🔎 Plan Symbols

• Concrete hatch: stipple or dot pattern.
• Masonry block: diagonal cross-hatch (CMU walls).
• Rebar: single line with bar callout (#4, #5, etc.).
• Footings: bold outline with section callouts.
• Control joints: dashed lines across slab.
• Masonry bond beam: shaded course in wall elevation.

📐 Key Calculations

• Concrete volume: length × width × thickness ÷ 27 = cubic yards.
• Block count (8×8×16): wall SF ÷ 1.125 ≈ # of blocks.
• Mortar bags: 1 bag per 35–40 blocks (typical).
• Rebar spacing: wall height ÷ spacing = bars per vertical run.
• Brick count (modular): wall SF × 7 = # of bricks.
• Grout volume (CMU walls): wall SF × thickness factor ÷ 27.

⚡ Quick Reference

• 📏 Slab thickness: 4" residential, 6"+ commercial.
• 🪢 #4 rebar: ½" dia, 0.20 in² area.
• 🧱 CMU sizes: 8×8×16 nominal (7 ⅝" actual).
• 🧱 Brick modular size: 3 ⅝" × 2 ¼" × 7 ⅝".
• 🧰 Concrete yield: 1 yd³ = 27 ft³ ≈ 81 50-lb bags of ready-mix.
• 🔨 Control joint spacing: 24–36 × slab thickness (inches).

📝 Self Test

1. How many cubic yards of concrete are needed for a 20' × 30' slab at 6" thick?
2. How many 8×8×16 CMU blocks are required for a 100 SF wall?
3. How many bricks are needed for a 250 SF veneer wall?
4. What is the diameter of #4 rebar?
5. What spacing rule is used for slab control joints?

(Answers: 1) 20×30×0.5 ÷ 27 ≈ 11.1 CY, 2) 100 ÷ 1.125 ≈ 89 blocks, 3) 250 × 7 ≈ 1,750 bricks, 4) ½", 5) 24–36 × thickness)