How to Pour a Footer for a Concrete Block Wall
A well-done footer creates a firm foundation for a long-lasting concrete block wall. The standard width of a footer is twice the width of the concrete block chosen for the wall. The standard height, or depth, is the width of the concrete block being used for the wall. A footer is poured 6 inches below the frost line on a 6-inch bed of gravel for drainage. The total depth of the area for the footer is the depth of the frost line plus the width of the concrete block being used for the concrete block wall plus 6 inches for a gravel base. Does this Spark an idea?
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Things You'll Need
- Shovel
- Square Shovel
- Lumber
- Saw
- Drill with Screwdriver Bit
- Screws
- Tamper
- Gravel
- Level
- Rebar
- Concrete
- Concrete Mixing Trough or Wheelbarrow Water
- Screed Board
Instructions
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Call 811, a federally-mandated number which was designed to prevent unintentional hitting of underground utility lines, such as electric and gas lines, before digging.
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Understand the law before digging. The Common Ground Alliance is a continuation of the United States Department of Transportation initiative to create one organization for keeping all underground utility information current. The Common Ground Alliance website has additional state-specific contact information to help prevent unintentional hitting of underground utility lines. By federal law, you are responsible for checking the location of underground utility lines before starting any digging project. The law was written to prevent the disruption of utility service from preventable digging accidents. If a utility line is damaged while digging, you may be fined and responsible for repairs to the utility lines.
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Dig the footer area twice the width of the block being used for the wall. The depth required is the depth of the frost line plus the width of the block being used for the wall plus 6 inches added for crushed stone or gravel. Use a square shovel to keep the edges straight. If the soil is firm enough to use as the concrete form, dig a shelf that is 2-inches wide by 4-inches deep on both sides of the trench to set the screed rails. If the soil is loose, dig an additional 2 inches on each side so a wooden form can be placed in the trench. Use a tamper to compact the soil at the bottom of the hole.
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Fill with 6 inches of gravel or crushed stone. Use a level to level the stone.
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Screw a stake onto each 2-by-4 lumber needed for both sides of the hole. If the sides of the hole for the footer are sturdy enough to use as a form, create screed rails by using stakes and 2-by-4 lumber. Lay the 2-by-4 lumber in the rail shelf created while digging, so the stakes are on the outside and the inner edge of the 2-by-4 is twice the distance of the concrete block chosen for the wall. Level the 2-by-4s in the hole. Use the level on the rails across the trench to be sure they are level with each other.
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Create forms if the sides of the trench are too soft and will not maintain a wall to pour the concrete against. Cut plywood to the height needed, the same height as the concrete block being used for the project. Line both sides of the hole with the plywood sections screwed to stakes. The top of each section of plywood should be 6 inches below the frost line. Level the forms the length of the trench. Use the level on the form tops across the trench to be sure the forms are level with each other.
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Spray the forms or screed rails with concrete release or clean motor oil so they can be removed easily.
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Lay rebar 1/3 up from the bottom of the footer. Use small blocks of 2-by-4 to lift the rebar off the gravel. Do not lay full pieces, just use a few blocks, say 3 or 4, on each length of rebar to raise the rebar to the appropriate height.
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Mix the concrete according to package directions. Starting at one end, pour the concrete into the trench. Use 2-by-4 lumber and cut the area 6 inches wider than the hole to screed the concrete. To screed concrete, simply lay the screed wood across the screed rails or form tops and level the concrete in the trench. Fill shallow sections that the screed board cannot push. The goal is to use the board to make the top of the concrete perfectly level in between the screed rails or form tops.
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Cover the footer with heavy plastic. Allow the concrete to cure for 3 to 4 days before removing the screed rails or forms and beginning the concrete block wall.
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Tips & Warnings
Clean all the concrete tools as soon as possible to make them easier to clean.
Some municipalities have requirements for pouring concrete footers and building concrete walls. Check with your local municipality for more information.
