I have a concrete slab in my backyard that I'm not sure about its original purpose. I want to build a storage shed for my lawn tools around this slab, using 4x4s for the corners. My goal is to have the shed walls be 8 feet high. Can anyone advise me on how deep I should bury the 4x4s into the ground for proper stability?
5 Answers
Typically, it’s better to build directly on top of the existing slab instead of next to it. Any reason you’re thinking about placing the walls nearby instead of right on the concrete?
There's a general rule that says to bury a post about 10% of its length plus 2 feet. But definitely pay attention to the frost line in your area to ensure your shed is stable over the long haul.
Don’t forget to check your local zoning laws! Usually, footings must go below the frost line to be compliant. Better to be safe and do it right the first time!
Instead of burying the posts directly in the cement, consider using brackets to keep them about an inch above the concrete to prevent rot. You need a solid foundation to avoid issues like settling or structural failure, especially given the weight of a storage shed. Plus, ensure your cement base is wide enough for the load.
The depth really varies based on your location. You should dig below the frost line, which is about 30 inches in my area. That's ideal, but if you're looking for a minimum depth, going down at least two feet should be stable. For 8-foot walls, consider getting 10-foot 4x4s to accommodate that. Just make sure to check what your frost line is though!
I just thought I might save some concrete, but I see your point.