Residential and Commercial Brickwork

Residential and Commercial Brick Masonry

Module Introduction

This chapter covers all the knowledge required for the Red Seal masonry exam, specifically for brick construction in the residential and light commercial sectors. You will find design principles, installation methods, quantity calculations, requirements from the National Building Code of Canada (NBCC), and the classic traps that cause candidates to fail.

1. Properties and Classification of Brick

1.1 Reference Standards

Fired clay brick must conform to CSA A82.1 (Fired Clay Brick — Classification and Specifications). This standard classifies bricks into three grades based on their frost resistance and exposure:

Grade	Frost Resistance	Typical Use
Grade SW (Severe Weathering)	Excellent — resists intense freeze-thaw cycles	Exterior walls, foundations, severe frost zones
Grade MW (Moderate Weathering)	Moderate — resists moderate cycles	Interior walls, partitions, sheltered areas
Grade NW (No Weathering)	Low — does not resist frost	Interior only, never exterior

Exam Rule: For any exterior wall in Canada, Grade SW is mandatory. Grade MW may only be used in interior walls or permanently protected exterior walls (e.g., behind cladding).

1.2 Dimensions and Modules

The standard modular brick (CSA A82.1) has nominal dimensions of 200 mm × 100 mm × 75 mm (length × width × height), including the 10 mm joint. The actual dimensions are therefore 190 mm × 90 mm × 65 mm.

The 100 mm module is the basis of all quantity calculations. Each brick occupies a nominal volume of 0.0015 m³ (200 × 100 × 75 mm = 1,500,000 mm³ = 0.0015 m³).

Brick Calculation Formula per Square Metre:

For a 1 m² wall with 10 mm joints:

Modular brick: 1 m² ÷ (0.200 m × 0.075 m) = 66.7 bricks/m² (round up to 67)

With 5% waste: 70 bricks/m²

Quantity Table by Bond Type:

Bond Type	Bricks/m² (theoretical)	Bricks/m² (with 5% waste)
Stretcher (running)	67	70
Stretcher with 10 mm joints	67	70
Header	100	105
Soldier	134	141
English bond	67	70
Flemish bond	67	70

1.3 Absorption and Compressive Strength

The minimum compressive strength for a Grade SW brick is 20.7 MPa (3000 psi). For Grade MW, it is 17.2 MPa (2500 psi).

The absorption rate (CSA A82.2 test) must not exceed:

Grade SW: 17% maximum (24-hour immersion)

Grade MW: 22% maximum

Grade NW: 25% maximum

Exam Trap: A highly absorbent brick must be wetted before laying in hot weather, otherwise it will draw water from the mortar too quickly, causing incomplete hydration and poor adhesion. However, a saturated brick must never be laid — it will slide on the mortar.

2. Mortar and Joints

2.1 Mortar Types (CSA A179)

CSA A179 (Mortar and Grout for Unit Masonry) defines four mortar types, classified by decreasing strength:

Type	Proportion (cement : lime : sand)	28-Day Strength (MPa)	Recommended Use
S	1 : 0.5 : 4.5	12.5	Load-bearing walls, seismic zones, walls exposed to high winds
N	1 : 1 : 6	7.5	Non-load-bearing exterior walls, façade walls
O	1 : 2 : 9	5.0	Non-load-bearing interior walls, repairs
M	1 : 0.25 : 3.5	17.5	Structures in contact with soil, foundations, retaining walls

Exam Rule: For an exterior residential or light commercial brick wall, Type N is the most common. Type S is required for load-bearing walls or in high-wind regions. Type M is reserved for buried structures or those in contact with soil.

2.2 Consistency and Setting Time

Mortar must have a plastic consistency such that it holds its shape when pressed into a ball, but crushes easily between the fingers. The initial setting time is approximately 2 to 4 hours at 20 °C.

Critical Rules:

Mortar must be used within 2.5 hours of mixing (CSA A179).

In hot weather (> 30 °C), this time is reduced to 1.5 hours.

Re-tempered mortar (remixed with water) is prohibited — it loses strength and adhesion.

The mortar temperature must not exceed 50 °C at the time of mixing.

