How to Pour a Slab for a Yard Shed

Mark the location of the shed by driving stakes into the ground around the perimeter or by marking it with spray paint.

Excavate the area inside the stakes or paint. Go beneath the frost line when digging (your local zoning board can provide you with the depth of the frost line in your area).

Build a frame for the concrete by driving wooden stakes into the ground around the perimeter and nailing 2-by-4 boards to them.

Cover the soil inside the pit with a vapor barrier. This is a plastic sheet that protects the foundation from moisture seeping up and damaging it.

Cover the vapor barrier with sand or gravel. Follow local building codes regarding which material to use and how deep the layer needs to be.

Place rebar or wire mesh on top of the sand or gravel. This helps strengthen the concrete. Again, follow local building codes regarding which material to use.

Mix a batch of concrete. Follow the instructions on the packaging, as it can vary by manufacturer.

Fill the pit with concrete until it is slightly over the top of the wooden frame.

Screed the slab with the help of a partner. This smooths out the concrete and exposes any low spots. Drag a 2-by-4 across the top of the frame with a side-to-side motion. Fill in any low spots, and screed the slab again.

Finish the concrete with a bull float. Start with the float on the near edge (close to you). Push the float across the slab, keeping the back edge of the float in the air. When you reach the end of the slab, lay the float flat on the slab and pull it back toward you.

Cover the concrete with a plastic sheet. Add water to the concrete to keep it damp for a week, covering it back up when you are done. Allow the concrete to cure for four to five days after you stop adding water.

Remove the plastic sheet and wooden frame from around the slab.