Deck Footing Size Calculator
Deck
Span =
Cantilever =
Post Spacing =
Roof Overhang =
Loads
Dead Load = 10
Live Load = 40
Snow Load = 0
Soil Capacity = 1500
Tributary Area
Deck Area =
Roof Area =
Load
Deck =
Roof =
Total =
Square Footings
Dimension =
Thickness =
Round Footings
Diameter =
Depth =
sfdeck =
sfroof =
Help
Calculates the size of footings required for a covered deck with one side supported by a structure. This is based on the number of footings and posts supporting the deck, and the tributary area supported by each footing and post. It assumes a soil-bearing capacity of 1500 psf, the default capacity assumed in the 2009 IRC.
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Rows
Deck
-Span: Total span of the deck from where it rests on the ledger to its outside edge.
-Cantilever: Length of the cantilever beyond the post (if any).
-Post Spacing: On-center spacing of posts.
-Roof Overhang: Length of the overhang beyond the end of the deck.
Loads
-Dead Load: Weight / loads considered to act permanently; they are "dead," stationary, and not able to be removed.
-Live Load: Weight / loads produced by the use of the deck. Does not include elements such as snow.
-Snow Load: Probable amount of snow that will rest on the deck based on your geographical area.
-Soil Capacity: Bearing capacity of the soil. 2009 International Residential Code establishes the assumed bearing capacity is 1500 psf.
Tributary Area
-Deck Area: Area of deck to be supported by one footing and post.
-Roof Area: Area of roof to be supported by one footing and post.
Load
-Deck: Total weight per square foot of the DECK to be supported by one footing and post.
-Roof: Total weight per square foot of the ROOF to be supported by one footing and post.
-Total: Total weight per square foot of the DECK and ROOF (combined) to be supported by one footing and post.
Square Footings
-Dimension: Length and width of the square footing.
- Thickness: Depth of the footing.
Round Footings
-Diameter: Diameter of the round column.
-Depth: Depth of the footing.
Examples
Determine the footing size for a deck that measures 20 feet parallel to the house and is 14 feet deep. There is to be a 1 foot cantilever beyond the beam, which is 20 feet long. The posts are spaced 6 feet 8 inches apart. The deck is to be roofed with 1ft overhang, and each post and footing will share the combined loads of both the deck and the roof. The deck live load is 40 psf, and the design snow load is 30 psf.
Deck
-Span:14ft
-Cantilever: 1ft
-Post Spacing: 6ft 8in
-Roof Overhang: 1ft
Loads
-Dead Load: 10 psf
-Live Load: 40 psf
-Snow Load: 30 psf
-Soil Capacity: 1500 psf
The following results are calculated:
Tributary Area
-Deck Area: 50.00ft²
-Roof Area: 56.67ft²
Load
-Deck: 2500.00lb
-Roof: 2266.67lb
-Total: 4266.67lb
Square Footings
-Dimension: 1ft 9&3/8in
-Thickness: 10&11/16in
Round Footings
-Diameter 2ft 1/8in
-Depth: 1ft 1/16in
Keywords
Span
Cantilever
Post Spacing
Roof Overhang
Dead Load
Live Load
Snow Load
Soil Capacity
Deck Area
Roof Area
Deck
Roof
Total
Dimension
Thickness
Diameter
Depth
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