2.3 Joint Thickness

Joint Type	Nominal Thickness	Tolerance
Horizontal joint (bed)	10 mm	± 3 mm
Vertical joint (head)	10 mm	± 3 mm
Movement joint	15 to 20 mm	Varies by design

Exam Rule: Vertical joints must be solid (100% filled). A hollow joint reduces shear strength by 50% and allows water infiltration.

2.4 Joint Profiles

The joint profile affects water tightness and appearance:

Profile	Characteristic	Use
Concave	Best water tightness, compacts the mortar	Exterior — recommended
V-shaped	Good water tightness, decorative appearance	Exterior or interior
Flush	Flat surface, average water tightness	Interior only
Raked	Rough appearance, low water tightness	Interior decorative
Recessed	Cast shadow, low water tightness	Interior only

Exam Rule: The concave joint is the only acceptable profile for exterior walls exposed to weather. It must be made with a round tool (jointer) when the mortar is at thumb-print consistency (thumbprint remains without sticking).

3. Bonds and Layouts

3.1 Running Bond (Stretcher)

The running bond (or stretcher bond) is the most commonly used: all bricks are laid lengthwise (stretchers), with a one-quarter brick overlap (50 mm) between successive courses.

Overlap Rules:

Minimum overlap: 25% of the brick length (50 mm for a 200 mm brick).

Maximum overlap: 75% (150 mm).

Vertical joints of two consecutive courses must never align.

3.2 English Bond

The English bond alternates a course of stretchers and a course of headers. It offers better transverse strength and is used for load-bearing walls or tall walls.

3.3 Flemish Bond

The Flemish bond alternates stretchers and headers within the same course. It is more decorative but slower to execute. The strength is slightly lower than English bond.

3.4 Header Bond

All bricks are laid across (headers). Used for 90 mm thick walls (interior partitions) or curved walls.

3.5 General Laying Rules

Rule of Thirds: No vertical joint should be within 50 mm (one-quarter brick) of a vertical joint in the adjacent course.

Corner Rule: Corners must be built first, with a lead of 3 to 5 courses ahead of the rest of the wall. Each corner must be checked with a spirit level in both directions and a square for 90° angles.

Alignment Rule: The wall must be checked with a chalk line stretched between the corners. The alignment tolerance is ± 3 mm per 3 metres of length.

4. Residential Brick Walls

4.1 Non-Load-Bearing Brick Wall (Veneer)

The non-load-bearing brick wall is the most common in residential construction. It rests on the foundation and supports only its own weight. It is tied to the load-bearing wall (usually wood or concrete block) with metal ties.

NBCC Requirements (Article 9.20.5.2):

Parameter	Requirement
Minimum thickness	90 mm (one brick)
Maximum height above foundation	3.6 m (without intermediate support)
Maximum spacing between ties	600 mm horizontally, 400 mm vertically
Minimum tie embedment	25 mm into the mortar
Air space between veneer and back-up wall	25 mm minimum, 50 mm maximum

Exam Rule: Ties must be galvanized steel or stainless steel and must be flexible to allow differential movement between the brick veneer and the wood back-up wall.

4.2 Load-Bearing Brick Wall

For load-bearing brick walls (rare in modern residential construction), the minimum thickness is 140 mm (one and a half bricks) for a single-storey wall, and 190 mm (two bricks) for two storeys.

NBCC Requirements (Article 9.20.4.1):

The height-to-thickness ratio must not exceed 10:1 for an unbraced wall.

The height-to-thickness ratio must not exceed 20:1 for a wall braced by transverse walls or floors.

4.3 Flashing and Weep Holes

Flashing (coping) is mandatory at the top of any brick wall exposed to weather. It must:

Project at least 25 mm beyond the face of the wall.

Have a drip groove (cannelure) under the projection to prevent water from following the wall face.

Slope toward the exterior (minimum slope of 15°).

Flashing (waterproof membrane) must be installed:

Under the coping.

Above openings (windows, doors).

At the base of the wall (above the foundation).

Exam Rule: Flashing must slope toward the exterior and be equipped with weep holes every 800 mm maximum, placed at the base of the wall, just above the flashing.

5. Commercial Brick Walls

5.1 Cavity Wall

The cavity wall is the dominant system in light commercial construction. It consists of:

86.An interior load-bearing wall (concrete block or cast concrete).

