Concrete footings are essentially tubes of concrete that you pour deep into the ground to act as individual foundations for each post or leg for a porch, deck or patio. These footings increase structural integrity by giving each post a strong base that won't shift drastically every time the ground freezes. This will help keep the porch level, which will make it last longer than if you were to just build directly on the ground or a simple concrete slab.
Things You'll Need
- Measuring tape
- Stakes or flags
- Clamshell digger
- Concrete form tubes
- 2-by-4 planks
- Dry concrete mix
- Long pole
- Post bases
Check the plans for your porch to see how many footings you will need. Mark the location for each footer you will need to dig by driving a stake or flag into the ground.
Consult your local building inspector for footing requirements in your area based on your project. The basic rule is that the footing needs to extend about 12 inches below the frost line. However, frost lines vary depending on region, so the total depth of holes is wholly dependent on your local building codes.
Dig flared holes with a clamshell digger to the depth specified by the building inspector. Insert a concrete form tube into the hole so that the bottom of the tube is about 12 inches above the bottom of the hole and the top of the tube extends at least 2 inches from the top of the hole.
Instruct someone to hold the form tube in place while you build a square support frame around the tube, using four pieces of 2-by-4 inch lumber. Secure the frame to the tube with nails to keep the tube from slipping into the ground.
Mix dry concrete with water in a wheelbarrow until it reaches a pourable consistency. Stir the concrete with a spade. See the concrete packaging for specific information on dry mix-to-water ratios for your product.
Pour the mixed concrete into the hole slowly until the area below the tube is filled, plus an additional 2 feet or so. Slide a large pole, dowel or broomstick down into the hole and mix the concrete vigorously to drive out any air pockets and help the wet mixture settle into the hole.
Continue pouring concrete in 2-foot sections and agitating the mixture with the pole until the form tube is completely full. Drag a length of 2-by-4 across the top of the tube to level the concrete.
Slide lengths of rebar into the concrete if you were instructed to do so by the building inspector. The rebar must extend to the bottom of the hole. If there are post bases included in your porch design, insert them while the concrete is still wet.
Allow the concrete to cure for two days before resuming construction of your porch. Spray the footing with water occasionally to prevent the concrete from drying too quickly, which can cause cracking.
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