Enter all but one of the width, length, depth, soil bearing capacity, allowable soil bearing capacity, and safety factor into the calculator to determine the size of the deck footing.
Deck Footing Formula
The following formula is used to calculate the size of a deck footing:
F = (W * L * D * C) / (S * B)
Variables:
- F is the size of the deck footing
- W is the width of the deck
- L is the length of the deck
- D is the depth of the deck footing
- C is the soil bearing capacity
- S is the allowable soil bearing capacity
- B is the safety factor
To calculate the size of the deck footing, multiply the width, length, depth, and soil bearing capacity of the deck. Divide the result by the allowable soil bearing capacity multiplied by the safety factor.
What is a Deck Footing?
A deck footing is a crucial structural element that provides the foundation for a deck. It is typically made of concrete and is buried into the ground, acting as a base for the deck’s support posts. The footing is designed to distribute the weight of the deck and prevent it from sinking or shifting, which could lead to structural instability. The size and depth of the footing depend on the size and weight of the deck, the type of soil, and local building codes. It is essential to install the footing correctly to ensure the longevity and safety of the deck.
How to Calculate Deck Footing?
The following steps outline how to calculate the Deck Footing.
- First, determine the length of the deck (in feet).
- Next, determine the width of the deck (in feet).
- Next, calculate the area of the deck by multiplying the length and width (Area = Length x Width).
- Next, determine the depth of the footing (in feet).
- Next, calculate the volume of the footing by multiplying the area of the deck and the depth of the footing (Volume = Area x Depth).
- Finally, calculate the amount of concrete needed for the footing by dividing the volume of the footing by the volume of one bag of concrete (Amount of Concrete = Volume of Footing / Volume of One Bag of Concrete).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Length of the deck (in feet) = 12
Width of the deck (in feet) = 8
Depth of the footing (in feet) = 2
