Technical Drawing and Representation for Interiors
What this domain tests
This domain tests scale, line hierarchy, dimensioning convention and the ability to read and produce plans, elevations and sections that a contractor could build from - not decorative presentation drawing.
Scales and sheet sizes
- Plans: 1:50 for single rooms, 1:100 for whole flats, 1:200 for site layouts. Elevations 1:50 or 1:20. Details and sections 1:20, 1:10, 1:5.
- ISO 216 A-series: A0 841 × 1189, A1 594 × 841, A2 420 × 594, A3 297 × 420, A4 210 × 297 mm.
- Conversion: drawing length = real length ÷ scale denominator; 3,850 mm at 1:50 = 77 mm.
Line hierarchy and types (ISO 128)
- Cut elements and structural work heaviest (0.50–0.70 mm); visible outlines 0.25–0.35 mm; hatching, furniture, dimension and extension lines thinnest (0.13–0.18 mm).
- Continuous = visible edge; dashed = hidden edge; long-dash-dot = centre lines, section cut lines, grid lines.
- Do not use hidden lines where a section would communicate more clearly.
Plan, elevation, section
- A plan is a horizontal cut about 1.00–1.20 m above finished floor level, viewed downwards: door swings and window reveals appear cut.
- An elevation carries heights and widths but no depth; it shows floor line, ceiling line, openings and their heights.
- Section cut lines are drawn on the plan with arrows showing viewing direction and labelled A–A.
Dimensioning (ISO 129)
- Millimetres by default, with no unit symbol on the drawing.
- Dimension line with 45° slash or arrowhead; extension lines stop short of the object; figures sit above or left of the line and read from bottom or right.
- Two chains: overall dimensions plus opening positions; never duplicate a dimension.
- Every sheet: title block, north arrow, scale bar, room names and areas, floor finish codes, door and window references.
Worked example
A room measures 3,850 × 2,600 mm. On A3 (420 × 297 mm) at 1:50 the plan occupies 77 × 52 mm, leaving ample room for dimension chains and the title block. At 1:20 it becomes 192.5 × 130 mm, still workable. At 1:10 it becomes 385 × 260 mm - the 385 mm will not fit the printable width after margins, so move to A2 (594 mm). Keep the adjacent elevation at 1:50 too: mixing a 1:50 plan with a 1:25 elevation adjacent to it makes heights impossible to compare.
Traps that cost marks
- Mixing scales on one sheet without labelling each view.
- Dimensions given in centimetres, with unit symbols, or inconsistently.
- Broken or duplicated dimension chains that leave a position undimensioned.
- Cutting the plan at 300 mm (shows no door or window) or at 2 m.
- Omitting the scale bar, so a photocopied drawing cannot be measured.