circle with "M" inside
Electric motor. May include horsepower and voltage designation.
Disconnect Switch
Rectangle with switch symbol
Safety disconnect for isolating equipment. Labelled with amperage rating.
Fire Alarm Symbols
Symbols used on fire alarm and life safety drawings for detection, notification, and control equipment.
Fire Alarm Control Panel (FACP)
Rectangle with "FACP" label
The main fire alarm system brain. Monitors all devices and initiates alarm sequences.
Smoke Detector
Circle with "SD" or dot pattern
Detects smoke particles. Placed per NFPA 72 spacing requirements. May be photoelectric or ionisation.
Heat Detector
Circle with "HD"
Activates at a fixed temperature or rate of temperature rise. Used where smoke detectors are unsuitable.
Duct Smoke Detector
Rectangle with "DSD" on ductwork
Mounted in HVAC ductwork to detect smoke in the air handling system.
Manual Pull Station
Square with diagonal or "PS"
Wall-mounted manual alarm initiation device. Required at exits per NFPA 72 and IBC.
Horn / Strobe
Circle-square combination with "HS"
Audible and visual notification device. Must meet ADA candela and decibel requirements.
Speaker / Strobe
Similar to horn/strobe with "SS"
Voice evacuation speaker with visual strobe. Used in high-rise and large assembly occupancies.
Strobe Only
Square with "S"
Visual-only notification for areas where audible devices are not required or already covered.
Flow Switch
Circle on sprinkler pipe with "FS"
Detects water flow in sprinkler piping, indicating a sprinkler head has activated.
Tamper Switch
Circle on valve with "TS"
Monitors sprinkler control valves to detect unauthorized closure.
Plumbing Symbols
Common symbols found on plumbing drawings for fixtures, piping, and equipment.
Toilet (Water Closet)
Oval attached to rectangle (tank)
Plan view of a toilet. Floor-mounted shown with tank; wall-hung shown without.
Lavatory (Sink)
Semi-circle or oval at wall line
Bathroom sink shown as a semicircle or oval projecting from the wall.
Kitchen Sink
Rectangle with one or two basins
Single or double basin kitchen sink. May show drainboard area.
Bathtub
Large rectangle with rounded end
Standard bathtub shown as rectangle. Rounded end indicates the head.
Shower
Square with "X" or circle and drain
Shower pan shown as square with an X pattern or centre drain symbol.
Floor Drain
Circle with "FD" or square with circle
Drain set in the floor. Common in restrooms, mechanical rooms, and commercial kitchens.
Cleanout
Circle with "CO"
Access point for cleaning drain and waste piping. Required at changes in direction.
Hose Bib
Triangle at wall with "HB"
Outdoor water faucet connection. Shown as triangle projecting from exterior wall.
Water Heater
Circle with "WH"
Domestic hot water heater. May show gallon capacity and fuel type.
Cold Water
Solid line
Cold water supply piping shown as a solid line. May have "CW" label.
Hot Water
Dashed line or line with single hash
Hot water supply piping. Distinguished from cold water by dashes or hash marks.
Waste / Drain
Thick line with arrow for flow direction
Sanitary waste piping shown with heavier line weight. Arrow indicates direction of flow.
Vent
Thin dashed line
Plumbing vent piping that allows air into the drainage system to prevent siphoning traps.
Gas
Line with "G" markers
Gas supply piping. Often shown with "G" labels at intervals or a specific line pattern.
HVAC / Mechanical Symbols
Symbols used on mechanical drawings for ductwork, equipment, and air distribution devices.
Supply Duct
Parallel lines (solid)
Supply air ductwork shown as two solid parallel lines. Width typically drawn to scale.
Return Duct
Parallel lines (dashed)
Return air ductwork shown with dashed lines to distinguish from supply.
Exhaust Duct
Parallel lines with center line dashed
Exhaust air ductwork, distinguished by its own line pattern.
Flex Duct
Wavy parallel lines
Flexible ductwork connecting main duct runs to diffusers and terminals.
