Masonry — Category 4

Masonry is one of the oldest building trades on earth, and one of the most demanding. Every block, every brick, every stone that goes into a church wall carries the weight — literally — of the building above it and the congregation inside it. There are no shortcuts, no do-overs, and no hiding sloppy work behind drywall. A masonry wall is its own finish. This guide covers skills 4.01 through 4.17: everything from laying the first course of CMU on a footing to cleaning the finished facade and striking the scaffolding.

1. Concrete Block Laying (CMU) — Skill 4.01

Concrete masonry units are the backbone of church construction in Ontario. Foundation walls, load-bearing backup walls, elevator shafts, stairwells, mechanical rooms — CMU goes in first and carries everything else. On most HCMI projects, the block crew is on site before any other trade except the concrete gang, and they set the pace for the entire building envelope.

CMU Sizes & Specifications (CSA A165)

All CMU used on church projects must conform to CSA A165.1 (CSA Standards on Concrete Masonry Units). The table below lists the units you’ll encounter most often on church projects.

Laying Procedure

Start every wall by dry-laying the first course without mortar. This lets you establish the bond pattern, locate the control joints, confirm the block spacing at door and window openings, and identify any units that need cutting. Measure twice. Mark the footing with a lumber crayon. Then pick up the blocks and start for real.

1. Spread the bed joint. Throw a full mortar bed on the footing — 25 mm to 30 mm thick, roughly 15 mm wider than the face shell on each side. For the first course, always use a full mortar bed (not face-shell bedding) to achieve maximum bond to the concrete footing.
2. Set the corner leads. Build up three to five courses at each corner or control joint, checking plumb with a 1200 mm level on every course. The leads establish the plane of the wall — if your leads are wrong, every block between them will be wrong too.
3. Run the line. Stretch a mason’s line from lead to lead, one course at a time. The top outside edge of each block must just touch the line without deflecting it. If you’re pushing the line, you’re out.
4. Butter the head joints. Apply mortar to the ears (face shells) of each block before setting it. Push the block down into the bed joint and against the adjacent block in one smooth motion. Target 10 mm head and bed joints throughout.
5. Check, check, check. Level across the top. Plumb the face. Straighten with the line. Verify coursing height with a storey pole every 600 mm of wall height. Three courses of standard 200 mm CMU plus mortar joints should equal exactly 600 mm.

Bond Patterns for CMU

Running bond (half-bond) is the standard for structural CMU walls per CSA A371. Stack bond is occasionally specified for architectural block walls in church lobbies or fellowship halls, but it requires horizontal joint reinforcement at every course and must be specifically engineered. Never switch bond patterns without consulting the structural drawings.

2. Brick Laying & Stone Veneer — Skills 4.02, 4.03, 4.04

If CMU is the muscle of a church wall, brick and stone are the face. Veneer work is where craftsmanship shows — or doesn’t. A beautifully laid brick facade on a new sanctuary says “this church was built to last.” Sloppy joints, stained brick, or misaligned coursing says something else entirely. On HCMI projects, veneer quality is strongly recommended.

Skill 4.02 — Face Brick / Modular Brick

Standard modular brick in Canada is 90 mm × 57 mm × 190 mm (actual). Three courses of modular brick plus three 10 mm bed joints equal 200 mm — which means brick coursing lines up perfectly with CMU coursing at every third course. This isn’t a coincidence; it’s the reason modular brick exists, and it’s the reason your wall ties land where they’re supposed to.

Before you lay a single brick on a church facade, pull units from at least five different cubes and blend them on the scaffold. Brick colour varies from cube to cube — even within the same production run. Blending prevents colour banding that will be visible for the life of the building. This takes time. Do it anyway.

Skill 4.03 — Natural Stone Veneer

Natural stone veneer brings an unmistakable presence to a church building — limestone facades, granite bases, or fieldstone feature walls that ground the structure to the landscape. But natural stone is heavy, irregular, and unforgiving of poor technique.

• Sorting and selection: Lay out stone on the ground near the wall and arrange by size, colour, and thickness before lifting a single piece to the scaffold. Plan your pattern on the ground where you can step back and see it.
• Full mortar coverage: Back-butter every stone to achieve full contact — no voids behind the veneer. Voids trap moisture, and moisture destroys stone walls from the inside out.
• Minimum bearing: Each stone must bear on the stone below it by at least 25 mm. Never float a stone on mortar alone; mortar is not structural adhesive.
• Corbelling limits: Do not project any stone more than one-third of its bed depth beyond the face of the stone below, and never more than 25 mm per course.
• Pointing: Rake joints to a consistent depth (12 mm to 15 mm) and point with Type S mortar coloured to the architect’s specification. On church facades, mortar colour is always a design decision — confirm with the architect before mixing.

