Footings

May 16th, 2010 by KTU | Filed under 2. The Site, Excavation, and Foundation.

Footings are the roughly one-foot thick slabs of concrete on which the foundation walls of the house rest. They are designed to be large enough to distribute the weight of the house onto the excavated soil surface such that the soil does not collapse from the load. As a practical matter they tend to be 20-72 inches wide depending on what part of the house they support. They usually need to be 24-48 inches below the ground surface (depending on region) to be below the frost line.

Placing the footings is a pretty remarkable thing to watch. A crew of 8 (Stone Construction) arrived at 7am and they left around 6pm. With another two hours of work the next morning to strip the forms and pack up, I had completed footings.

This not a fussy construction task. They take a trailer full of lumber and hammer it together in the rough shape they’re after. They pump the forms full of concrete, and then trowel the top surface to a snapped line, which defines the top surface of the footing. The foundation walls are then built on top of these troweled surfaces. The photos tell the story.

The excavated site. The excavator gets the surfaces at the right elevation and the surveyor pounds bars where the foundation wall corners are supposed to be.

Assembling the forms.

More assembly. Code requires that footings be continuous, so when the elevation changes, the footing goes vertical.

The excavator overshot the lower level excavating a bit, so they had to build a 6 ft x 6 ft x 6 ft form to create the required footing surface at the higher level.

Forms with rebar installed and steel clips applied across top to hold forms together. The building inspector has to sign off at this point before they can pour.

Lonnie, the foundation contractor (left), with Larry, the pump truck guy.

The pump truck has a huge boom to get a 6 inch rubber hose to deliver the concrete at the right location. We used 6 trucks worth of mud...see them lined up.

The concrete truck delivers the mud to the pump truck.

Shooting the mud (at an incredible rate). You want to know what you are doing when the mud is flowing this fast.

Filling that 6 ft. cube.

Pretty much finished placing the concrete in the forms. The rebar is stuck in after the pour and will be tied into the foundation wall.

The finished footings just after the forms were stripped the next morning.

Happy homeowner sitting on a 6 foot cube of concrete.


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