Concrete footings hold decks in place, preventing them from moving across your lawn, and they also support the weight of the deck. Before pouring deck footings, check with your building code officer to determine the required size and depth of the footings in your specific area. In cold climates, for example, footings must be deeper than in warm climates. This is due to frost line variations. Allow an afternoon or evening to dig and pour concrete footings.
Lay out the deck, and stake the footings every 4 feet. Pound stakes into the ground where you want the footings to be located. Make sure there is one on every corner.
Dig the holes for the deck posts, using a clamshell digger or power auger. Center the holes on the layout stakes.
Measure the hole depth according to your local building codes. Call your code enforcement officer for the specific codes in your area.
Pour 2 to 3 inches of loose gravel into the bottom of each footing hole. Loose gravel helps provide drainage under the concrete footings for the deck.
Cut concrete tube forms 2 inches longer than the hole depth, using a reciprocating saw. Repeat for each footing hole.
Insert the tubes into the footing holes, leaving approximately 2 inches of the tube above ground level. Verify that the tops of the tubes are level, using a carpenter's level.
Pack soil around the tubes to hold them in place, using your hands.
Mix and pour the concrete. Mix the concrete in a wheelbarrow, using a hoe and following the manufacturer's directions. Make sure the concrete is firm enough to hold its shape when sliced with a trowel.
Pour the concrete mixture slowly into the tube form. Guide the concrete into the tube form from the wheelbarrow, using a shovel. Tamp the concrete with a long stick to remove any air gaps.
Level the concrete in each tube form. Pull a 2-inch by 4-inch board across the top of the tube, using a sawing motion. Add concrete to any low areas, and repeat the leveling procedure.
Insert a J-bolt at an angle into the wet concrete at the center of each footing. Lower the J-bolt into the concrete slowly, wiggling it gently to prevent air gaps.
Set the J-bolt so it exposes ¾ inch to 1 inch above the concrete. Remove any wet concrete on the J-bolt by brushing it away with an old toothbrush. Use a plumb bob to verify that the J-bolt is positioned exactly in the center.
Plumb the J-bolt, using a torpedo level. If necessary, adjust the bolt until the torpedo level reads plumb, and repack the concrete. Allow the concrete to cure according to the manufacturer's directions.
Cut away the exposed portion of the tube, using a utility knife.