A well-designed deck requires properly spaced footings to ensure structural stability and safety. The Deck Footing Calculator is a simple tool that determines the number of footings needed based on the deck's dimensions, footing spacing, and beam spacing.

What Does the Deck Footing Calculator Do?

The calculator determines the total number of footings needed for a deck by considering:

1. The length and width of the deck.
2. The spacing of footings along the length.
3. The spacing of beams along the width.

Formulas Used in the Calculator

1. Footings Along the Length of the Deck

The number of footings required along the length of the deck is calculated using:

$\text{Footings Along Length} = \lceil \frac{\text{Deck Length}}{\text{Footing Spacing}} \rceil + 1$

Where:

• Deck Length: Total horizontal length of the deck.
• Footing Spacing: Distance between two consecutive footings along the length.
• ⌈x⌉: Ceiling function, which rounds up to the nearest whole number.

2. Footings Along the Width of the Deck

The number of footings required along the width of the deck is calculated using:

$\text{Footings Along Width} = \lceil \frac{\text{Deck Width}}{\text{Beam Spacing}} \rceil + 1$

Where:

• Deck Width: Total horizontal width of the deck.
• Beam Spacing: Distance between two consecutive beams.

3. Total Number of Footings

The total number of footings is the product of the footings along the length and width:

$\text{Total Footings} = \text{Footings Along Length} \times \text{Footings Along Width}$

Where:

• Footings Along Length: Number of footings required along the deck's length.
• Footings Along Width: Number of footings required along the deck's width.

Example Calculation

Inputs:

• Deck Length (L): 20 ft
• Deck Width (W): 10 ft
• Footing Spacing (FS): 6 ft
• Beam Spacing (BS): 8 ft

Step 1: Calculate Footings Along Length

Using the formula:

$\text{Footings Along Length} = \lceil \frac{\text{Deck Length}}{\text{Footing Spacing}} \rceil + 1$

Substitute the values:

$\text{Footings Along Length} = \lceil \frac{20}{6} \rceil + 1 = \lceil 3.33 \rceil + 1 = 4 + 1 = 5$

Step 2: Calculate Footings Along Width

Using the formula:

$\text{Footings Along Width} = \lceil \frac{\text{Deck Width}}{\text{Beam Spacing}} \rceil + 1$

Substitute the values:

$\text{Footings Along Width} = \lceil \frac{10}{8} \rceil + 1 = \lceil 1.25 \rceil + 1 = 2 + 1 = 3$

Step 3: Calculate Total Footings

Using the formula:

$\text{Total Footings} = \text{Footings Along Length} \times \text{Footings Along Width}$

Substitute the values:

$\text{Total Footings} = 5 \times 3 = 15$

Conclusion

The Deck Footing Calculator simplifies the process of determining the number of footings needed for a deck. By inputting your deck's dimensions, footing spacing, and beam spacing, you can accurately estimate the required footings and ensure proper support for your structure. Proper footing placement ensures a stable and durable deck, making it a crucial step in your construction project.

FAQ

1.What is a deck footing and why is it important?

• What it is: A deck footing is a concrete base that supports the deck posts, transferring the weight of the deck, railings, and occupants to the ground.
• Why it's important: Footings are crucial for the safety and stability of your deck. They prevent the posts from sinking into the ground, which can cause uneven decking, safety hazards, and even structural failure.

2. What factors determine the size of a deck footing?

• Post Load: The total weight the post will support (deck weight, railing weight, live load).
• Soil Bearing Capacity: The ability of the soil to withstand pressure without settling. This varies greatly depending on soil type (clay, sand, etc.).
• Safety Factor: A safety margin to account for uncertainties in soil conditions and loading.

3. How deep should deck footings be?

• Frost Line: Footings must be placed below the frost line to prevent them from being lifted by freezing and thawing of the ground. The frost line depth varies depending on your location.
• Local Codes: Always check local building codes for specific requirements regarding footing depth.