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Concrete Calculators
Trapezoidal Footing Calculator (2026) – Sloped Foundation
Expert Guide
Calculate the total concrete volume for sloped foundations by defining base dimensions and column slopes. Perfect for structural BOQs.
⚡ Quick Answer
Trapezoidal footings save up to 20% concrete material by sloping towards the column. For professional foundation designs, visit pro.nirmansutra.com.
🛠️ How It Works
- •**Base Length (L) & Width (W):** These are the dimensions of the rectangular footing area at the very bottom.
- •**Top/Column Length (l) & Width (w):** These are the dimensions of the column cross-section where the footing slope ends.
- •**Base Height (H1):** The thickness of the uniform rectangular block at the bottom of the footing.
- •**Slope Height (H2):** The **vertical** height of the sloped section from the top of the base to the bottom of the column.
- •**Quantity & Mix:** Specify how many identical footings you need and the concrete structural grade (e.g., M20).
📐 Calculation Formula
Volume = V(Base) + V(Frustum)
V(Frustum) = (h/3) × [A1 + A2 + √(A1×A2)]
📋 Real-Life Example
Example: 1.5m x 1.5m base (0.3m height) + 0.6m slope to 0.3m x 0.3m column.
1. Base Vol = 1.5 * 1.5 * 0.3 = 0.675 m³.
2. Slope Vol = (0.6/3) * (2.25 + 0.09 + sqrt(2.25 * 0.09)) ≈ 1.23 m³.
3. Total = 1.9 m³.
⚠️ Common Mistakes to Avoid
- ✕Calculating the slope as a simple wedge instead of a frustum piramid shape.
- ✕Using diagonal length instead of vertical height for the slope portion of the footing.
- ✕Forgetting the concrete cover for reinforcing mesh at the bottom.
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❓ Frequently Asked Questions
H1 is the fixed vertical height of the base. H2 is the vertical height of the slope itself—not the diagonal edge. Both are crucial for the Frustum formula.
They save up to 20% concrete material while providing optimal load distribution from column to base. It is a cost-effective choice for heavy buildings.
Yes, even with a sloped design, the bottom rectangular base must contain a reinforcing steel mesh to handle tension from structural loads.
Stop Guessing.
Start Building.
- ✕Square Feetको भ्रममा नफस्नुहोस्।(Don't get trapped in "Square Feet" rate illusions.)
- ✓Save up to 11% on materials with an accurate BOQ.
Worth NRs. 5,000
NRs. 999 🎯
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