I need to know how deep to the footing and cement should be for my deck post. I'm replacing a post that supports my front stairs and 5x11 landing deck. The old post is 12 feet high. It's one of three posts supporting the landing etc. The others are in good shape, and shorter.

I expect to use a concrete tube form in the footing, but also don't know how deep the cement should be. 2 feet, 3 feet, 4 feet?

In the top of the cement form I'll insert a Simpson Strong-Tie CB Galvanized Column Base for 4x4 Nominal Lumber Model #CB44.

I would place gravel in the bottom of the hole under the cement, though also not sure how much gravel...a foot?

The frost depth where I live is 12 inches minimum.

Thanks Mike

1 Answer 1


You need to check the building codes for where you live. If you go to your cities website they may have it on there or you could call the local inspector. I live in Minnesota and I believe the depth has to be 48 inches.

  • 1
    Yes, your city or county permitting agency will often have a "deck building" pamphlet that shows you exactly what you need to do for support, and framing/spans.
    – Huesmann
    Jun 14, 2023 at 15:26
  • 1
    Ok. Appreciate it. I didn't want to involve the city. The deck has lasted 27 years, so I thought what was done then was good enough for another 20-30 years.
    – Mike M
    Jun 14, 2023 at 19:43

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