How to Build a Poured Concrete Foundation

Measure the dimensions for the foundation with a tape measure and mark the borders with landscape paint, adding 4 inches to the sides for the temporary forms.

Excavate the foundation site by digging down 6 inches, plus the thickness of the concrete. If the foundation will support a structure or driveway, the concrete should be about 6 inches thick. For a patio, walkway or other light use, you only need to pour 4 inches of concrete.

Compact the floor of the expanse until the soil resists your force. The compactor machine will push out air pockets and stabilize the soil for the concrete.

Set 2-by-4 inch form boards in the sides against the interior edges of the expanse. Stack the form boards to equal the thickness of a 6 inch base, plus the thickness of the concrete. For instance, if you're pouring 4 inches of concrete, your form boards need to be at least 10 inches tall. Stack two 2-by-6 inch boards to achieve this minimum height. Screw the forms together at the ends and reinforce them with 1-by-3 inch stakes every 4 feet around the outside.

Add 6 inches of aggregate over the floor and compact it. The sharper edges will fit together when compacted, improving drainage while providing a supportive base.

Lay wire mesh over the aggregate to reinforce the foundation.

Pour wet concrete over the wire mesh, working across from one side to the other. Spread it into corners and over the expanse evenly using a hoe.

Smooth the surface with a floater or trowel, scraping off excess from the sides. If you can't reach the center, drag a long board or straight-edge over the surface to smooth it.

Cover the foundation for about a week so it can dry slowly. Lay wet burlap over the foundation and continuously wet it throughout the week.