87.A cavity of 50 to 150 mm.

88.An exterior brick veneer that is non-load-bearing.

NBCC Requirements (Articles 9.20.2.1 and 9.20.2.2):

Parameter	Requirement
Minimum cavity width	50 mm
Maximum cavity width	150 mm (beyond this, structural calculations are required)
Ties	Every 600 mm horizontally, 400 mm vertically
Insulation in the cavity	Permitted if a 25 mm air space is maintained
Flashing at the base	Mandatory, with weep holes every 800 mm

Exam Rule: The cavity must be clean — no mortar must fall into the cavity during laying. Dropped mortar creates thermal bridges and water paths. Use a mortar board or protective netting in the cavity.

5.2 Reinforced Brick Wall

In seismic zones or for tall walls, reinforced brick masonry is used. Vertical and horizontal steel bars are embedded in cavities filled with mortar or grout.

NBCC Requirements (Article 4.3.5.2):

Grout must have a minimum strength of 10 MPa at 28 days.

The minimum cavity dimension for grout is 50 mm × 50 mm.

Grout must be vibrated to ensure complete filling.

Vertical bars must be spaced at 800 mm maximum in reinforced walls.

5.3 Movement Joints (Expansion)

Movement joints are essential to accommodate thermal expansion and brick growth. Brick expands with moisture and heat — it increases in volume, unlike concrete which shrinks.

Spacing Rules (NBCC, Article 9.20.4.4):

Wall Type	Maximum Joint Spacing
Unreinforced wall	12 m
Reinforced wall	20 m
Wall with corner reinforcement	6 m at corners
Wall with openings	Joints on each side of openings > 1.8 m

Exam Rule: The movement joint must be vertical, 15 to 20 mm wide, and filled with an elastomeric sealant compatible with masonry. It must never be filled with mortar.

6. Quantity Calculations

6.1 Calculating the Number of Bricks

General Formula:

Number of bricks = (Wall area in m²) × (bricks/m²) × (1 + % waste)

Example: Wall of 8 m × 3 m with 2 windows of 1.2 m × 1.5 m.

109.Gross area: 8 × 3 = 24 m²

110.Opening area: 2 × (1.2 × 1.5) = 3.6 m²

111.Net area: 24 − 3.6 = 20.4 m²

112.Bricks required: 20.4 × 67 = 1,366.8 bricks

113.With 5% waste: 1,366.8 × 1.05 = 1,435 bricks (round up to 1,440)

6.2 Calculating Mortar

Mortar volume per m² of wall (10 mm joints):

Volume of bed joints: 1 m × 0.010 m × 0.090 m × (1 m ÷ 0.075 m) = 0.012 m³

Volume of head joints: 1 m × 0.010 m × 0.090 m × (1 m ÷ 0.200 m) = 0.0045 m³

Total volume: 0.0165 m³/m² (approximately 16.5 L/m²)

Rule of Thumb: For 1,000 bricks, allow 0.25 m³ of mortar (250 L).

6.3 Calculating Grout (for Reinforced Brick)

Grout volume = Cavity volume − Brick volume

For a 50 mm × 50 mm cavity over the full height of a 3 m wall with 10 mm bars:

Cavity volume: 0.05 × 0.05 × 3 = 0.0075 m³

Bar volume: π × (0.005)² × 3 = 0.000236 m³

Net grout volume: 0.0075 − 0.000236 = 0.0073 m³ per cavity

7. Quality Control and Tolerances

7.1 Installation Tolerances (NBCC, Article 9.20.3.1)

Parameter	Tolerance
Plumbness (per 3 m of height)	± 6 mm
Plumbness (total height)	± 12 mm
Levelness (per 3 m of length)	± 6 mm
Joint alignment	± 3 mm
Joint thickness	± 3 mm
Face flatness (per 3 m)	± 6 mm

7.2 Tests and Sampling

The following tests are required for commercial projects:

Test	Standard	Frequency
Brick compressive strength	CSA A82.2	1 lot per 50,000 bricks
Brick absorption	CSA A82.2	1 lot per 50,000 bricks
Mortar strength	CSA A179	1 set of 3 cubes per day of laying
Grout strength	CSA A179	1 set of 3 cylinders per day of grouting

