Reading Plans, Specifications, and Layout
Chapter Introduction
This chapter covers all the skills required for the "Reading Plans, Specifications, and Layout" section of the Red Seal exam for the bricklayer trade. You must master the reading of architectural and structural drawings, interpretation of specifications, and precise layout techniques on the job site. Approximately 12 to 15% of exam questions cover this domain. Each section below corresponds to a task from the National Occupational Analysis (NOA).
2.1 Interpretation of Architectural Drawings
2.1.1 Scales and Measurements
Plans are drawn at a reduced scale. You must be able to convert plan dimensions to real dimensions and vice versa. Common scales in masonry are:
| Scale | Typical Use |
|---|
| 1:50 | General floor plans |
| 1:20 | Wall elevations, window details |
| 1:10 | Cornice details, sills, lintels |
| 1:5 | Joint details, thresholds, wall sections |
| 1:1 | Moulding profiles, templates |
Golden Rule: On a plan at a scale of 1:50, 1 cm on paper represents 50 cm (0.5 m) on site. To calculate a real dimension, multiply the measurement on the plan by the scale denominator. To draw a real dimension on a plan, divide by the scale denominator.
Example: A length of 3.75 m on a plan at a scale of 1:20 measures 3.75 m ÷ 20 = 0.1875 m = 18.75 cm on paper.
Common Pitfall: Detail plans (1:5 or 1:10) are often drawn with dimensions in millimetres. Always check the unit indicated in the title block. In Canada, commercial plans use the metric system (mm and m), but some older residential plans may be in feet and inches.
2.1.2 Standardized Lines and Symbols
Lines on a plan have precise meanings. You must recognize them instantly:
| Line Type | Meaning |
|---|
| Thick continuous line | Visible edge (wall outline) |
| Thin continuous line | Dimension, measurement, extension line |
| Broken line (dashes) | Hidden element (wall above, conduit) |
| Thin dashed-dotted line | Central axis, centre line |
| Thick dashed-dotted line | Cutting plane line (section) |
| Wavy line | Drawing break (long element interrupted) |
Masonry Symbols: Bricks are represented by parallel hatching at 45°; concrete blocks by cross-hatching or dots; natural stone by irregular shapes. Door, window, stair symbols, and levels (elevations) are standardized according to CSA A23.1 for concrete and CAN/CSA-B78.1 drawing standards for technical drawing.
Levels and Elevations: Levels are indicated in metres relative to a reference point (elevation benchmark, often the finished floor level or finished grade). A level is noted as + 0.000 for finished floor, – 0.300 for a footing, + 3.200 for a lintel. The symbol is a triangle with a centre point, accompanied by the dimension in metres to three decimal places.
2.1.3 Floor Plans, Elevations, Sections, and Details
Floor Plan: Horizontal section view at approximately 1.2 m above the finished floor. It shows wall layout, openings (doors, windows), dimensions, axes, and section markers.
Elevation: Vertical view of the exterior of a building. It shows wall heights, window sills, lintels, cornices, expansion joints, and finishing materials.
Section: Vertical cross-section view. It shows wall thickness, foundations, joists, slabs, and anchoring details.
Detail: Enlarged view (scale 1:5 or 1:2) of a specific element: window sill, threshold, parapet, wall anchor, etc.
Systematic Reading Method:
23.Read the title block (title, scale, date, revision).
24.Locate the orientation (north arrow).
25.Identify reference axes (letters and numbers).
26.Locate the main levels.
27.Follow section lines to find corresponding details.
28.Check general notes and specifications.
2.2 Reading Specifications
2.2.1 Structure of Specifications (CSC/CCDC)
In Canada, specifications are written according to the National Master Specification (NMS) or the MasterFormat format (ASTM E1557 standard). The standard format comprises 16 divisions (or 50 divisions in the recent version). For the bricklayer, the relevant divisions are:
| Division | Content |
|---|
| Division 03 | Concrete (foundations, footings) |
| Division 04 | Masonry (brick, block, stone, mortar) |
| Division 05 | Metals (anchors, lintels, reinforcement) |
| Division 07 | Waterproofing, insulation, vapour barrier |
| Division 09 | Finishes (jointing, cleaning) |
Important Clauses for the Bricklayer:
Section 04 21 00: Brick Masonry (units, mortar, installation, joints).