Skill 4.04 — Manufactured Stone Veneer

Manufactured (cultured) stone veneer is lighter than natural stone — typically 25 kg/m² versus 75–120 kg/m² for natural — and doesn’t require a brick ledge or shelf angle in most cases. It’s increasingly common on church projects for gable ends, entrance features, and interior accent walls in sanctuaries.

Installation follows a lath-and-scratch-coat method on wood-frame or steel-stud substrates. Apply two layers of Grade D building paper or a weather-resistive barrier, then self-furred galvanised metal lath fastened with corrosion-resistant fasteners at 150 mm on centre. Apply a 12 mm to 19 mm scratch coat of Type S mortar, scarify, and allow to cure for 48 hours minimum before setting the stone.

3. Mortar, Grout & Reinforcement — Skills 4.05, 4.06, 4.07

Mortar and grout are the lifeblood of a masonry wall. The blocks and bricks are just the bones — it’s the mortar that bonds them, the grout that fills them, and the reinforcing steel that ties the whole assembly together into a structural system. Get the mortar wrong and nothing else matters.

Skill 4.05 — Mortar Mixing & Preparation (CSA A179)

All mortar must conform to CSA A179 (Mortar and Grout for Unit Masonry). The standard defines mortar types by proportion or by property — we typically specify by proportion because it’s simpler to verify on site.

Mixing procedure: Add roughly three-quarters of the water to the mixer first, then add half the sand, then the cement and lime, then the remaining sand, then adjust water to achieve proper workability. Mix for a minimum of three minutes and a maximum of five minutes after all materials are in the drum. Mortar should hang on a trowel held at 45 degrees without sliding off — the classic “trowel test.”

Skill 4.06 — Grout Filling (Reinforced Masonry)

Grout is not mortar. Grout is a fluid, high-slump cementitious fill that flows into the cores of CMU to encase reinforcing steel and create a solid, reinforced structural member. Per CSA A179, grout must have a minimum compressive strength of 12.5 MPa at 28 days and a slump between 200 mm and 250 mm.

• Clean-out openings: For lifts exceeding 1500 mm, provide clean-out openings at the base of the wall to allow removal of mortar droppings and debris before grouting. Inspect every cell that will be grouted.
• Pour height limits: Per CSA A371, grout pour height must not exceed 4800 mm for fine grout in cells 50 mm × 75 mm or larger. On tall sanctuary walls, plan your grouting lifts before you start laying block.
• Consolidation: Mechanically vibrate all grout lifts using a pencil vibrator (25 mm head) inserted into each grouted cell. Reconsolidate within 30 minutes as the grout settles and absorbs water into the CMU.

Skill 4.07 — Masonry Reinforcement Placement

Reinforcement in masonry follows the structural drawings — period. Vertical bars are set in the CMU cores before grouting; horizontal bars are laid in bond beam courses (U-shaped or knock-out lintel blocks). Ladder or truss-type horizontal joint reinforcement is embedded in the bed joints at specified intervals, typically every 400 mm vertically.

• Vertical bars must be held in position by positioners (bar chairs or clips) to maintain the required cover — minimum 15 mm clear from the inside face of the CMU shell.
• Lap splices follow the engineer’s schedule. Typical minimums: 40 bar diameters for 10M, 15M, and 20M bars in fully grouted cells.
• Do not bend reinforcing steel in the field without engineering approval. If a bar doesn’t fit, call the engineer — don’t improvise.

4. Lintels, Flashing & Moisture Management — Skills 4.08, 4.09, 4.10

Water is the enemy of every masonry wall. It will find any gap, any crack, any poorly lapped flashing, and it will get inside the wall cavity. Once inside, it corrodes ties, degrades insulation, stains finishes, and eventually undermines the structural integrity of the wall itself. Lintels, flashing, and weep holes are the three-part system that manages water — and every part must be installed correctly.

Skill 4.08 — Lintel & Shelf Angle Installation

Steel lintels carry the masonry above window and door openings. Shelf angles carry the entire weight of the brick veneer at each floor line and transfer it back to the structural frame. Both are critical structural elements.

