1. What is Footing Size Calculation?

Footing size calculation determines the required area of a foundation footing based on the applied load and the soil's allowable bearing capacity. This ensures the foundation can safely support the structure without excessive settlement.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Load \) — Total load applied to the footing (lbs)
• \( Allowable\ Stress \) — Soil's allowable bearing capacity (lbs/sq ft)
• \( Area \) — Required footing area (sq ft)

Explanation: This formula calculates the minimum area needed to distribute the load safely over the soil without exceeding its bearing capacity.

3. Importance of Footing Size Calculation

Details: Proper footing sizing is essential for structural stability, preventing foundation failure, and ensuring uniform settlement distribution. It's a critical step in foundation design and construction.

4. Using the Calculator

Tips: Enter the total load in pounds and the allowable soil stress in pounds per square foot. Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What factors affect allowable soil stress?
A: Soil type, moisture content, depth of footing, and local building codes all influence allowable bearing capacity.

Q2: How do I determine the total load on a footing?
A: Total load includes dead loads (structure weight), live loads (occupancy loads), and environmental loads (snow, wind).

Q3: What is a typical allowable stress value for soil?
A: Values vary widely by soil type: 1500-4000 lbs/sq ft for sand, 1000-3000 lbs/sq ft for clay, but always consult a geotechnical engineer.

Q4: Should safety factors be applied to this calculation?
A: Yes, most building codes require applying safety factors to both loads and allowable stresses. Consult local building regulations.

Q5: Can this calculator be used for all foundation types?
A: This formula is primarily for spread footings. Other foundation types (pile, raft) require different calculation methods.