Things You'll Need
Post hole digger
Fluted plastic footer base mold
Tube-shaped fiberglass footer mold
No. 4 steel rebar
Concrete pilings or piers are foundation elements that extend beneath the ground, and they anchor above-ground structures. Concrete pilings are most often used by homeowners in the construction of backyard decks and patios. Concrete is coupled with steel for reinforcement, and it is set deep enough to avoid freezing during winter months. Once set, pilings are built upon. The size and type of pilings used for a particular structure depend on the size and function of that structure.
Check with your local building authorities to find out how deep the frost line is in your area. The frost line must be accurately determined so your concrete pilings can be installed beneath the soil that may freeze. Freezing soil could cause the piling to crack, or cause it to move as the ground freezes and thaws.
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Dig a hole about twice the diameter of your concrete piling with your post hole digger and shovel. The hole should bottom out about 6 inches below the recognized frost line. Dig out the bottom of the hole to double the width of the top, and insert about 6 inches of gravel. Use your compactor to press the gravel down.
Attach a fluted plastic footer base mold to the bottom end of your tube-shaped fiberglass footer mold. The fluted base fans outward at its base and causes the weight carried by the piling to distribute over a wider area than a narrower form would. The rim of the tube should slide right over the top edge of the base and lock into position. Lower both forms into the hole.
Mix your concrete according to the manufacturer's instructions, and pour it into the mold. Fill the base of the mold and the bottom one-quarter of the tube. Use a piece of scrap stud to mix the concrete inside the mold so it settles properly. Repeat the process, filling one-quarter of the tube at a time. When you reach the top quarter of the tube, insert two to four lengths of No. 4 steel rebar. Lay a piece of scrap wood over the mouth of the tube, and use string to tie each piece of rebar so it is plumb and evenly spaced.
Drive each piece of rebar into the ground beneath your piling to a depth of about 6 inches with your hammer. Fill the tube the rest of the way, and allow the concrete to dry according to the manufacturer's instructions.
Install J-bolts or whatever anchoring hardware is required at the top end of the piling. Repeat the process wherever supports are needed.
Precast concrete pilings and piers are available at many building supply stores. These foundation elements come already assembled and need only to be placed into the ground for use.
Use caution when lifting heavy bags of concrete. Serious injury can occur if bags are lifted incorrectly.
Always wear work gloves when working with wet concrete. Concrete contains corrosive materials such as lime, which can cause skin irritation and other health issues. Inhaling concrete dust can damage your lungs.
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- Family Handyman: How to Build a Solid, Frost-Proof Deck Footing
- Home Time: Digging Footings & Pouring Concrete