• Lintels: Size per the structural drawings. Standard loose steel lintels are hot-dip galvanised. Minimum bearing at each end: 100 mm for spans under 1800 mm; 200 mm for spans over 1800 mm. Verify the lintel is level before laying masonry over it — shim with non-compressible pads, never mortar scraps.
• Shelf angles: Typically L-shaped galvanised steel fastened to the concrete or steel structure with expansion bolts or welded clips at 600 mm on centre (or as engineered). Leave a 10 mm to 15 mm soft joint directly below the shelf angle, filled with backer rod and sealant — never mortar. This joint allows for vertical movement of the structure and thermal expansion of the masonry.
• Deflection: The shelf angle must not deflect more than L/600 under full dead load of the supported masonry. Confirm with the engineer before commencing brickwork above the angle.

Skill 4.09 — Through-Wall Flashing Installation

Through-wall flashing is a waterproof membrane installed at every point where water might penetrate or accumulate within the wall: at the base of the wall, above every shelf angle, above every lintel, at every window head, and at roof-to-wall intersections. On a typical HCMI church with a complex roofline, there can be dozens of flashing locations.

• Material: Self-adhering rubberised asphalt membrane, stainless steel, or copper as specified. Most HCMI projects use self-adhering membrane with stainless steel drip edges.
• Lapping: End laps minimum 150 mm, sealed with compatible mastic. Dam the ends of each flashing piece by turning up 25 mm at termination points to prevent water from running off the ends into the wall.
• Extend beyond the face: Flashing must extend to the exterior face of the veneer and turn down to form a drip edge. Do not cut flashing flush with the mortar joint — it must project at least 6 mm to shed water.
• Protect during installation: Flashing is easily punctured by mortar droppings, scaffold brackets, and careless foot traffic. Once flashing is in place, treat it as fragile until it is fully covered by masonry.

Skill 4.10 — Weep Hole & Vent Installation

Weep holes are the exit points for any water that reaches the flashing. Without them, the water has nowhere to go and the flashing is useless. On church construction projects, a common approach is to use open head joints (omit the mortar from the head joint) at 600 mm on centre, directly above every flashing location. Some specifications call for cotton wicks or cellular plastic weep inserts to prevent insect entry while allowing drainage — follow the architect’s detail.

Vents (air-space vents) at the top of the cavity allow airflow that promotes drying of the cavity space. Install vents at the top of each storey or at the soffit line, spaced per the specification. The combination of weep holes at the bottom and vents at the top creates a convective loop that keeps the cavity dry between rain events.

5. Cavity Wall Construction & Wall Ties — Skills 4.12, 4.13

The masonry cavity wall is the standard wall assembly for church construction in Ontario. It consists of an inner wythe (typically CMU or steel studs), an air space (cavity), insulation, and an outer wythe of brick or stone veneer. The two wythes are connected by corrosion-resistant wall ties that transfer lateral (wind) loads from the veneer to the structure while allowing differential movement between the wythes.

Skill 4.12 — Cavity Wall Construction

The cavity wall works because of the air space. That 25 mm minimum clear cavity between the back of the veneer and the face of the insulation is the drainage plane — it’s where water that penetrates the veneer runs down to the flashing and out through the weep holes. Bridge the cavity with mortar, and you’ve just created a highway for water to cross into the building.

• Minimum cavity width: 25 mm clear air space from the back face of the veneer to the face of the insulation. Many HCMI projects specify 50 mm for better drainage and easier construction.
• Keep the cavity clean: Use a cavity drainage board at the base of each storey. Lay a board across the wall ties during construction to catch mortar droppings, and remove it at the end of each day. A clean cavity is a dry cavity.
• Insulation: Extruded polystyrene (XPS) or mineral wool rigid boards, mechanically fastened or adhered to the backup wall. Insulation must be tight to the backup with no gaps that allow convective air loops behind the insulation.
• Weather-resistive barrier: Apply an air/vapour barrier to the exterior face of the backup wall (or insulation, depending on the wall design) before installing the veneer. This is the second line of defence after the veneer itself.

Skill 4.13 — Wall Tie Installation (CSA A370)

Wall ties must comply with CSA A370 (Connectors for Masonry). On HCMI projects, we typically use adjustable two-piece stainless steel ties that allow vertical adjustment between the backup and veneer courses.

• Spacing: Maximum 600 mm horizontal, 400 mm vertical (one tie per 0.24 m²). Increase density to 300 mm horizontal within 300 mm of all openings, corners, and tops of walls.
• Embedment: Minimum 50 mm embedment in each mortar joint. The tie must be fully embedded in mortar — not just resting on the face shell.
• Slope: Ties must slope slightly downward toward the exterior (no more than 1:6) to prevent water from tracking inward along the tie.
• Material: Stainless steel (Type 304 minimum) for all exterior wall ties. Galvanised ties are acceptable for interior masonry only. In a cavity wall, the tie lives in a moist environment for the life of the building — galvanising will eventually corrode.