Section 04 22 00: Concrete Block Masonry.
Section 04 05 13: Mortar and Grout (types, proportions, strength).
Section 04 05 19: Anchors and Reinforcement.
2.2.2 Types of Specifications and Document Hierarchy
There are three types of specifications:
Descriptive Specification: Describes materials and labour in detail.
Performance Specification: Specifies expected results (strength, permeability) without dictating methods.
Product Specification: Names specific products (brands, models).
Contractual Hierarchy (in case of conflict):
45.Contract agreement (signed contract).
46.Specifications.
47.Plans (drawings).
48.Addenda (modifications published before bidding).
49.Modifications (changes after signing).
Important Rule: In case of conflict between a plan and a specification, the specification prevails in most Canadian contracts (unless otherwise indicated). However, always check the specific contract clause. Addenda take precedence over original documents.
2.2.3 Masonry Material Specifications
Specifications must state:
Bricks: Type (clay, shale, sand-lime), class (CSA A82 standard), compressive strength (MPa), water absorption (%), dimensional tolerance, colour, texture.
Concrete Blocks: CSA A165 standard (concrete blocks), density (normal, lightweight), strength (MPa), absorption.
Mortar: Type (M, S, N, O) according to CSA A179 (mortar for masonry). Volumetric proportions are:
| Type | Portland Cement | Lime | Sand |
|---|
| M | 1 | 0.25 | 3.5 |
| S | 1 | 0.5 | 4.5 |
| N | 1 | 1 | 6 |
| O | 1 | 2 | 9 |
Minimum Compressive Strength (28 days):
Type M: 17.2 MPa
Type S: 12.4 MPa
Type N: 5.2 MPa
Type O: 2.4 MPa
Mortar Type Selection based on use:
Type M: underground structures, heavy load-bearing walls, seismic zones.
Type S: load-bearing walls, exterior walls exposed to weather.
Type N: interior non-load-bearing walls, partitions.
Type O: repairs, interior non-load-bearing walls.
2.3 Layout and Staking
2.3.1 Basic Principles of Layout
Layout involves transferring plan dimensions to the site with precision. Layout errors are costly and difficult to correct. You must master:
The Reference Benchmark: An elevation benchmark is provided by the land surveyor. All elevations are measured from this point.
The Axes: Construction axes (A, B, C; 1, 2, 3) are the reference lines. Walls are positioned relative to these axes.
Tolerances: According to CSA A371 (Masonry Construction), the tolerance for wall alignment is ± 10 mm over 3 m, and ± 20 mm over 10 m. For levels, the tolerance is ± 6 mm relative to the specified level.
2.3.2 Measuring and Alignment Instruments
| Instrument | Use | Typical Accuracy |
|---|
| Spirit level (2 m) | Checking plumbness and levelness | ± 1 mm/m |
| Rotary laser level | Establishing horizontal levels over long distances | ± 1.5 mm/30 m |
| Line laser level | Vertical and horizontal wall alignment | ± 2 mm/10 m |
| Theodolite or total station | Setting out angles and axes | ± 1 second of arc |
| Steel measuring tape | Linear measurements | ± 1 mm/10 m |
| Plumb bob | Checking verticality | ± 1 mm/m |
| Chalk line | Horizontal joint alignment | ± 2 mm over 10 m |
Wall Layout Procedure:
77.Verify the provided elevation benchmark.
78.Establish the main axes using the theodolite or total station.
79.Mark the building corners with stakes and nails.
80.Install batter boards approximately 1.5 m from the corners.
