Building a concrete patio is something that you can do yourself in about three days. The following guidelines give you an idea of what is required but are not meant to be complete instructions. Please consult an expert.
- Plan your patio. Decide how big you want the patio and mark off the area. For a 50 square foot patio, you need 25 bags of pre-mixed concrete. Make sure you have all of the necessary concrete tools and an automatic concrete mixer. If you do not want to purchase these tools, you can rent them from a home improvement or hardware store.
- Excavate the area for the concrete patio with a garden shovel. Excavate six inches deep so that you can have a two-inch layer of gravel beneath four inches of concrete. This is especially important in the north, where the freezing and thawing cycle can cause drainage problems. The gravel allows for adequate drainage, which prevents cracking due to frozen water trapped beneath the patio.
- Build a form to act as a frame to hold the gravel and concrete. You can build the form from wood or strong plastic or rubber. Sink it into the ground, lining the entire border of the patio area. If you want the patio flush with the ground, make the top of the form level with the surrounding lawn.
- Put in the gravel, tamping it down firmly to avoid later shifting. Install two-inch high flat pieces of rock on top of the gravel to act as supports for rebar reinforcing.
- Install the rebar grid by putting the rebar pieces every two feet front to back and right to left. At places where pieces of rebar intersect, secure them together with wiring. The rebar acts as a concrete unifier and also provides additional support to your patio.
- Mix the concrete in the automatic mixer. Make sure that you follow the directions for adding water.
- Pour the concrete into the area prepared for the concrete patio. Begin at the end of the patio farthest away from the location of your mixer. If needed, you can build a ramp to make it easier to transport the concrete (usually in a wheelbarrow). Have plenty of filler rocks on hand to add to the mixture. Pour as fast as possible, and in order to do this, you must have everything prepared as much as possible beforehand.
- Use bull and darby floats to smooth the surface and embed aggregate beneath it. Stop floating when water starts to bleed onto the surface of the slab.
- Cut initial control joints in the concrete patio using a mason’s trowel. Place the joints every three or four feet and make them two inches deep. As you do this, watch for a watery layer to appear. It will disappear on its own, but wait for it to disappear before proceeding. A jointer will help you finish the control joints. Make a clean groove about one inch deep.
- Finish the surface with any desired design elements.
- Lay plastic over the concrete patio for proper “curing” and to prevent the patio from drying too fast. Leave the plastic on for a week and then do not stress the patio a lot for at least two more weeks.
For further information About concrete and options for a concrete patio.