🏗️ ROOF SLOPE CALCULATION – FORMULA & EXAMPLE

Roof slope determines how efficiently rainwater drains and influences roof height, roofing materials, and structural design.

📐 1. FORMULA

Roof Slope (%) = (Vertical Rise ÷ Horizontal Run) × 100
🔹 Rise (h): Vertical height from eaves to ridge.
🔹 Run (b): Horizontal distance from eaves to ridge.

📏 2. CALCULATION EXAMPLE

Given:
🔹 Building width = 10 m
🔹 Roof slope = 30%
🔹 Roof type = Symmetrical gable roof
Step 1: Horizontal Run b = 10 ÷ 2 = 5 m
Step 2: Vertical Rise h = (30 ÷ 100) × 5 = 1.5 m

✅ Result: The ridge is 1.5 m above the eaves.

📊 3. ROOF ANGLE
Angle = tan⁻¹ (Rise ÷ Run)
θ = tan⁻¹ (1.5 ÷ 5) ≈ 16.7°

🔧 4. WHY IS ROOF SLOPE IMPORTANT?

✅ Improves rainwater drainage.
✅ Helps select suitable roofing materials.
✅ Determines roof height and attic space.
✅ Reduces water ponding when properly designed.

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