7.3 Winter Protection

Cold Weather Laying Rules (NBCC, Article 9.20.3.2):

Temperature	Requirement
5 °C to 0 °C	Heat mixing water to 60 °C maximum
0 °C to −5 °C	Heat water and sand; protect the wall with tarps
−5 °C to −10 °C	Heat water and sand; use a heated enclosure
Below −10 °C	Laying prohibited unless using a heated enclosure and warmed bricks

Exam Rule: Mortar must never freeze before it has fully set (48 hours). Frozen mortar loses 50% of its final strength. Bricks must be clean, dry, and free of ice before laying.

8. Safety and Health

8.1 Scaffolding

Scaffolding must conform to CSA S269.2 (Scaffolds). Key requirements:

Maximum load: 1.9 kPa (work area) or 2.4 kPa (storage area).

Guardrails mandatory above 3 m in height.

Solid decking, with no gaps > 25 mm.

Safe access (ladder or stairway) every 9 m of length.

8.2 Crystalline Silica

Brick dust contains crystalline silica, a recognized carcinogen. Protection requirements:

Use tools with integrated dust collection when cutting.

Wear a minimum N95 respirator when cutting or grinding.

Prohibited to clean with compressed air — use a vacuum with a HEPA filter.

8.3 Lifting and Handling

Weight of a modular brick: 3.2 to 3.8 kg.

Maximum manual lifting weight: 23 kg (general rule).

Use protective gloves and steel-toed boots.

9. Traps to Avoid

Here are the most frequent errors on the Red Seal exam:

154.Confusing brick grades: Grade SW is mandatory for any exterior in Canada. A candidate who chooses MW for an exterior wall fails.

155.Forgetting waste: Brick calculations must always include a waste factor of 5 to 10%. A calculation without waste is considered incomplete.

156.Using the wrong mortar type: Type N is the most common for exterior walls. Type M is for soil contact, not façades.

157.Neglecting movement joints: A brick wall without movement joints will crack. The maximum spacing is 12 m for an unreinforced wall.

158.Ignoring the 2.5-hour rule: Mortar must be used within 2.5 hours of mixing. Re-tempering is prohibited.

159.Confusing expansion and shrinkage: Brick expands with moisture and heat. Movement joints must accommodate this expansion.

160.Forgetting weep holes: They are mandatory every 800 mm maximum above the base flashing.

161.Calculating brick quantities without deducting openings: Always subtract windows and doors from the gross area.

162.Using a flush joint on the exterior: Only the concave joint is acceptable for exterior walls.

163.Laying frozen or wet bricks: Bricks must be dry and at room temperature before laying.

10. Summary

Key Point	Value / Rule
Modular brick	200 × 100 × 75 mm (nominal), 190 × 90 × 65 mm (actual)
Bricks per m²	67 (theoretical), 70 (with waste)
Grade for exterior	SW mandatory
Mortar for façade	Type N (1 : 1 : 6)
Joint thickness	10 mm ± 3 mm
Minimum overlap	50 mm (¼ brick)
Air space (cavity)	25 to 50 mm (residential), 50 to 150 mm (commercial)
Ties	600 mm horizontally, 400 mm vertically
Weep holes	Every 800 mm maximum
Movement joints	15 to 20 mm, every 12 m maximum
Mortar working time	2.5 hours (1.5 h if > 30 °C)
Cold weather laying	Prohibited below −10 °C without heated enclosure
Plumbness tolerance	± 6 mm per 3 m

Essential Formulas:

Bricks/m² = 1 ÷ (0.200 × 0.075) = 66.7

Mortar/m² = 0.0165 m³ (10 mm joints)

Mortar for 1,000 bricks = 0.25 m³

Net area = Gross area − Opening area

Total number = Net area × 67 × 1.05 (waste)

Golden Rules for the Exam:

173.Always check the brick grade based on exposure.

174.Always include waste in calculations.

175.Always specify the mortar type based on use.

176.Always plan for movement joints on long walls.

177.Always respect the NBCC tolerances.

This chapter covers the essentials for passing the residential and commercial section of the Red Seal exam. Review the reference tables, memorize the key values, and practice quantity calculations. Good luck with your preparation.