6. Joint Tooling, Cutting & Finishing — Skills 4.11, 4.14, 4.16

Skill 4.11 — Joint Tooling & Pointing

Joint tooling (or “striking”) compresses the mortar at the face of the joint, densifying the surface and improving both weather resistance and appearance. On a church facade that people look at every Sunday, the quality of the tooling is the difference between a wall that looks intentional and one that looks accidental.

• Timing: Tool joints when the mortar is “thumbprint hard” — firm enough to hold a thumbprint impression without smearing, but not so hard that the tool slides without compressing. On a warm day, this window can be as short as 20 minutes.
• Concave joint: The standard for most HCMI exterior masonry. A half-round jointer is pressed firmly along the mortar joint, creating a smooth, slightly concave surface that sheds water. Tool horizontal joints first, then vertical.
• V-joint: Common on CMU walls where a more pronounced shadow line is desired. Uses a V-shaped jointer.
• Raked joint: Mortar is raked out to a uniform depth (typically 6 mm to 10 mm) for a deep shadow effect. Not recommended for exterior walls in Ontario’s freeze-thaw climate unless specifically engineered, as the exposed ledge traps water.
• Flush joint: Mortar cut flush with the face of the masonry. Acceptable but less weather-resistant than concave or V-joints.

Repointing: Where joints are damaged, have voids, or were not properly tooled, rake out the defective mortar to a depth of at least 15 mm (twice the joint width) and repoint with fresh mortar matched in type, colour, and tooling profile. On church restoration work, mortar matching is critical — a botched colour match is visible for decades.

Skill 4.14 — Masonry Cutting (Wet Saw & Grinder)

Cutting masonry units is a daily reality on any church project. Window openings, door frames, angled walls, decorative details — all require precise cuts. The two primary tools are the masonry wet saw and the angle grinder with a diamond blade.

• Wet saw: The preferred tool for precision cuts on brick and stone. The water supply suppresses dust, cools the blade, and produces a clean, accurate cut. Use for all cuts that will be visible in the finished wall.
• Angle grinder: Faster and more portable than the wet saw, but produces significant dust and a rougher cut. Use for cuts that will be concealed (behind jambs, in mortar joints, etc.) or for scoring blocks before snapping.
• Brick hammer & chisel: Traditional method for rough cuts and trimming. Still useful for quick adjustments on site, but should not replace the saw for finish work on a church facade.

Skill 4.16 — Control Joint & Expansion Joint Installation

Masonry moves. CMU shrinks as it cures and dries; brick expands permanently as it absorbs moisture from the atmosphere (a process called “moisture expansion”); and all masonry expands and contracts with temperature changes. Without properly located movement joints, the wall will crack — not if, but where and when.

• Control joints (CMU): Vertical joints placed at intervals not exceeding 6 m (or as engineered) to accommodate shrinkage cracking. The joint is formed by aligning the vertical head joints in a continuous line, inserting a foam backer rod, and sealing with an elastomeric sealant. Do not bridge control joints with horizontal reinforcement — the whole point is to let the wall move at that location.
• Expansion joints (brick): Vertical joints placed at intervals not exceeding 6 m to 9 m (depending on exposure and colour — darker brick absorbs more heat and requires closer spacing) to accommodate irreversible moisture expansion and thermal movement. Fill with compressible foam filler and seal with sealant compatible with the masonry.
• Locations: At changes in wall height, at changes in wall thickness, at offsets and setbacks, at one or both sides of window and door openings, and at building corners (within 3 m of the corner for brick expansion joints). Follow the structural engineer’s joint layout — these are not optional details.

7. Masonry Cleaning (New Construction) — Skill 4.15

New masonry cleaning is the final act of the mason’s work, and it’s where a lot of otherwise good masonry goes wrong. Mortar smears, construction stains, efflorescence, and handling marks must be removed before the congregation sees the finished building. But aggressive or improper cleaning can cause permanent damage that’s worse than the stains you were trying to remove.

