I'm building a 10x10 shed and planning to use concrete blocks from Home Depot as the foundation. I want to use 9 blocks—4 at the corners, 4 in the middle of the edges, and 1 in the center. Before I proceed, I'm wondering if each block needs a gravel foundation underneath. I've seen videos where rock is used and others where it isn't. If gravel is necessary, I'm thinking of digging a recess for the blocks about 6-7 inches deep, filling it with 3-4 inches of all-purpose gravel, and then placing the blocks on top. I'd love to know if that's a good plan or if there's something better than all-purpose gravel. I heard limestone is good, but it's not available at Home Depot. Also, I'm on a budget and need this done quickly since I have upcoming events. This shed should last around 3-5 years until I can invest in a better one. One more thing, do I need to seal the concrete blocks with acrylic cure and sealer?
5 Answers
For a solid and stable base, I'd recommend using crushed stone like granite or limestone, or dense graded aggregate (DGA). They compact well and lock together, which gives you that stability you need. I usually get mine from a local quarry when I need it.
The key is having a base that stays solid and doesn’t shift. You want to avoid organic material that can decompose. Tamped gravel works great for this. Just keep in mind the frost lines in your area could also affect your foundation, so choose your material carefully.
Yeah, using the framed floor adds strength! Just ensure those blocks are stable, and you should be good. But definitely don’t put them directly on grass.
If your ground is level and solid, you might not need a gravel foundation—but if it’s uneven or soft, you’ll want something to support those blocks. I suggest digging a 16x16 inch hole that's at least 10 inches deep, filling it with gravel, and laying a patio stone on top for added support before placing your deck blocks. This might cost you around $80 for a solid base setup.
If you're in a rush and on a budget, maybe it's worth just storing your lawn equipment in the garage until you have time and resources to set up a proper foundation later. This could save you a headache in the long run!
You also need to consider the weather in your area. Different climates can affect how well your foundation holds up, so make sure to factor that in before you dive in.
Got it! I know the ground is pretty level where I'm putting it, and I’m getting a framed wood floor, so I think that will work for the middle part. Do you think 9 blocks will hold up, even if it's light stuff? I don't want it to cave in!