Last reviewed 16 Sept 2026 · 8 min read
Need for conventions
Drawing every material, fitting or repetitive feature realistically would be slow and cluttered. Conventional signs and symbols are standardised simplified representations that:
- Save time and space on drawings.
- Ensure uniform interpretation by all users.
- Clearly distinguish materials in sections and fittings/services in plans.
Standards: SP 46 (engineering drawing practice), IS 962 (architectural and building drawings) and related BIS standards for electrical, welding and other symbols. Symbols not covered by standards must be explained in a legend.
Material symbols (in sections)
The following describe commonly used section symbols (exact patterns follow the standard figures):
| Material | Conventional representation |
|---|---|
| Brickwork | Parallel inclined lines (45°) — hatching; sometimes with alternate thick and thin lines, or shaded in red in coloured drawings |
| Stone masonry (rubble/ashlar) | Irregular stone outlines or hatching with stone-block pattern |
| Plain cement concrete | Dots and small triangles (aggregate) scattered uniformly |
| Reinforced cement concrete | Concrete pattern (dots and triangles) with hatching or with reinforcement bars shown as thick lines/dots |
| Earth (ground) | Diagonal hatching with short strokes below a ground line; filled/made-up earth differently |
| Sand | Fine dots (stippling) |
| Timber (wood) | Grain lines (for longitudinal section) or annual rings (cross-section) |
| Glass | Thin parallel lines or a thin outline with light shading |
| Metals (steel) | Close 45° hatching or solid black for thin sections |
| Insulation | Wavy/looped lines |
| Water / liquids | Horizontal lines with short breaks |
| Plaster | Fine stippling on the wall face |
| Rock | Irregular jointed pattern |
In coloured drawings, conventional colour washes are sometimes used (e.g. brickwork in red, concrete in grey/green, earth in brown, glass in light blue, wood in sienna), but monochrome hatching is standard for reproduction.
Building component symbols (in plans)
| Component | Representation in plan |
|---|---|
| Single-leaf door | Opening in wall with door leaf shown as a line at an angle (often 90° or 45°) and an arc showing swing |
| Double-leaf door | Two leaves and two arcs |
| Sliding door | Leaves shown as offset parallel lines with arrows |
| Window | Opening with thin parallel lines across the wall thickness (showing frame/glass) and sill |
| Ventilator | Opening shown with dashed lines (above cutting level) or a symbol with label V |
| Opening without shutter | Gap in the wall |
| Staircase | Treads as parallel lines, arrow showing "UP" from the lower floor, break line at the cutting level |
| Ramp | Arrow indicating slope direction |
| Columns | Solid black or hatched squares/circles |
| Beams, sunshades above cutting level | Dashed lines |
| Levels | Level symbol with value (e.g. +0.450) |
| North point | Arrow marked N |
| Section line | Chain line thick at ends with arrows and letters |
Openings are labelled with schedule marks — D (doors), W (windows), V (ventilators) — with sizes in a schedule.
Sanitary and plumbing symbols
Common fittings shown by simplified outlines with labels: Indian-type WC (squatting pan), European-type WC (pedestal with cistern), wash basin, sink, bath tub, shower, urinal, floor trap/nahani trap, gully trap, manhole/inspection chamber, rainwater pipe, soil and waste pipes, vent pipe, taps (bib cock, pillar cock), valves (gate, check), water meter, overhead tank.
Pipes are distinguished by line types or labels (e.g. cold water, hot water, soil, waste, rainwater); flow direction by arrows.