How to Build a Straight Form for Concrete

Get the ground ready to start building your concrete form. Determine the size of your concrete slab, and outline the area on the ground using a simple spray paint. Use a shovel and other tools to remove the vegetation and a couple inches of top soil from the area.

Spread gravel along the exposed dirt. The gravel will help to secure the concrete slab into place. Make sure you use enough to cover all of the soil's surface.

Use wood to line the outer edge of the area you cleared out. Make sure none of the leftover grass falls within the concrete form. Pound the pieces of wood into the ground until the height of the wood is at the height the final concrete slab should be.

Take a carpenter's level to check that the wood form is level all the way around. Place the level across corners to ensure that one side won't be higher than the other.

Pound wood stakes on the outside and into the ground to secure the concrete form. These stakes need to be deeper into the ground than the other pieces of wood so that you can use the edge of the wood to level the concrete slab.

Put wire mesh inside the concrete form, and position it so that it is about an inch above the gravel surface.

Pour the concrete into the form, and level it. Wait for the concrete to cure before removing the concrete form.