Once the hole is dug it is time to install the concrete footings. Footings are the concrete and steel support that hold the home and keep it from sinking or shifting on the earth. The footings in the above picture on the inside of the home will hold bearing walls that support the framed floor.
The first step is to layout the home corners in the bottom of the hole. This can be done by the contractor or a surveyor. A wood or steel pin is put at each corner of the new house. The location of these pins needs to be exact. The footing contractor then installs a string to the pins and measures from each pin and installs form boards that will hold the concrete.
After the boards are up then steel rebar is installed to give strength to the concrete. The rebar cannot touch the ground so it is held in the air by wires or special trays. To make the top of the footings perfectly level a laser level and chalk line or nails are used to mark the inside of the form boards so the workers know where to fill the forms to.
The concrete is often placed in the forms by using a concrete pump. The workers walk around with the hose and fill up the forms. After the forms are filled to the level mark the top of the concrete is smoothed off.
The final step is to install pieces of rebar vertically into the concrete. These vertical rebar will connect to the rebar in the foundation wall. The size of the footings and amount of rebar are specified by a structural engineer during the planning stage. Sizes vary depending on soil conditions, size of the house and geographical region.
In this image you can see the corner pin which is the location of the very corner of the house. A string line is used to indicate the outside of the future concrete wall so the vertical rebar can be placed properly. Every home must have a grounding rod attached to the steel in the foundation.
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