DIY: Forming Concrete Slabs With Troughs

Determine the area for your proposed slab and choose a place that is large enough to pour it. Excavate this site, removing any items and grass from a patch 2 to 3 square feet larger than the planned slab. Construct the form for your slab out of melamine-coated 2 by 4 lumber cut to the correct specifications; attach the boards together with flat-headed screws.

Lay the form into place in the middle of your prepared area, with the center over the place where your slab should end up. Place wooden stakes around the outside of the form, pushing them firmly halfway into the ground so that they are snug against each side of the form. Remove the tops of the stakes with a saw to make them all even with the top of the form.

Dig a trough along the interior of each side of the form, making each trough approximately 4 inches deep and no wider than the widest part of your shovel spade. Moisten the soil in the center of the form with water, being careful not to get any in the troughs. Tamp the dirt within the form to create a level, firm surface.

Pour concrete into the form until it is about 1 inch deep in the center (about 5 inches deep at the edges). Lay 1 reinforcing rod atop the concrete for every 3 feet of pour area. Wrap a single long piece of rebar around the inside of the form, about 2 inches from each side, bending it at the corners.

Secure the rebar to itself where it overlaps and to the reinforcing rods where they cross using tie wires. This will prevent the metal from rubbing, which can cause rusting and corrosion. Fill the rest of the form with concrete.

Tap the outside of the pour form with a hammer to settle the concrete. Screed the surface of the concrete to make it level. Smooth the surface by floating it with a rubber float three times; wait 30 minutes between each float.

Wait 2 to 3 hours for most of the water on the surface of the concrete to evaporate. Drag a straight metal trowel from one end of the form to the other in straight lines to finish the top of the concrete slab. Cure the concrete in the form 3 days, misting the surface with water once each day, then remove the form once the concrete is dry.