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How to Use Tubes to Fill Concrete Posts

By Kevin Ann Reinhart ; Updated September 21, 2017
A rented mixer makes filling concrete posts easier.

Concrete form tubes are made of high strength, water-resistant paper. They are designed to allow you to dig post holes and set your tubes and pour concrete into the forms all in one day. The durable tubes are of particular advantage in rainy weather when pouring concrete into an unsupported dirt hole would be ill advised. In locales that experience cold winter weather, concrete footings must extend at least 12 inches below the frost line, measure 8 inches thick or more and be twice as wide as the posts they will support. Using a tube to fill concrete posts helps you to meet required code without wasting concrete in the process.

Contact your local building inspector for information regarding the frost line in your area.

Measure your tube so that it will extend 12 inches or more deeper than the frost line. Remember also to allow for the height above grade that your post must be for your building project. Cut the tube to length using your hacksaw.

Drill your hole to the proper depth using your power auger, or dig it with a shovel. Remove the auger and set it well away from the hole.

Toss a 4-inch layer of gravel into the hole to aid drainage.

Insert the tube into the hole until it rests firmly on your gravel layer. Pack soil around the tube to keep it upright.

Mix your concrete mix with water according to package directions. A rented mixer or wheelbarrow, with a mixing drill or shovel to mix, will help you achieve the proper consistency.

Check for level and plumb of the tube and have an assistant hold the tube in place during the pouring process.

Pour the concrete into the tube. Use a piece of wood to mix the concrete every two feet or so until the tube is filled.

Apply water to the tubed footing to keep it damp for 48 hours while the concrete inside cures.

Backfill the hole with the remaining dirt and cut away the exposed paper tubing using your utility knife. Your footing is now complete.

 

Things You Will Need

  • Frost line depth information
  • Measuring tape
  • Power hole auger
  • Sawhorses; 2 or portable workbench
  • Hacksaw
  • Gravel
  • Level
  • Concrete mixer or wheelbarrow
  • Concrete mixing drill -- optional
  • Wood mixing stick
  • Utility knife

Tips

  • All tools and materials needed for this project are available for rental at your local home improvement store.
  • Post holes may be dug with a clamshell digger but a power augur is worth the rental cost if you have several footings to pour.

Warning

  • Keep children well away from power tools and post holes in order to maintain job site safety.

About the Author

 

Kevin Ann Reinhart, a retired teacher-librarian, has written professionally since 1976. Reinhart first published in "Writers' Undercover" Cambridge Writers Collective II. She has a bachelor's degree in English and religious studies from the University of Waterloo and a librarian specialist certificate from Queen's University and the University of Toronto.