Column footing as a trench footing

[JoeBaseplate]

Has anyone ever done a column footing in form of a trench footing rather then a formed one? The question has come up on a project where due to time constraints the contractor wants to do trench footings at walls. That should be OK, I have done that before. But now they are wondering if they can do something similar with the 5’x5’ column footings. I guess technically it should work, you still have the same rebar, the same area………but am I missing something?

 

[hokie66]

I have rarely seen footings formed, except by the earth. Sandy soils require forming, but in cohesive conditions, the norm is to pour against the earth. Sometimes working mats are required, especially in rainy weather.

 

[JoeBaseplate]

Hokie,

So I guess in the attached sketch, I can replace the pier and footing with one pour then?

 

[BAretired]

You could, but that would require considerably more concrete. If the contractor prefers a single pour, okay but otherwise stick to the footing and pedestal.

BA

 

[hokie66]

Well, yes, but that's not how I understood your original question. It looks like you didn't intend to form the footing...just the pier.

 

[Teguci]

If you form against earth remember to increase your cover to 3" on the sides. As for getting rid of the pier, absolutely! Why would you form and reinforce all of that.

 

[hokie66]

There are arguments both ways. One reason for building the pedestal is that you get a better chance of having the anchor bolts in the right position.

 

[hokie66]

Another option which many contractors prefer is to move the actual footing up, and fill the hole with low strength concrete to the bottom of the footing.