Lesson 1.2
Line Types: What a Line Is Made Of
Weight tells you how loud a line is. Its pattern — solid, dashed, dotted, dot-dash — tells you what kind of claim it's making. A small vocabulary that says a great deal.
Start hereA solid line and a dashed line can sit in the exact same place and mean opposite things: “this is here, you can see it” versus “this is here, but it's hidden from you.”
Six or seven patterns carry almost every claim a technical drawing needs to make. Learn them once; read any drawing forever.
01 — The core idea
Pattern is meaning
In 1.1, weight gave a line its volume. Now pattern gives it a part of speech. A continuous line states a fact you can see. A dashed line points to something concealed. A chain line (dot-dash) marks an idea, not an object — a centre, an axis, a boundary.
These are international conventions (ISO 128 again), so a drawing speaks the same line-language whether it's read in Mumbai or Munich. Tap each below to see where it's used.
Continuous line
A visible edge or cut — something really there. The default, factual line.
Tap each type. The matching line stays lit while the rest recede — that's how a trained eye reads a sheet.
02 — The working set
The lines you'll actually use
You don't need dozens. This handful covers almost everything in architecture and interiors.
| Line type | Pattern | What it means |
|---|---|---|
| Continuous (thick) | Solid, heavy | Cut edges and visible outlines — the things that are really there. |
| Dashed (hidden) | Even short dashes | Edges that exist but are concealed from this view — a beam above, a footing below. |
| Chain / centre | Long-short dot-dash | Centrelines, axes, symmetry. Marks an idea, not a physical edge. |
| Continuous (thin) | Solid, light | Dimensions, leaders, hatching, grid — the reference layer. |
| Break line | Wavy or zig-zag | “This continues, but we've cut the drawing short to save space.” |
| Phantom | Long-dash-two-short | Alternate positions or adjacent parts shown for reference — a door's full swing, a future extension. |
03 — Reading them together
Type and weight, as a pair
Line type and lineweight work together. A hidden line is dashed (type) and medium-light (weight). A centreline is dot-dash (type) and thin (weight). When you draw a line you're making two decisions at once: what part of speech, and how loud.
Even the dashes are standardised: a hidden line's dashes are short and evenly spaced; a centreline alternates a long dash with a short one; a phantom line uses a long dash with two shorts. The point isn't pedantry — it's that a trained reader recognises the pattern at a glance, the way you recognise a word's shape without spelling it out. Consistent dash patterns are what let a drawing be read fast and unambiguously across any border.
10 minutes
- On a drawing you can find (yours or any plan online), point to one continuous, one hidden, and one centreline. Name what each is claiming.
- By hand, draw a rectangle (continuous), put a hidden dashed line where something sits below, and a dot-dash centreline down its middle.
- In CAD, find the line-type menu and set the same three. Note how the software names them — the names follow the same standard.
Key terms — added to the Drawing Atlas
- Continuous line
- An unbroken line showing a visible edge or cut — a fact you can see. The default line type.
- Hidden line
- An evenly dashed line for an edge that exists but is concealed from the current view.
- Centre line
- A dot-dash (chain) line marking an axis, centre or line of symmetry — an idea rather than a physical edge.
- Break line
- A line signalling the drawing has been cut short to save space — the object continues beyond it.
- Phantom line
- A long-dash-two-short line showing alternate positions or adjacent parts shown for reference.
- Line type
- The pattern of a line (solid, dashed, dot-dash) that signals what kind of claim it makes — its “part of speech”.
Check yourself
2 quick questions — pick an answer to see why.
Q1A dashed line on a plan usually indicates…
Q2A dot-dash (chain) line is used for…
- Line type is the line's part of speech: continuous = visible fact, dashed = hidden, dot-dash = an idea (centre/axis).
- A small working set — continuous, hidden, centre, thin, break, phantom — covers nearly everything.
- Type and weight are two decisions made together for every line.
- Dash patterns are standardised (ISO 128) so any reader recognises them instantly, anywhere.
You know what to draw and how loud. Now — how do you actually hold the tool, by hand and on screen, to produce these cleanly?