1. What is a Deck Footing Size Calculator?

Definition: This calculator determines the required footing size for a deck based on the total load and soil bearing capacity.

Purpose: It helps ensure deck footings are properly sized to support the structure without settling or failing.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Size \) — Required footing area (square feet)
• \( Load \) — Total load on the footing (pounds)
• \( Soil\ Bearing\ Capacity \) — Soil's load-bearing capacity (pounds per square foot)

Explanation: The total load is divided by the soil's bearing capacity to determine the minimum footing area needed to safely distribute the load.

3. Importance of Proper Footing Sizing

Details: Correct footing size prevents deck settlement, ensures structural integrity, and complies with building codes. Undersized footings can lead to deck failure.

4. Using the Calculator

Tips: Enter the total load in pounds and soil bearing capacity (default 1500 lb/sq ft for typical residential soil). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine the total load on my footing?
A: Sum the dead load (deck weight) and live load (people, furniture). A typical deck has 50 psf live load + 10 psf dead load.

Q2: What's a typical soil bearing capacity?
A: Varies by soil type: 1500 lb/sq ft (clay), 2000 lb/sq ft (sand), 3000 lb/sq ft (gravel). Consult a geotechnical engineer for exact values.

Q3: How does frost depth affect footing size?
A: Frost depth determines footing depth, not area. Footings must extend below frost line to prevent heaving.

Q4: Should I round up the calculated size?
A: Yes, always round up to the nearest standard footing size for safety.

Q5: How many footings does my deck need?
A: Divide total deck load by number of footings to get load per footing, then calculate each footing size.