Set pier diameter, depth and height above grade. You get concrete and how many 12 foot tubes to bring home.
How it works
Each tube holds 3.14 × radius squared × length. Tubes are counted from how many pier lengths fit in 12 feet, with 5% extra concrete.
Before you order
- Cut the tube a little long so you can screed the top level on site.
- Backfill and tamp around the tube before pouring so it cannot float or shift.
- Keep cardboard form above grade only as long as you plan to, and peel it after the concrete cures.
Common questions
How many bags fill a 12 inch tube?
About 0.785 cubic feet per foot of height, which is roughly 1.3 of the 80 lb bags per foot.
Can form tubes go below the frost line?
Yes. Set the tube depth by your frost depth and local footing rules.