Five free practice questions on blueprints, takeoffs and layout: block B of the Red Seal 403A Carpenter exam, about 14 of its 100 questions. They are in the exam's format: four options, one correct answer. Answer each one before opening the explanation. No account, no email.
01The questions
-
A waterproof-membrane deck is specified to slope 2% (1:50) away from the house for drainage. The deck joists span 3.0 m from the ledger to the outer beam. How much lower must the top of the beam be than the top of the ledger?
- 60 mm
- 15 mm
- 45 mm
- 30 mm
Show the answer
A. Correct. Drop = span × slope = 3.0 m × 0.02 = 0.060 m = 60 mm. Set the beam elevation from the ledger with a level and a 60 mm offset, or use a laser with the target elevation dropped by 60 mm. The slope must be built into the framing, not faked in the membrane.
Why not the others
B. This is a 0.5% slope, too flat to shed water reliably on a membrane. A 2% slope drops 20 mm in every metre.
C. This is 1.5%. Close, but the specification says 2%; a membrane deck that is under-sloped ponds at the low spots.
D. This is a 1% slope. A 2% slope drops 20 mm in every metre, so over 3.0 m the drop is 60 mm.
-
The structural drawings show a 2-ply 38 × 235 mm (2 × 10) lintel over a garage door. A signed change order issued after the drawings specifies a 3-ply 38 × 286 mm (2 × 12) lintel at the same opening. Which governs?
- The larger of the two, to be safe
- The drawings, because they are stamped by the engineer
- The change order, because it is the later signed document
- Whichever lintel the carpenter has on hand
Show the answer
C. Correct. A signed change order formally amends the contract documents and takes precedence over the drawings it modifies. Cross-reference the change order number against the drawings and mark the revision on the site set so the superseded detail is not built.
Why not the others
A. In this case the change order is the larger member, but choosing by size is the wrong reasoning — a change order can also reduce a member, and it still governs.
B. The change order itself is issued through the consultant and carries the same authority; it exists precisely to revise the stamped drawings.
D. Material availability never decides a structural requirement. The documents decide the size; the carpenter sources it.
-
A floor requires 24 joists of 38 × 235 mm (2 × 10) lumber, each 4.88 m (16 ft) long. How many board feet is this?
- 320 BF
- 640 BF
- 960 BF
- 480 BF
Show the answer
B. Correct. Board feet are calculated from nominal size in inches and length in feet: (2 × 10 × 16) ÷ 12 = 26.67 BF per piece; 26.67 × 24 = 640 BF. Lumber is still bought by the board foot or per piece in Canada, so the takeoff is done in nominal imperial sizes.
Why not the others
A. This treats the joists as 2 × 10 × 8 ft. Use the actual length of each piece, 16 ft, in the board-foot calculation.
C. This uses a 12 in. width (2 × 12). The joists are 2 × 10 nominal — read the size from the takeoff, not the next size up.
D. This uses 2 × 10 × 12 ft (20 BF each). Check the length: a 16 ft 2 × 10 is 26.67 BF.
-
A stairwell opening 1 000 mm wide × 3 000 mm long runs parallel to the floor joists. Which framing members must be marked on the layout to frame the opening?
- Single trimmers each side and a single header at the top of the stair only
- A beam under the opening and extra bridging
- Double trimmers each side, double headers at each end, tail joists
- Blocking between the existing joists at the opening edges
Show the answer
C. Correct. Joists parallel to a long opening are doubled on each side (trimmers) to carry the headers; the headers at each end are doubled and carry the cut-off tail joists in hangers. Mark the trimmers first so the regular joist layout can be continued past the opening, then locate the headers from the drawings.
Why not the others
A. A 3 000 mm opening needs a header at both ends to carry the tail joists, and single trimmers will not carry the concentrated load from doubled headers of that span.
B. A beam below would obstruct the stair. Floor openings are framed within the joist depth using trimmers and headers, sized from the drawings or code tables.
D. Blocking stiffens joists but does not create an opening. The joists crossing the opening must be cut and their loads transferred through headers and trimmers.
-
A floor plan gives an overall exterior wall length of 10 800 mm. The dimension string along that wall reads 3 600 mm, then 4 200 mm, then a third segment that is not dimensioned. What is the length of the missing segment?
- 3 000 mm
- 4 200 mm
- 7 800 mm
- 3 600 mm
Show the answer
A. Correct. Missing segment = overall − known segments = 10 800 − (3 600 + 4 200) = 3 000 mm. Adding up each dimension string against the overall is the basic check for errors on a drawing; if the string does not close, raise it before layout.
Why not the others
B. This repeats the second segment. 3 600 + 4 200 + 4 200 = 12 000, which does not match the 10 800 overall.
C. 7 800 is the sum of the two known segments — the subtraction from the overall was never done. The missing piece is what is left after the known segments are taken away.
D. This repeats the first segment. The string must add up to the overall dimension; 3 600 + 4 200 + 3 600 = 11 400, which overshoots.
02Answer key
| Question | Answer | Sub-task |
|---|---|---|
| Q1 | A | Lays out decks |
| Q2 | C | Interprets specifications |
| Q3 | B | Performs quantity takeoff |
| Q4 | C | Lays out floors |
| Q5 | A | Interprets project drawings |
03What block B covers
This block covers the planning and layout done before and during a build. It includes reading drawing scales, grid lines and detail callouts, specifications, RFIs and change orders, safety documents, scheduling and utility locates, material takeoffs in board feet, sheets and cubic metres, and laying out building lines, footings, joists, wall openings, rafters, stairs and guards.
The Red Seal Occupational Standard names this block “Performs planning and layout”. It carries 14% of the exam, about 14 of the 100 questions, split across three tasks. The share column is each task's weight within the block, as the standard publishes it.
| Task and its sub-tasks | Share of block |
|---|---|
| Interprets documentation Interprets project drawings; Interprets specifications; Interprets safety documentation; Interprets workplace documentation | 35% |
| Organizes work Schedules work sequence; Performs site preparation; Performs quantity takeoff; Organizes material | 24% |
| Performs layout Performs site layout; Lays out concrete formwork; Lays out floors; Lays out decks; Lays out walls; Lays out ceilings; Lays out roofs; Lays out stairs; Lays out balustrades | 41% |
04What the questions turn on
Levelling from the benchmark
Height of instrument is the benchmark elevation plus the backsight. Subtract a foresight from it to get a point's elevation, or subtract a target elevation from it to get the rod reading that sets a form at grade.
Proving a layout is square
Use the largest 3-4-5 multiple that fits the lines, since small triangles magnify marking error. On a rectangle, both diagonals must equal the calculated value; shift one corner until they match, then re-check the side lengths.
Stair and rafter arithmetic
Divide the total rise by the maximum riser and round up, then divide again for the unit rise. Total run uses one fewer tread than risers. A common rafter's run stops at the ridge face, so deduct half the ridge thickness.
When documents disagree
A written dimension governs over a scaled one, and a signed change order governs over the drawing it amends. A conflict between the architectural and structural plans goes to the consultant as an RFI before anything is laid out.
05The other blocks
The 403A exam has seven blocks. Each has its own page of free questions:
The 403A Carpenter practice exam page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.