81.Stretch chalk lines between the batter boards to represent the wall faces.
82.Transfer levels using the laser level or water level.
83.Check the diagonals: for a rectangle, the diagonals must be equal (tolerance ± 5 mm).
Diagonal Calculation: For a rectangle of length L and width W, the diagonal D = √(L² + W²). For example, for a building 12 m × 8 m: D = √(144 + 64) = √208 = 14.42 m.
2.3.3 Layout of Openings and Corners
Openings (doors, windows): Opening dimensions are given as clear width (finished dimension). You must add installation tolerances (generally 10 to 20 mm on each side) to determine the rough opening dimension in the masonry.
Corners: Corners must be perfectly at 90°. Use the 3-4-5 triangle method: mark 3 m on one axis, 4 m on the other, the distance between the two points must be 5 m. If not, adjust.
Expansion Joints: Their position is indicated on the plans. They must be laid out precisely (± 5 mm) as they affect wall stability.
2.3.4 Levels and Elevations in Masonry
Critical levels for the bricklayer are:
Footing Level: The top surface of the footing must be perfectly level (± 3 mm over 3 m).
First Course Level: The first course of brick must be laid on a full mortar bed, at a precise level (± 6 mm).
Window Sill Level: Sills must be at a consistent level (± 3 mm).
Lintel Level: Lintels must be installed at a precise level (± 6 mm).
Levelling Method: Use a rotary laser level to establish a reference level line. Transfer this line onto the walls using a graduated ruler. Mark the levels with a grease pencil. Check every 3 metres.
2.4 Quantity and Material Calculations
2.4.1 Calculating the Number of Bricks
The number of bricks per square metre of wall depends on the brick dimensions and joint thickness. For a standard Canadian brick (190 mm × 90 mm × 57 mm) with a 10 mm joint:
Area of one brick with joint: (190 + 10) mm × (57 + 10) mm = 200 mm × 67 mm = 0.2 m × 0.067 m = 0.0134 m².
Number of bricks per m²: 1 ÷ 0.0134 = 74.6 bricks, or 75 bricks per m² (rounded).
General Formula: N = 1 ÷ [(L + j) × (H + j)], where L = brick length, H = brick height, j = joint thickness (in metres).
Practical Table (10 mm joint):
| Brick Type | Dimensions (mm) | Bricks/m² |
|---|
| Standard | 190 × 90 × 57 | 75 |
| Modular | 190 × 90 × 90 | 53 |
| Format 200 | 200 × 100 × 75 | 63 |
| Reconstructed stone | 400 × 100 × 100 | 25 |
Add 5% waste for breakage and cutting. For a 20 m² wall in standard brick: 20 × 75 = 1500 bricks + 5% = 1575 bricks.
2.4.2 Calculating Mortar Volume
The volume of mortar per m² of wall is approximately 0.02 m³ for a 10 mm joint. For a 20 m² wall: 20 × 0.02 = 0.4 m³ of mortar.
Mortar Proportions (Type N, 1:1:6):
1 volume of Portland cement
1 volume of lime
6 volumes of sand
Yield: 1 m³ of mortar requires approximately:
Cement: 350 kg (7 bags of 50 kg)
Lime: 150 kg (3 bags of 50 kg)
Sand: 1.2 m³
Practical Calculation: For 0.4 m³ of Type N mortar: 0.4 × 350 = 140 kg of cement (3 bags), 0.4 × 150 = 60 kg of lime (2 bags), 0.4 × 1.2 = 0.48 m³ of sand.
2.4.3 Calculating Concrete Blocks
For a standard block of 400 mm × 200 mm × 200 mm with a 10 mm joint:
Area of one block with joint: (400 + 10) × (200 + 10) = 410 × 210 mm = 0.41 × 0.21 = 0.0861 m².
Number of blocks per m²: 1 ÷ 0.0861 = 11.6, or 12 blocks per m².
Add 3% waste for blocks (less breakage than brick).
