Blueprint Reading & Building Codes
Interpreting construction drawings, building permits, the National Building Code of Canada, and inspection requirements.
- Read and interpret floor plans, elevations, sections, and detail drawings
- Explain the purpose and scope of the National Building Code of Canada
- Describe the building permit and inspection process
- Apply the 3-4-5 method and diagonal measurement for site layout
Lección 1
Reading Construction Drawings
Types of Construction Drawings
Construction drawings (blueprints) are the language of the building industry. Every carpenter must be able to read and interpret the common types of drawings used on construction projects.
Plan Views
Floor plan: Top-down view showing room layout
Foundation plan: Footing and foundation layout
Roof plan: Ridge, hip, and valley locations
Site plan: Building placement on the lot
Vertical Views
Elevations: Exterior views of each face
Sections: Vertical cuts through the building
Details: Enlarged views of specific connections
Framing plans: Member sizes and spacing
Drawing Scales
Drawings are reduced from actual size using standard scales. Common scales in Canadian construction:
| Scale | Meaning | Typical Use |
|---|---|---|
| 1:50 | 1 mm on paper = 50 mm actual | Floor plans |
| 1:100 | 1 mm on paper = 100 mm actual | Site plans |
| 1:20 | 1 mm on paper = 20 mm actual | Wall sections |
| 1:5 | 1 mm on paper = 5 mm actual | Connection details |
Common Drawing Symbols
Carpenters must recognize standard symbols including:
- Door swing - Arc showing door opening direction
- Window - Parallel lines in wall with designation
- Dimension lines - Lines with arrows and measurements
- Section cuts - Heavy lines with directional arrows
- Centre line - Alternating long-short dashes
Reading Dimensions
Dimensions on Canadian drawings may use imperial (feet and inches) or metric (millimetres). The National Building Code of Canada uses metric, but many residential plans still use imperial. Be fluent in both.
Construction drawings include plan views (top-down), elevations (side views), sections (cut-through views), and details (enlarged connections). Always verify the scale before taking measurements from drawings.