Introduction to Construction Drawings
Reading the set
A drawing set is organized from general to specific: plot or site plan, floor plans (plan view from above), elevations (exterior faces), sections (cut-away views), and details (enlarged close-ups). The title block identifies project, sheet number, date, and designer; the revision block tracks changes; the north arrow orients the plan; grid lines locate structural members; and the scale note tells you how paper distance relates to real distance. Specifications are written requirements that complement the drawings - when they conflict, ask the designer rather than guessing.
Lines, symbols, and dimensions
Object lines show visible edges; hidden lines (dashed) show concealed features; center lines mark axes of symmetry and bolt circles; dimension lines carry the measurement with arrows or ticks at each end; extension lines project out from the object to meet the dimension line. Never scale a dimension off the drawing when a written dimension is given - the written dimension governs. Common abbreviations (CL, SYM, TYP, NTS, DWG, ELEV, VIF) appear constantly, and schedules list doors, windows, and equipment.
Worked example: using a scale
A plan is drawn at ¼ inch = 1 foot. That means ¼ inch on paper equals 12 inches real, so 1 inch on paper equals 4 feet. A wall that measures 3½ inches on the drawing is 3.5 × 4 = 14 feet long. Note that NTS means "not to scale" - never measure it.
Trap
Distinguishing dimension lines from extension lines, and remembering that scale ratios change when a drawing is copied or resized.