How to Pour a Concrete Patio Slab

Measure and mark the edges of the patio with wooden stakes and string. Space stakes 16 inches apart around the outside edge of the proposed patio. Use the string level to level the tops of the stakes. The tops of the form boards will be even with the tops of the stakes. Allow a slight slope of the slab away from the house so water will drain away from the slab.

Scrape off the grass inside the patio area and dig out the area, depending on how deep you want the slab to set and how thick you want the concrete. Rake the area flat.

Nail the form boards to the inside of the wooden stakes to outline the slab area. Cut pieces of reinforcing wire mesh to fill in the shape of the patio slab. Lay a single layer of the cut mesh pieces on the inside of the forms.

Calculate the surface area of the patio -- roughly the length of the slab times the width. Multiply the surface area in square inches times the thickness of the slab in inches. Divide the total by 46,650 to determine how many cubic yards of concrete to order from the concrete supplier. Plan your pour for the morning hours and order the delivery of the concrete for that time. You'll need at least one helper to pour the slab.

Lay the screed board across the forms at one end of the patio area. When the truck arrives, begin pouring the wet concrete into the frame along the front edge of the screed board. Place one helper on either end of the screed board and begin working it back and forth and sliding it forward along the edges of the form to spread the concrete evenly in the form. The screed board ensures the rough surface of the patio is level.

Float the entire surface of the patio with the concrete float by raking it back and forth across the wet concrete till the surface is smoothed and any aggregate is pressed down into the slab, leaving a wet "skin" across the surface. Allow the concrete to set until the surface begins to appear dry.

Flat trowel the surface of the slab by raking the flat trowel back and forth across the surface of the slab. Lift the leading edge of the trowel slightly as you work the surface. Use the plywood sheet to kneel out on the slab as you work. The plywood will keep your knees and hands from sinking into the slab as you trowel the surface. Work it until you work up a wet skin again. Allow the concrete to dry until the surface appears dry.

Test the surface by gently brushing with the garage broom. If it leaves dark streaks or crumbles, the slab is still too wet to finish. Re-trowel the area and wait. When the broom leaves light streaks in the surface without darkening the color of the concrete, it's ready to apply the broom finish. Brush straight back and forth all in one direction -- one pass only to create a slight textured finish that gives you traction when you walk on the slab if it's wet. Allow the slab to cure overnight before walking on it. Give it a week before building or putting weight on it.