I cemented my mailbox to hold it steady but the cement cracked and now it is wobbly. Does anyone know why that happened? I probably need to dig the concrete out and replace it with new concrete and gravel. I didn't put in gravel the first time. But,of course,I am looking for an easier way. I need to shore it up. Any ideas?

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    You haven't told us enough about the project to expect reliable answers. Depth, width, pole size, concrete mix, water ratio, etc. are all relevant. Please edit to help us help you. – isherwood Aug 1 '17 at 18:07
  • simple answer: concrete cracks. FYI, you can now get an expanding foam product for setting fence posts that might work perfectly for this task. – DA01 Aug 1 '17 at 18:25

To determine why the footing broke some more information on the footing such as hole depth, diameter, climate as well as what your cement mix was would be helpful.

My best guess as to why the cement cracked would be that it was not mixed correctly, or simply not enough cement to hold the mail box.

I would not recommend trying to shore it up, in my experience that is always more trouble than it is worth. Your best bet is likely to dig it out and put in new concrete. You said you are looking for a simply solution so take a look at Quikrete or something similar depending on where you are and what you can get. The premixed Quikrete stuff is dead easy just add water and fill the hole.

I like to overbuild so I would make sure the hole is 3+ feet deep, minimum 8 inches diameter and I would set a 4x4 to hold the mail box.

  • An 8" round hole around a 4x4 leaves barely 2" of concrete. That's not nearly enough to prevent stress cracking. I'd want the top portion of the base to be at least twice that thickness around the post. – isherwood Aug 1 '17 at 18:08

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