Pouring concrete in cold weather requires an insulator to allow the concrete to cool at a slow rate. If the concrete cools too quickly, the water inside the mix freezes before the concrete cures. This affects the structural integrity of the concrete. One insulator used to slow the cooling rate is plastic. Plastic is placed over the top of the concrete to insulate the warm concrete from the cold air. Typically cold-temperature pours require a concrete mix with heated water.

Step 1

Fill the hot water heater, and raise the temperature to between 150 degrees and 180 degrees Fahrenheit. Fill the wheel barrel with concrete mix and add water. For cold weather, use a dry slump. Slump is the water-to-cement ratio. Check the mix manufacturer's recommendations for slump at different temperatures. Agitate the mix-and-water combination with a shovel until the cement is evenly saturated. This also applies to concrete from a plant. Order a hot-water mix with a low slump.

Step 2

Pour the concrete between the forms, level with the top. Settle the concrete by probing it with the handle of a shovel. Tap the sides of the forms with a hammer to settle the concrete around the forms. Rake the patio's fresh concrete level. Trowel the concrete with a darby float. To do so, slide the float back and forth across the surface of the concrete until the aggregates are submerged below the surface and a light water and concrete film -- cream -- covers the top.

Step 3

Finish the concrete with a bull float. Place the float on one side of the patio and drag it across the top to the other side. Move to the next section and repeat the process. Edge the slab. Put the lip of the edger between the form and the concrete, and slide the edger parallel to the form. This creates a rounded gap between the top inch of the concrete and the slab so when the form is stripped, the concrete does not have a sharp, square edge.

Step 4

Hammer a 10 penny nail every 4 feet, 2-inches deep into the top of the form, on two opposing sides of the perimeter. Tie a nylon string to the top of a nail at one of the corners. This nail is the anchor. Run the string across the patio to the adjacent nail on the opposite corner. Pull the string tight and wrap it around the top of the nail twice. Pull the string back across the patio -- diagonally -- to the nail next to the anchor, wrap it around the top twice and run it to the opposing adjacent nail. Wrap it twice and cross the patio again to the third nail. Continue this process until the entire patio is covered with a web of string.

Step 5

Lay the plastic sheeting across the patio on top of the strings. The strings prevent the plastic from touching the concrete and ruining the finish job you completed. Allow 1 foot to hang over the form onto the ground on each end, then cut the sheet from the roll. Place a cinder block on each end to secure the sheeting in place. Parallel to the first sheet, place a second alongside it. Overlap the first sheet by 6 inches. Again, cut the sheet with a foot on each end to spare, and put a cinder block on the extra length. Cover the entire patio using this method. If you choose to do so, you can place space heaters under the plastic to keep the concrete warm as it cures.