Orthographic Projection: Plans, Elevations and Sections
Orthographic projection is the core competence of this exam: deriving a plan, four elevations and at least two sections from one mental model of a building and keeping them mutually consistent. Cypriot technical drawing follows first-angle projection (EN ISO 5456-2), so the arrangement of the views on the sheet is itself a testable fact.
The first-angle arrangement
- The object sits between the observer and the projection plane; each view is projected through the object onto the plane behind it.
- The plan (top view) is placed below the front elevation; the view seen from the left is placed on the right, and vice versa.
- Views must align: all elevations in a row share the same heights; the plan shares its width with the front elevation.
- Elevations are named after the façade they show, not the direction the viewer faces: the south elevation is the face that faces south.
Sections
- A vertical cutting plane is marked on the plan with a dash-dot line, thickened at the ends, with arrows and letters (A–A). The arrows give the direction of viewing.
- Cut material is hatched at 45° in continuous thin; walls, slabs and roof structure crossed by the plane are poché.
- Everything beyond the plane is drawn as seen, in thin line; nothing in front of the plane is drawn.
- Floor levels, storey heights, roof pitch and footings must agree exactly with the elevations.
Worked example
A 1:50 plan of a two-storey house with a pitched roof over the living room; draw section A–A running north–south through the living room. Reasoning: the plane cuts the north and south external walls (thick, hatched), the ground floor slab, the first floor slab and the footings, and it crosses both roof slopes. Beyond the plane you see the partition to the hall in projection (thin continuous) and the north window as an opening between sill and lintel. The stair, being beyond the cut, appears in elevation, not in plan. Heights are taken from the same storey table used for the elevations - floor-to-floor 3.00 m is identical on every sheet.
Traps
- A mirrored plan, left–right flipped, when derived from the elevation.
- Elevation heights that contradict the section.
- Hatching a wall that lies beyond the cutting plane.
- Forgetting the ground line, external ground level and footings.
- A cutting line without arrows or letters, so the section cannot be located.
- A different roof pitch on each sheet.