403A Blueprint Reading — Questions and Answers
Question 1: On a Canadian construction blueprint, what does the abbreviation 'O.C.' stand for?
- Outside corner
- On centre (Correct answer)
- Open ceiling
- Over concrete
Correct answer: On centre
O.C. stands for 'on centre,' referring to the measurement from the centre of one framing member to the centre of the next. It is one of the most common abbreviations on construction blueprints.
Question 2: What type of line on a blueprint indicates a hidden or concealed feature below the surface?
- Centre line
- Dashed line (hidden line) (Correct answer)
- Break line
- Section line
Correct answer: Dashed line (hidden line)
Dashed lines (hidden lines) represent features that exist but are not visible from the viewing angle, such as footings below grade, beams above a ceiling, or pipes within a wall.
Question 3: On a floor plan drawn at a scale of 1:50, how long would a 5-metre wall appear on the drawing?
- 50 mm
- 100 mm (Correct answer)
- 200 mm
- 500 mm
Correct answer: 100 mm
At a scale of 1:50, every 1 mm on the drawing represents 50 mm in real life. A 5-metre (5000 mm) wall would appear as 5000 ÷ 50 = 100 mm on the drawing.
Question 4: What does a section view on a blueprint show?
- The building from above
- An imaginary cut through the building to reveal interior construction (Correct answer)
- The exterior elevation from one side
- The site layout and grading plan
Correct answer: An imaginary cut through the building to reveal interior construction
A section view shows what you would see if you sliced through the building along a cutting plane. It reveals wall assemblies, floor construction, foundation details, and vertical relationships between building elements.
Question 5: In Canadian blueprint conventions, what does the symbol of a triangle with a number inside typically represent?
- A column grid reference
- An elevation reference or detail marker (Correct answer)
- A room number
- A fire rating designation
Correct answer: An elevation reference or detail marker
A triangle with a number is commonly used as a detail marker or elevation reference. The number refers to a specific detail drawing or elevation view found on another sheet.
Question 6: What information is typically found in the title block of a construction drawing?
- Material specifications and costs
- Project name, drawing number, scale, date, and designer information (Correct answer)
- Structural load calculations
- Municipal zoning requirements
Correct answer: Project name, drawing number, scale, date, and designer information
The title block, usually located in the lower right corner of a drawing sheet, contains essential identification information including the project name, drawing number, scale, revision dates, and the names of the architect or designer.
403A Blueprint Reading
On a Canadian construction blueprint, what does the abbreviation 'O.C.' stand for?