403A Blueprint Reading 2 — Questions and Answers
Question 1: What does the abbreviation 'EL.' or 'ELEV.' indicate on a construction drawing?
- Electrical panel
- Elevation or height above datum (Correct answer)
- Elevator shaft
- Elongated dimension
Correct answer: Elevation or height above datum
EL. or ELEV. indicates elevation — the vertical height of a point measured from a reference datum, typically expressed in metres above sea level or above an established benchmark on site.
Question 2: On a site plan, what do contour lines represent?
- Property boundaries
- Underground utility locations
- Points of equal elevation on the ground (Correct answer)
- Setback requirements from the property line
Correct answer: Points of equal elevation on the ground
Contour lines connect points of equal elevation on a site plan, showing the topography and slope of the land. Closely spaced contour lines indicate steep terrain, while widely spaced lines indicate gentle slopes.
Question 3: What is the purpose of a specifications book (spec book) that accompanies a set of construction drawings?
- To provide an estimate of material costs
- To describe material quality, installation methods, and performance requirements not shown on drawings (Correct answer)
- To list the subcontractors approved for the project
- To outline the construction schedule and milestones
Correct answer: To describe material quality, installation methods, and performance requirements not shown on drawings
Specifications complement the drawings by detailing material standards, acceptable products, installation procedures, quality assurance requirements, and performance criteria that cannot be effectively communicated through drawings alone.
Question 4: What does a centre line symbol (long dash, short dash, long dash pattern) indicate on a blueprint?
- A cut line for a section view
- The centre axis of a symmetrical feature, opening, or structural member (Correct answer)
- A property boundary line
- An overhead obstruction
Correct answer: The centre axis of a symmetrical feature, opening, or structural member
The centre line symbol uses an alternating long-dash, short-dash pattern to indicate the centre axis of symmetrical objects such as columns, windows, doors, walls, or circular features.
Question 5: When reading a roof plan, what does the arrow direction typically indicate?
- The prevailing wind direction
- The direction of roof slope (downward) (Correct answer)
- North orientation
- The direction of rafter installation
Correct answer: The direction of roof slope (downward)
On a roof plan, arrows indicate the direction of the roof slope, pointing downward toward the eaves where water drains. The slope or pitch is typically noted alongside the arrow.
Question 6: In the CSA standard for construction drawings used in Canada, what sheet designation prefix is used for structural drawings?
- A (Architectural)
- S (Structural) (Correct answer)
- M (Mechanical)
- E (Electrical)
Correct answer: S (Structural)
In Canadian construction drawing standards, structural drawings are prefixed with 'S' (e.g., S-101, S-201). This follows CSA conventions similar to the National CAD Standard for organizing drawing sets.
403A Blueprint Reading 2
What does the abbreviation 'EL.' or 'ELEV.' indicate on a construction drawing?