# 10' x 20' STEEL CANTILEVER PERGOLA FOOTING SIZE



## SPS-1 (Oct 21, 2008)

ForeignerDIYer said:


> I was going to do 40"x 35" x 26" deep for the large posts .....


So the post is buried in the footing (not bolted on top) ? Your size does not look too far out of whack. Is the footing offset towards the cantilever side ? Have you figured out where the center of gravity is ? I am not sure what is necessary, but it would be nice to have the footing extend (horizontally) to center of gravity of the structure. 

Where are you located? Is 26" below the frost line ?


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## Nealtw (Jun 22, 2017)

I would think the footing is 5 or 6 ft wide and when that is not enough , you design a concrete bench to help weigh it down.


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## ForeignerDIYer (Dec 13, 2020)

SPS-1 said:


> So the post is buried in the footing (not bolted on top) ? Your size does not look too far out of whack. Is the footing offset towards the cantilever side ? Have you figured out where the center of gravity is ? I am not sure what is necessary, but it would be nice to have the footing extend (horizontally) to center of gravity of the structure.
> 
> Where are you located? Is 26" below the frost line ?


Yes the post will be buried down 2 feet into the footing. The two large post footings are basically a square so I am sure it doesn’t extend to the center of gravity. The 3 smaller ones in the middle do extend a bit further towards the cantilever. If the footings for the seating area are going to be within the center of the gravity and they connect with the structure footing is that enough even though the footing for the seating area will be around 4 inches? No frost line to worry about in Phoenix, Az.


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## ForeignerDIYer (Dec 13, 2020)

Nealtw said:


> I would think the footing is 5 or 6 ft wide and when that is not enough , you design a concrete bench to help weigh it down.


Does it need to be 26” deep all the way or can I do the initial 40” at that depth 26” and then say go down 12” deep the rest of the way?


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## Nealtw (Jun 22, 2017)

ForeignerDIYer said:


> Does it need to be 26” deep all the way or can I do the initial 40” at that depth 26” and then say go down 12” deep the rest of the way?


I have no experience with this but when we do retaining walls the footing is wide to spread the load on the soil and the connection is strong with rebar to resist the bending moment at the base.
I would want an engineer to design the footing


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