A foundation footing is a wide shallow pad that supports the foundation wall and distributes the weight of the structure above into the surrounding ground. Most foundations have footings unless they are simple slab-on-grade foundations constructed in a single pour. Blueprints and local building codes determine the specifications for the footing. Before digging, get a permit from your local building authority and call local utility companies to make sure no buried lines are in the way.
Things You'll Need
- Tape measure
- Dimensional lumber
- String line
- Screw gun
- Wood screws
- Steel rebar rods
- Rebar ties
- Rebar pigtail tool
- Rebar bender/cutter
Dig the trenches, which lie beneath load-bearing walls, with a backhoe. These include the exterior walls and potentially one or more interior load-bearing walls, indicated on the blueprints, that require a poured footing. Dig the footing trenches only to the depth of the footing. Do not disturb the soil any deeper.
Drive stakes to indicate the inside and outside corners of the footing and run a string line between the stakes to provide a visual guide for installing the footing forms. You’ll need one line to indicate the outside edge of the footing and another line to indicate the inside edge.
Cut dimensional lumber to form the sides of the footing. The size of the lumber depends upon the required footing height. If the footing will be eight inches high, use 1-by-8 boards. If the footing must be a foot high, use 1-by-12s.
Drive support stakes to hold the footing forms in place. Position the stakes on the outside of the form boards every couple of feet.
Attach the form boards to the insides of the stakes with wood screws and screw gun. Use a level to keep the top edge of the boards even with the top of the future footing height.
Add steel reinforcement inside the forms. The amount of steel you add must comply with local building codes. Use a rebar bender/cutter and install the steel rods both widthwise and lengthwise in the footing forms.
Secure the bars where they cross with rebar ties.
Call the building inspector to examine the forms and the steel reinforcement before you pour the concrete.
Have a minimum of three knowledgeable concrete workers on site when the concrete truck arrives. One worker will direct the truck driver and the concrete chute during the pour. The other two will spread and smooth the concrete.
Start the pour on an exterior footing wall and pour continuously.
Shovel and distribute the wet concrete into the form, leveling it with the top of the form boards as you go. The top need not be pretty, but it should be level. By placing a 2-by-4 across the top of the forms and pulling it along the top of the forms, you can level the wet concrete.
Insert vertical rebar rods into the center of the footing when the concrete hardens enough to support the rods. These rods secure the foundation walls to the footings. Local code determines how far apart the rods must be, but the standard is 12 to 16 inches apart.
Strip the footing forms the follow day.
Tips & Warnings
- The simplest way to use rebar ties is to slip a tie, which is a piece of wire about 6 inches long with a loop on each end, under the “X” where the bars intersect and bring the looped ends together on top. Stick the tip of a rebar pigtail tool into both loops and give the tool a firm twist to quickly wind the ties around the bars.
- Work quickly on a hot day; concrete can begin to set within an hour.
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