Building Drawing and Civil Engineering Drawing Basics
This domain tests plans, elevations and sections of simple buildings, standard scales, symbols and hatching. You must be able to read and produce a small building drawing with correct conventions.
Basics
A plan is a horizontal section cut about 1.2 m above floor level, looking down. An elevation shows the outside face; a section shows the cut through walls, floor and roof. Use a north line and a title block. Dimensions in building drawing are in millimetres, usually to the nearest 5 or 10 mm. Common scales: 1:100 for plans, 1:50 for details, 1:1000 for site plans.
Conventions
- Brickwork in section: diagonal hatching at 45°; stone: irregular blocks; concrete: dots and small triangles.
- Doors: quarter-circle swing; windows: double or triple lines in the wall opening.
- Wall thickness for a 230 mm brick wall is drawn 230 mm; half-brick partition is 115 mm.
- Show floor levels, plinth level and lintel level with a level symbol.
Worked example
A room is 4.0 m × 3.0 m with 230 mm walls. At 1:50, 4.0 m becomes 4000/50 = 80 mm, 3.0 m becomes 60 mm, and the wall becomes 230/50 = 4.6 mm. Draw the outer rectangle 80 + 2(4.6) by 60 + 2(4.6) = 89.2 mm × 69.2 mm, then the inner room rectangle. The reasoning is that every dimension is divided by the scale factor, and wall thickness is added on both sides.
Traps
Drawing the plan as a roof view instead of a cut at 1.2 m is wrong. Do not forget the door swing or the window opening. Mixing scales on one drawing confuses dimensions. Hatches should be thin and evenly spaced, not freehand scribbles.