Duct Direction Arrow
Arrow with CFM number
Shows airflow direction and volume. Labelled with cubic feet per minute (CFM).
Supply Diffuser
Square with X inside
Ceiling-mounted supply air diffuser. Drawn to approximate size with type designation.
Linear Diffuser
Narrow rectangle with lines
Slot-type diffuser, often in ceiling or sill applications. Drawn to scale length.
Return Air Grille
Rectangle with parallel bars
Return air grille shown with horizontal or vertical lines inside the rectangle.
Fire Damper
Rectangle with "FD" at duct/wall intersection
Fusible-link damper that closes automatically in fire conditions at rated wall/floor penetrations.
Smoke Damper
Rectangle with "SD" at duct/wall intersection
Damper that closes upon signal from fire alarm system to prevent smoke migration.
Volume Damper
Butterfly shape in duct
Manual or automatic damper for balancing airflow in duct branches.
VAV Box
Rectangle with "VAV" label
Variable Air Volume terminal unit. Controls airflow to individual zones.
Thermostat
Small circle with "T"
Room temperature sensor/controller. Placed on wall at standard mounting height.
Air Handling Unit
Large rectangle with "AHU" and number
Central air conditioning unit containing filters, coils, and fans. Referenced to equipment schedule.
Roof Top Unit
Rectangle on roof plan with "RTU"
Packaged HVAC unit on the roof. Shown in plan with duct connections.
Site and Civil Symbols
Symbols used on civil engineering and site development drawings.
Contour Line — Existing
Thin dashed line with elevation number
Shows existing ground elevation. Labelled with the elevation value.
Contour Line — Proposed
Solid line with elevation number
Shows the proposed finished grade elevation after construction.
Spot Elevation
X with elevation number
A specific point elevation, used for critical areas like building corners and drainage points.
Benchmark
Triangle with elevation
A fixed reference point for vertical control during construction.
Manhole
Circle with "MH" and number
Access point for underground utilities. Labelled with size and invert elevations.
Catch Basin
Square with "CB"
Storm water inlet. Shows grate type, size, and connection to storm drainage system.
Fire Hydrant
Circle with radiating lines
Fire hydrant location on site plans. Shows distance from building and access route.
Utility Pole
Circle with dot in center
Overhead electrical utility pole location.
Deciduous Tree
Irregular circle (cloud shape)
Existing or proposed deciduous tree on landscape plans.
Evergreen Tree
Star or pointed circle
Existing or proposed evergreen tree on landscape plans.
Fence Line
Line with X marks at intervals
Indicates existing or proposed fencing. X marks represent fence posts.
Retaining Wall
Thick line with triangular hatch on high side
Shows location and retained-earth side of retaining walls.
Line Types and Weights
Standard line conventions used across all construction drawing disciplines to communicate different types of information.
Object Line (Heavy)
Thick solid line
Represents edges cut by the section plane. The heaviest lines on any drawing — walls, columns, slabs.
Object Line (Medium)
Medium solid line
Visible edges beyond the cut plane. Outlines of objects seen but not cut through.
Hidden Line
Evenly spaced dashes
Edges concealed behind other elements or below the cut plane. Items above in RCPs.
Center Line
Long dash–short dash–long dash
Indicates the center axis of columns, walls, windows, or symmetrical elements.
Property Line
Long dash–dot–dot–long dash
Shows legal property boundaries on site plans.
Setback Line
Short dashes
Indicates required building setback from property lines per zoning requirements.
Dimension Line
Thin line with arrowheads or tick marks
Shows measurements between points. Tick marks (slash) at each end in architectural; arrows in engineering.
Leader Line
Thin line with arrow to note
Connects a note or symbol to the element it describes. Arrow touches the element.
Match Line
Thick dash with note
Indicates where a drawing continues on another sheet. Labelled with the corresponding sheet number.
Demolition Line
Dashed with X marks or grey
Elements to be demolished or removed. Often shown lighter or with X marks through them.
New Work Line
Solid heavy line (darker than existing)
In renovation drawings, new construction drawn heavier than existing elements to remain.
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