Reading a working drawing and setting out accurately is the foundation for all other carpentry. Here are scale, plan-section-elevation, symbols, dimensions and module lines — and setting out on site with datum point, string line, laser and the 3-4-5 method.
Introduction
All carpentry starts with a drawing and a survey. If you cannot read the drawing precisely and transfer its dimensions to the site without losing accuracy in the process, everything that follows — rafters, walls, floors — is built on an error. Drawing reading and setting out are therefore core competencies, not something to take lightly.
Measurement temperature (measure at 20 °C): ______
A drawing is reality reduced by a fixed ratio. Scale 1:50 means 1 cm on paper is 50 cm in reality; 1:100 means 1 cm is 1 m. The smaller the detail, the larger the scale: overview drawings are often 1:100 or 1:50, while a joint detail can be 1:10, 1:5 or 1:1 (full size).
| Measuring technique | 1 cm på papir = | Typical use |
|---|---|---|
| 1:100 | 1,0 m | Drawings, overview |
| 1:50 | 0,5 m | Plan and section drawings |
| 1:20 | 0,2 m | Construction drawings |
| 1:10 / 1:5 | 0,1 m / 0,05 m | Details and assemblies |
| 1:1 | actual measurement | Template in full size |
Plan, section and elevation
A building is described from multiple views, because one image doesn't contain everything. The three basic projections are plan (viewed from above, as a horizontal section), section (an imaginary cut showing heights and construction) and elevation/façade (viewed straight on from outside). Together they give the full picture.
- 01Plan: horizontal section through the floor — shows rooms, walls, doors, windows and dimensions in the ground plane.
- 02Section: vertical cross-section — shows storey heights, construction build-up, slopes and dimensions.
- 03Elevation/facade: the building seen straight out — shows appearance, openings and materials.
- 04Detail: section at large scale showing how a joint should actually be executed.
Symbols, signatures and line types
Drawings are a professional language with fixed signs. Materials are shown with signatures (hatching for concrete, timber, insulation, masonry) and building elements with symbols (doors with opening direction, windows, stairs with walking direction arrow). Line types matter: thick, fully drawn lines are what the section cuts through; thin lines are edges behind; dotted lines are hidden parts or something above the section plane. The technical drawing rules are described in DS/EN ISO 128, and the paper formats (A0–A4) in DS/EN ISO 5457.
Dimensions and module lines
Heights are given with dimensioned levels — a level is a numerical value for a height relative to a zero point. Often a fixed building zero point is used (for example finished floor in the ground floor set to level 0.00 or a DVR90 level from the surveyor) and all other heights are measured relative to it. Module lines are a net of numbered/lettered reference lines (for example line A B C and 1 2 3) against which the building's parts are positioned. They make it possible to state a column's or wall's position unambiguously.
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