Cleaning Sequence

1. Wait. Do not clean new masonry until the mortar has cured for a minimum of 7 days. Cleaning freshly laid masonry dissolves the mortar joints, weakening the bond and staining the brick with dissolved cement paste — a milky white haze called “acid burn” that is nearly impossible to remove.
2. Pre-wet. Saturate the wall with clean water from the top down. This prevents the cleaning solution from being absorbed deep into the masonry pores, which would cause discolouration and efflorescence.
3. Apply cleaning solution. Use a proprietary masonry cleaning solution recommended by the brick manufacturer — never raw muriatic acid. Dilute per manufacturer’s instructions (typically 1:10 to 1:20 for proprietary cleaners). Apply from the bottom up to prevent streaking caused by solution running down dry masonry.
4. Scrub. Agitate with a stiff-bristle nylon brush or non-metallic scrub pad. Never use wire brushes on face brick — the metal leaves dark marks that are permanent.
5. Rinse. Rinse thoroughly from the top down with clean, low-pressure water. Ensure all cleaning solution is completely removed. Residual acid left in the masonry will cause ongoing efflorescence and mortar deterioration.
6. Test panel. Always clean a test panel (at least 1 m²) in an inconspicuous location first and evaluate the result after 24 hours before proceeding with the full building.

8. Scaffolding & Material Handling — Skill 4.17

Masonry is heavy work performed at height. A standard cube of brick weighs approximately 1,800 kg; a cube of CMU weighs up to 2,000 kg; and a pallet of mortar weighs 1,360 kg. All of that material must be lifted to the scaffold, distributed along the wall, and placed by hand — brick by brick, block by block. Scaffold planning and material handling are as critical to a safe, productive masonry operation as the laying itself.

Scaffold Requirements (O. Reg. 213/91)

• Design: All scaffolding must be erected, altered, and dismantled by competent workers under the supervision of a competent person, in accordance with O. Reg. 213/91 (Construction Projects) under the Occupational Health and Safety Act. Frame scaffolds exceeding 15 m in height or any unusual configuration require a professional engineer’s design.
• Working platform: Minimum width 500 mm for masonry work, though 1000 mm or wider is standard practice. Planks must extend at least 150 mm beyond the bearer but not more than 300 mm. Secure all planks against displacement.
• Guardrails: Top rail at 1050 mm ± 50 mm above the platform, mid-rail at approximately mid-height, and a toeboard at least 100 mm high at the platform edge. All open sides and ends must be guarded.
• Access: Ladders or stairways at each work level. Climbing the scaffold frames is prohibited.
• Loading: Never exceed the rated load of the scaffold. A typical frame scaffold section can carry 1,100 kg to 2,200 kg depending on configuration — check the manufacturer’s tables and the engineer’s design if applicable. Distribute materials evenly along the platform, not stacked at one point.

Material Handling

Getting materials to the mason is the job of the labourer, and it’s a job that makes or breaks productivity. A skilled mason can lay 400 to 500 bricks per day — but only if the material is at hand when needed. Starve the mason and the whole wall slows down.

• Forklift / telehandler: The primary tool for loading scaffold platforms. Load cubes of brick and block at platform level using a rough-terrain forklift or telehandler with forks. Stage materials at multiple locations along the scaffold to minimise horizontal carry distances.
• Mortar delivery: Mix mortar at grade and transport to the scaffold in mortar tubs using a hoist, forklift, or bucket brigade depending on the scaffold configuration. Never carry mortar boards up ladders — use the mechanical hoist.
• Block stacking: Stack CMU no more than two courses high on the scaffold platform to prevent toppling. Orient blocks with the open cores facing up for easy handling and to allow the mason to butter the web for full mortar bedding when required.
• Brick cubing: Break down cubes and stack brick within arm’s reach of the mason in manageable quantities (approximately 50 to 80 bricks per station). Keep the scaffold tidy — trip hazards on a scaffold are fall hazards.

Putting It All Together

Masonry on a church project is a coordinated effort that brings together 17 distinct skills into a single, integrated wall system. The CMU crew lays the backup and sets the reinforcement. The grout truck fills the cells. The brick and stone masons build the veneer. The labourers keep the scaffold loaded and the cavity clean. The foreperson reads the drawings, manages the movement joints, checks the flashing, and makes sure every tie is embedded and every weep hole is open.

When it’s done right, you get a wall that will stand for a hundred years — keeping the rain out, holding the heat in, and looking the same the day the congregation moves in as it will the day their grandchildren inherit it. That’s the standard. That’s what the Brick and Stone Mason 401A certification is about. That’s what HCMI expects on every project.

Masonry is slow. It is heavy. It is demanding. And it is permanent. Every course you lay is a record of your skill, your care, and your attention to the craft. Build the wall like someone is going to look at it every Sunday for the next century — because they will.