2.5 Applicable Canadian Codes and Standards
2.5.1 National Building Code (NBC)
The National Building Code of Canada (NBC) is published by the National Research Council (NRC). Requirements related to masonry are found in Part 9 (residential buildings) and Part 4 (structural design). Key points:
Article 9.20.2.1: Masonry walls must be designed and constructed in accordance with CSA S304 (Design of Masonry Structures).
Article 9.20.4.1: The minimum thickness of a load-bearing brick wall is 140 mm.
Article 9.20.5.1: Masonry walls must be anchored to structural elements (joists, slabs) at maximum intervals of 1200 mm.
Article 9.20.6.1: Exterior masonry walls must be protected against moisture (vapour barrier, flashing, drip edge).
2.5.2 Specific CSA Standards for Masonry
| Standard | Title | Application |
|---|
| **CSA A82** | Fired Clay Bricks | Requirements for bricks |
| **CSA A165** | Concrete Blocks | Requirements for blocks |
| **CSA A179** | Mortar and Grout for Masonry | Mortar types, proportions |
| **CSA A371** | Masonry Construction | Tolerances, installation methods |
| **CSA S304** | Design of Masonry Structures | Structural design |
Key Requirements of CSA A371:
Section 4.2: Walls must be constructed plumb with a tolerance of ± 10 mm over 3 m.
Section 4.3: Mortar joints must have a thickness of 10 mm ± 3 mm.
Section 4.4: Joints must be full (filled with mortar) throughout the wall depth.
Section 5.1: Walls must be protected from freezing during construction (minimum temperature of 5 °C for mortar installation).
2.5.3 Other Relevant Standards
CSA B149.1: Natural Gas and Propane Installation Code (relevant for chimneys and flues).
CSA B365: Code for Chimneys and Fireplaces (construction of masonry chimneys).
CAN/CSA-A23.1: Concrete (for footings and foundations).
2.6 Quality Control Procedures
2.6.1 Pre-Installation Checks
144.Check the foundations: Level, alignment, dimensions. Footings must be clean and damp (but not saturated) before laying the first course.
145.Check the materials: Bricks must conform to specifications (colour, dimensions, strength). Damaged or spalled bricks must be rejected.
146.Check the mortar: Consistency must be plastic, neither too dry nor too wet. Mortar must be used within 2.5 hours of mixing (CSA A179).
2.6.2 Checks During Installation
Plumbness: Check verticality every 3 courses with a level or plumb bob.
Alignment: Use a chalk line to check the horizontal alignment of joints.
Joint Thickness: Check with a joint gauge. Tolerance is ± 3 mm.
Joint Filling: Joints must be full. A hollow (unfilled) joint reduces wall strength by 50%.
Course Level: Each course must be perfectly horizontal.
2.6.3 Post-Installation Checks
Cleaning: Mortar must be removed from the brick surface before it hardens. Use a stiff brush and water. Never use hydrochloric acid on clay bricks (risk of efflorescence).
Protection: Walls must be protected from frost, rain, and impact for 48 hours after installation.
Joint Finishing: Joints must be finished (concave, V-shaped, or flush) according to specifications. The concave joint is the most common for exterior walls.
2.7 Pitfalls to Avoid
159.Confusing scales: Always check the plan scale before measuring. A scale error from 1:50 to 1:20 multiplies dimensions by 2.5.
160.Ignoring addenda: Addenda modify the original plans and specifications. A candidate who does not consult them makes dimensional errors.
161.Forgetting tolerances: CSA A371 imposes precise tolerances. A deviation of ± 5 mm on a level may be acceptable, but ± 15 mm is not.
162.Confusing mortar types: Type M is stronger than Type N, but it is less workable. Use the type specified in the specifications, not the one you prefer.
163.Calculating bricks without accounting for joints: The calculation of bricks per m² must include joint thickness. Forgetting the 10 mm joint increases the brick count by 15%.
