Reading Blueprints & Construction Drawings
Construction drawings (still often called blueprints) show what’s being built, where everything goes and how it fits together. Knowing how to read them makes you more valuable on the crew, and helps you spot hazards before you reach them.
- Construction
Photo: a foreman and apprentice reviewing a floor plan on a tablet at the jobsite
Types of sheets
| Sheet prefix | Discipline | Shows |
|---|---|---|
| C / L | Civil, landscape | Site layout, grading, utilities, paving |
| A | Architectural | Floor plans, elevations, sections, doors, finishes |
| S | Structural | Foundations, framing, steel, rebar, connections |
| M / P / E / FP | Mechanical, plumbing, electrical, fire protection | Ducts, piping, panels, circuits, sprinklers |
Basics
- Title block: project, sheet number, date, and revision history. Always check you have the latest revision.
- Scale: for example, 1/4″ = 1′-0″ means each quarter inch on paper equals one foot. Use written dimensions, not a ruler on the paper, whenever possible.
- Legend and symbols: each set defines its symbols and abbreviations, usually on the first sheets.
- Views: plans look down from above, elevations look at a side, sections cut through to show what’s inside, and details zoom in.
- Callouts: circles or tags that point to a detail or section on another sheet, such as “3/A501” (detail 3 on sheet A501).
- Specifications: a separate book with materials, products and methods. If drawings and specs conflict, ask.
Using drawings for safety
- Find floor openings, shafts, skylights and roof edges before you get there. See Holes & Floor Openings.
- Locate existing and new utilities on site plans, and still call 811 before digging. See Call 811.
- Check for post-tensioned slabs before drilling or coring. See Core Drills.
- Note heavy items and their locations when planning lifts and shoring.
- Use drawings in your pre-task planning. See Job Hazard Analysis.
Field conditions differ from drawings. Old buildings often hide wiring, pipes and structural changes that never made it onto the plans. Verify before cutting or demolishing. See Hidden Wiring.
Quick check before you build
- Latest revision in hand
- Scale and dimensions understood
- Related details and sections looked up
- Conflicts or questions sent to the foreman (often through an RFI)
Standards & references
- See also: Basic Construction Math · Apprenticeships
Last updated: