How to Prepare a Shed Base

Dig a rectangle slightly larger than the size of the shed you plan to build. Go at least four inches deep so that any grass comes away at the root. Remove any extra organic material like sticks and roots.

Tamp the soil with a soil tamper available at your local hardware or big box store. Get a long-handled tamper with a base that’s at least 10 pounds. Pound the soil with the tamper throughout the rectangle to compress the dirt and prepare it for the gravel layer.

Cut a sheet of weed mat to size and cover the tamped soil with it. Use the included spikes to hold it down. If you need to lay several strips to cover the area, make sure they overlap rather than butt against each other. Weeds will come through the seams if you don’t overlap.

Put down a layer of gravel. Ask your masonry shop or hardware store for “crusher run” gravel. This is a small-grade gravel that includes gravel dust. Lay about 4 inches and smooth it out.

Put a four-inch concrete block at the corners. Solid block is best as building block with holes can trap moisture. Level each stone.

Lay a straight two by four across the expanse between two corner stones and use the four foot to bring them in line. If you are building on a grade, use as many two inch blocks as necessary to bring the lowest point up to the level of the other corners. Fine tune the balance by using an asphalt shingle as a shim until you get a perfect reading on the level.

Lay your two by four across the expanse to the other adjacent corner stone (not the diagonal). You want to level in two directions. When you’ve gotten good readings in both directions, do the same thing from the corner opposite the one you’ve measured and level it in both directions. If all readings come up level, there is no need to level the diagonals with each other. The foundation is ready for your shed floor.