Loading

Create a free account and get instant & exclusive access to all that Decks.com has to offer:

Checkmark 1,000+ How-To articles
Checkmark 80+ Free Deck Plans
Checkmark Deck Planning Calculators
Checkmark Free & Simple Deck Design Tool

Deck Footing Size Chart

In order to determine the proper size for your footings, you will need to establish how much total weight they are going to have to support and what kind of soil they are covering. To calculate the load, you should use 40lbs per square foot for live loads (these are variable loads that are dynamic such as the weight of people and furniture) and 15 lbs per square foot for dead loads (this is the weight of the materials used for the construction of the deck) for a total load weight of 55 lbs per square foot.


For example, if you are building a 10x10 deck attached to a house with two footings on the corners, you could calculate the loads for the footings in the following way. First, draw a line dividing the deck into two halves between the house and the footings. The load for the section nearest the house will be transferred back to the ledger board and carried down to the house foundation. The remaining half of the deck will again be split into two parts to be supported by the two corner footings. This is called the tributary load.  If you multiply the area of this section 5’ x 5’, you will get 25 square feet. You can multiply this area by 55 lbs per square foot loading to come up with 1,375 lbs total load. Once you know the total load, you can use the chart below to determine the footing size for your soil conditions. Always be sure to check your calculations with your local building inspections department before digging.

Show Load Deck
PinterestSave

 

 

Circular Footings

Maximum Allowable Load Per Footing, in Lbs

Soil Type GravelSandClay
Allowable Pressure (Lbs /Sq Ft) 300020001500
Footing Size (inches)12230015001100
 13270018001300
 14320021001600
 15360024001800
 16410027002000
 17470031002300
 18530035002600
 19590039002900
 20650043003200
 21720048003600
 22790052003900
 23860057004300
 24940062004700

Popular Footings Articles
Concrete

Cutting a Concrete Pad

Learn how to use a concrete saw to cut a hole in a patio slab to install a deck footing.

Footing Installation

Installing footings on a sloped yard

Our inspector explains how to install concrete deck footings on uneven ground.

Footing Installation

Water in deck footing holes

Find out what to do if your deck footing holes fill up with water.

Next Step: Framing Articles
Deck Support Columns

How to Decorate Deck Support Columns

Browse some examples of decorative deck support posts for tall decks.

Deck Framing

Reinforcing Deck Rim or Band Joists

Learn a technique to strengthen your guard rails by installing a double rim joist and adding structural blocking to reduce bounce.

Deck Framing

Building A Deck Over An Air Conditioner

Things to consider when building a deck near an air conditioning unit. You may want to relocate the AC unit if possible to avoid some problems.

Get more helpful resources delivered right to your inbox

Explore Articles by Topic

Create a free account and get instant & exclusive access to all that Decks.com has to offer:

Checkmark 1,000+ How-To articles
Checkmark 80+ Free Deck Plans
Checkmark Deck Planning Calculators
Checkmark Free & Simple Deck Design Tool
Footing Installation

Deck Footing Size Chart

In order to determine the proper size for your footings, you will need to establish how much total weight they are going to have to support and what kind of soil they are covering. To calculate the load, you should use 40lbs per square foot for live loads (these are variable loads that are dynamic such as the weight of people and furniture) and 15 lbs per square foot for dead loads (this is the weight of the materials used for the construction of the deck) for a total load weight of 55 lbs per square foot.


For example, if you are building a 10x10 deck attached to a house with two footings on the corners, you could calculate the loads for the footings in the following way. First, draw a line dividing the deck into two halves between the house and the footings. The load for the section nearest the house will be transferred back to the ledger board and carried down to the house foundation. The remaining half of the deck will again be split into two parts to be supported by the two corner footings. This is called the tributary load.  If you multiply the area of this section 5’ x 5’, you will get 25 square feet. You can multiply this area by 55 lbs per square foot loading to come up with 1,375 lbs total load. Once you know the total load, you can use the chart below to determine the footing size for your soil conditions. Always be sure to check your calculations with your local building inspections department before digging.

PinterestSave

 

 

Circular Footings

Maximum Allowable Load Per Footing, in Lbs

Soil Type   Gravel Sand Clay
Allowable Pressure (Lbs /Sq Ft)   3000 2000 1500
Footing Size (inches) 12 2300 1500 1100
  13 2700 1800 1300
  14 3200 2100 1600
  15 3600 2400 1800
  16 4100 2700 2000
  17 4700 3100 2300
  18 5300 3500 2600
  19 5900 3900 2900
  20 6500 4300 3200
  21 7200 4800 3600
  22 7900 5200 3900
  23 8600 5700 4300
  24 9400 6200 4700

Popular Footings Articles
Concrete

Cutting a Concrete Pad

Learn how to use a concrete saw to cut a hole in a patio slab to install a deck footing.

Footing Types

Monolithic Pier

Compare the pros and cons of installing a solid concrete deck footing using a cardboard tube or engineered forms.

Concrete

Foundation Washout

Steep hills and loose soil can be a recipe for disaster for deck footings. Consider some of our tips to help prevent your footings from washing away.

Next Step: Framing Articles
Deck Support Columns

How to Decorate Deck Support Columns

Browse some examples of decorative deck support posts for tall decks.

Deck Support Beams

Beam Span Chart

Learn how to size your deck beam using this easy-to-use span table. Just cross-reference the post spacing and joist length to determine the beam size.

Deck Framing

How to Angle Corners and Joists

Learn how to frame a deck with angled or clipped 45-degree corners using a cantilever beam.

Get more helpful resources delivered right to your inbox

Explore Articles by Topic