S F Johnson Consulting, LLC
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Division 04

Division 04

🧱 Division 04 — Masonry

CMU • Brick • Stone • Mortar • Grout • Reinforcement • Flashing/Weeps • Movement Joints • Cold/Hot Weather • Takeoff Math. Verify project specs, TMS 402/602 (MSJC), ASTM references.

🧭 Scope (What Div 04 Covers)

  • Concrete masonry units (CMU) — load/non-load bearing, fully/partially grouted.
  • Clay brick veneer/structural, adhered/anchored stone, cast stone.
  • Mortar, grout, reinforcement, ties/anchors, lintels, bond beams.
  • Flashing, weeps, vapor/air barriers at masonry interfaces.

🔎 Plan Symbols & Notes

  • CMU hatch (diagonal cross) with wall tag: 8" CMU @ #5 @ 32" o.c. vert, bond beam @ 48" o.c.
  • Brick veneer on elevations: coursing, control joints (CJ), expansion joints (EJ).
  • Flashing triangle at shelf angles; weeps @ 24" o.c. typical (verify).
  • Lintel schedules call spans, bearings, and steel/CMU lintel type.

📦 Common Sizes & Quick Facts

  • CMU 8×8×16 nominal (actual ~7⅝×7⅝×15⅝)
  • Half-high CMU 8×4×16 nominal
  • Brick modular 3⅝×2¼×7⅝
  • Mortar types M,S,N,O (strength ↓ → workability ↑)
  • Grout coarse/fine per cell/space
  • Weeps @ 24" o.c. (typ.), min 3/16" openings

🧪 Mortar & Grout (Typical)

  • Type S exterior, below-grade, higher strength walls.
  • Type N veneers/interior partitions (most common).
  • Grout flowable; place in lifts per spec; consolidate with vibrator/rodding.
  • Do not retemper beyond spec time; keep materials clean & consistent.

🧵 Reinforcement & Accessories

  • Vertical bars at schedule spacing (e.g., #5 @ 32" o.c.).
  • Bond beams at rows per plan; joint reinforcement @ 16" or 24" o.c.
  • Veneer anchors/ties @ 16" o.c. vertically × 32" o.c. horizontally (typical unless noted).
  • Control joints with elastomeric sealant; backer rod sized 25–50% of joint width.

🧰 Flashing & Weeps

  • Through-wall flashing at shelf angles/openings; end dams & laps shingle-style.
  • Mortar nets/drip edges to keep cavities clear; maintain 1" min air space (verify).
  • Weeps above flashings; keep clean during layup (mesh/tubes acceptable per spec).

📏 Movement Joints

  • CMU control joints (CJ): ~20–30 ft o.c. (rule-of-thumb); at corners, returns, openings.
  • Brick expansion joints (EJ): ~20–25 ft o.c.; near corners/sills; verify architect’s details.
  • Soft joints at shelf angles; compressible fillers at interfaces; sealant over backer rod.

🌡️ Cold/Hot Weather Masonry

  • Cold: heat materials, protect from freezing, cover walls; minimum temps per spec.
  • Hot: fog/mist units, shade, limit evaporation; use retarder only as allowed.
  • Do not lay on ice-coated or saturated units; protect fresh work from rain.

🧮 Quick Math & Takeoff Shortcuts

CMU Block Count

Blocks ≈ Wall SF ÷ 1.125 (for 8×8×16). Add 3–5% waste.

Half-high: use 2.25 blocks/SF.

Brick Count (Modular)

Bricks ≈ Wall SF × 7 (includes 3/8" joints). Add 5–10% waste.

Grout Volume (CMU)

CY ≈ (Wall SF × Thickness(ft) × %Cells Grouted) ÷ 27.

Example: 8" wall (0.667 ft), 50% cells → factor 0.333.

Mortar Usage

CMU: ~1 bag/35–40 blocks • Brick: ~1 bag/25 SF (varies with joints).

Vertical Bar Count

Count ≈ (Wall length ÷ spacing) + 1 (each end).

Lintel Length

Lintel = Clear span + 2× bearing (e.g., 8" each side; verify schedule).

✅ QA/Testing (Typical)

  • Unit compliance (ASTM C90 CMU; ASTM C216 brick) per spec.
  • Mortar (ASTM C270) & field tests (C780 as specified).
  • Grout (ASTM C476) — slump/strength as required.
  • Prism tests/inspections per TMS/IBC; special inspection where noted.

🦺 Safety Notes

  • Silica control for cutting/grinding; wet methods or HEPA vacs.
  • Ergonomics/rigging for units and lintels; pinch-point awareness.
  • Scaffold fall protection, toe boards, debris netting as required.

📝 Self Test

  1. How many 8×8×16 CMU are needed for a 240 SF wall (add 5% waste)?
  2. Estimate bricks (modular) for 350 SF of veneer (add 7% waste).
  3. Give a rule-of-thumb spacing for CMU control joints.
  4. Where are brick expansion joints typically located?
  5. Compute grout CY for 600 SF of 8" CMU wall with 50% cells grouted.
  6. What mortar type is common for exterior CMU walls below grade?
  7. List two key elements of a through-wall flashing detail.
  8. How many vertical #5 bars for a 48' wall @ 32" o.c. (count ends)?
  9. What is the lintel length for a 6'-0" opening with 8" bearing each side?
  10. Name one silica control method when cutting CMU.

Answers: (1) 240 ÷ 1.125 ≈ 213; +5% ≈ 224 blocks. (2) 350 × 7 ≈ 2450; +7% ≈ 2622 bricks. (3) ~20–30 ft o.c. (verify plans). (4) ~20–25 ft o.c., at corners/returns/sills. (5) 600×0.667×0.5 ÷ 27 ≈ 7.4 CY. (6) Type S. (7) End dams, shingled laps, weeps @ 24" o.c., cavity clear (any two). (8) 48' ÷ 2.667' ≈ 18.0 → 18 spaces + 1 ≈ 19 bars. (9) 6' + 0.67' + 0.67' ≈ 7.33' (use 7'-4" or per schedule). (10) Wet cutting or HEPA-equipped vacuum.