164.Neglecting waste: Always add 5% waste for bricks and 3% for blocks. Actual waste is often higher on complex job sites.
165.Misinterpreting section symbols: A misidentified section line can make you read the wrong detail. Always follow the direction of the arrows.
166.Forgetting freezing requirements: Mortar installation is prohibited when the temperature is below 5 °C, unless special measures are taken (heating, covering).
167.Confusing standards: CSA A179 (mortar) is not the same as CSA A371 (construction). Know the requirements of each standard.
168.Not checking diagonals: A building can be perfectly aligned on the axes but have non-square corners. Checking diagonals is mandatory.
2.8 Exam Tips
Read questions twice: Red Seal exam questions are designed to trap hurried candidates. Identify keywords: "according to the specifications," "in accordance with CSA A371," "maximum tolerance."
Use the correct units: The exam uses the metric system. Convert feet and inches if necessary (1 ft = 0.3048 m, 1 in = 25.4 mm).
Memorize key values: 75 bricks/m², 12 blocks/m², 0.02 m³ of mortar/m², tolerance of ± 10 mm over 3 m, minimum temperature of 5 °C.
Understand the document hierarchy: In case of conflict, specifications prevail over plans, and addenda prevail over original documents.
Practice calculations: Quantity calculation questions are common. Practice with varied examples (walls with openings, corners, return walls).
Know the mortar types: The proportions and strengths of Types M, S, N, O are classic questions.
2.9 Summary
Reading Plans: Master scales (1:50, 1:20, 1:10, 1:5), line types, masonry symbols, and levels (elevations). Systematically read the title block, orientation, axes, and notes.
Specifications: Understand the structure of the National Master Specification (divisions 03, 04, 05, 07, 09). Specifications prevail over plans in case of conflict. Addenda modify original documents.
Material Specifications: Bricks must conform to CSA A82, blocks to CSA A165, mortar to CSA A179. Mortar types M, S, N, O have specific proportions and strengths.
Layout: Use appropriate instruments (laser level, theodolite, plumb bob). Check diagonals (3-4-5 method). Respect CSA A371 tolerances: ± 10 mm over 3 m for plumbness, ± 3 mm for joint thickness.
Quantity Calculations: 75 bricks/m² (standard brick, 10 mm joint), 12 blocks/m², 0.02 m³ of mortar/m². Add 5% waste for bricks, 3% for blocks.
Standards: The NBC (Parts 4 and 9) and CSA standards (A82, A165, A179, A371, S304) govern masonry in Canada. The minimum installation temperature is 5 °C.
Quality Control: Check plumbness, alignment, joint thickness, and complete joint filling. Protect walls from frost and weather for 48 hours.
2.10 Self-Assessment Questions
188.On a plan at a scale of 1:20, a dimension measures 12.5 cm. What is the real dimension?
Answer: 12.5 × 20 = 250 cm = 2.5 m.
190.How many standard bricks (190 × 90 × 57 mm) are needed for a 15 m² wall with a 10 mm joint?
Answer: 15 × 75 = 1125 bricks + 5% = 1182 bricks.
192.What type of mortar (M, S, N, O) is required for an exterior load-bearing wall exposed to weather?
Answer: Type S (strength of 12.4 MPa).
194.What is the plumbness tolerance for a 3 m high wall according to CSA A371?
Answer: ± 10 mm.
196.A building measures 15 m × 10 m. What is the length of the diagonal?
Answer: √(15² + 10²) = √(225 + 100) = √325 = 18.03 m.
198.In case of conflict between a plan and a specification, which document prevails?
Answer: The specification.
200.What is the minimum temperature for mortar installation?
Answer: 5 °C.
202.What volume of mortar is needed for 25 m² of brick wall?
Answer: 25 × 0.02 = 0.5 m³.
204.Which CSA standard governs requirements for fired clay bricks?
Answer: CSA A82.
206.What is the method for checking that a corner is at 90°?
Answer: The 3-4-5 triangle method (or checking diagonals).
