What You Need to Know Before You Start
Pouring a cement patio is a project you can do yourself if you have a few weekends, basic tools, and patience with the weather. The work breaks into five main stages: preparing the ground, building the frame, mixing and pouring the concrete, finishing the surface, and letting it cure. Most homeowners can handle the first four stages. The hardest part is usually not the pouring itself but getting the ground level and keeping the concrete from cracking as it dries.
A typical 12-by-16-foot patio (about 192 square feet) takes two to three days of active work spread across a week or more, depending on weather and how much prep your yard needs. You will need to rent or buy a concrete mixer, a wheelbarrow, a shovel, a level, and finishing tools. If your yard slopes badly or has poor drainage, you may want to call a professional—fixing those problems before pouring saves you from a patio that cracks or pools water.
Key Takeaways
- The ground must be compacted, level, and sloped slightly (about one-eighth inch per foot) so water drains away from your house.
- Build a frame from 2-by-4 lumber, stake it firmly, and check that it is level before you pour concrete into it.
- Mix concrete in batches or order ready-mix delivered by truck, depending on the size of your patio and your equipment.
- Finish the surface while the concrete is still wet—smooth it, broom it for traction, or add texture—then cover it and let it cure for at least a week before walking on it.
- Concrete cracks as it dries; control where cracks form by cutting shallow grooves (control joints) into the surface while it is still soft.
Preparing the Ground and Checking Drainage
Start by marking out the patio area with chalk or string. Dig out the top 4 to 6 inches of soil and grass. The depth matters because you need room for the concrete plus a base layer underneath. Remove roots, rocks, and debris as you go.
Once the area is excavated, compact the soil firmly. You can rent a hand tamper or plate compactor from a tool rental shop for about $20 to $40 a day. Compact in layers as you work, not all at once at the end. Loose soil under concrete will settle unevenly, and the patio will crack or develop low spots that hold water.
Check the slope with a long level and a tape measure. The patio should slope away from your house at about one-eighth inch per foot—so a 12-foot-wide patio should be one and a half inches lower at the far edge than at the house. This slope is gentle enough that you will not notice it when you walk, but it keeps water from pooling. If your yard naturally slopes the wrong way, you may need to dig deeper on one side or add fill on the other.
Lay down 2 to 4 inches of gravel or crushed stone as a base. This layer helps water drain and keeps the concrete from sitting on wet soil. Compact the gravel the same way you compacted the soil.
Building and Leveling the Frame
The frame holds the concrete in place while it is wet and sets the height and edges of the finished patio. Use 2-by-4 lumber (actual dimensions are 1.5 inches thick by 3.5 inches wide). If you are building a large patio, you may need to add interior supports called stringers every 4 to 6 feet to keep the frame from bowing outward under the weight of wet concrete.
Stake the frame to the ground with 2-by-2 wooden stakes driven 18 to 24 inches into the ground on the outside of the frame, spaced 3 to 4 feet apart. Use 3-inch deck screws or nails to fasten the frame to the stakes. The frame should not move when you push on it hard.
Use a long level (4 feet or longer) to check that the frame is level side to side and slopes correctly front to back. Adjust the stakes by driving them deeper or pulling them up slightly until the frame sits where you want it. This step takes time but prevents a patio that is uneven or drains poorly. Check the level in multiple directions—not just along the edges but diagonally across the frame as well.
Mixing and Pouring the Concrete
For a patio smaller than 100 square feet, you can mix concrete in batches using a portable mixer or mixing by hand in a wheelbarrow. For anything larger, order ready-mix concrete delivered by truck. Ready-mix is usually cheaper per cubic yard and much faster for large jobs, though you will pay a delivery fee and need to be ready to pour as soon as the truck arrives.
To calculate how much concrete you need, multiply length times width times depth (in feet) and divide by 27 to get cubic yards. A 12-by-16-foot patio that is 4 inches deep needs about 2.4 cubic yards. Add 10 percent extra for waste and uneven ground.
If you are mixing by hand, follow the ratio on the concrete bag—usually about three parts gravel, two parts sand, and one part cement powder, plus water. Mix until the concrete is the consistency of thick oatmeal: wet enough to pour but stiff enough to hold its shape. If it is too dry, it will not flow into corners; if it is too wet, it will be weak.
Pour the concrete into the frame and spread it with a shovel, working it into corners and against the frame edges. Do not just dump it in a pile and expect it to level itself. Use a straight board (called a screed board) laid across the top of the frame to strike off excess concrete and level the surface. Work the screed board back and forth in a sawing motion as you move it across the patio.
Finishing the Surface While Wet
While the concrete is still wet, you have a window of 30 minutes to several hours (depending on temperature and humidity) to finish the surface. A smooth troweled finish looks polished but is slippery when wet. A broom finish—made by dragging a stiff broom across the surface—is rougher and safer for a patio where people walk.
After screeding, use a hand trowel or float to smooth out the high and low spots left by the screed board. Then drag a broom across the surface in one direction to create a uniform texture. Work in sections so the concrete does not dry out under the broom.
While the concrete is still soft, cut control joints into the surface using a jointing tool or the edge of a trowel. These are shallow grooves (about one-quarter inch deep) that run across the patio every 4 to 6 feet. Concrete shrinks as it dries and will crack; control joints direct those cracks into straight lines where you want them instead of random cracks across the surface.
Curing and Protecting the Patio
Concrete does not dry and harden the way paint does. It cures through a chemical reaction that takes time and moisture. For the first week, keep the concrete moist by misting it with a hose or covering it with plastic sheeting. Do not let it dry out completely, and do not let it get rained on heavily during the first 24 hours.
Wait at least three days before walking on the patio and at least a week before parking a car on it or moving heavy furniture onto it. The concrete will feel hard after a few days, but it is still gaining strength. Full strength takes about 28 days, though most of the hardening happens in the first week.
If the weather is very hot and dry, mist the patio twice a day for the first week. If it is cold (below 50 degrees Fahrenheit), curing slows down and may take longer. If rain is forecast within the first 24 hours, cover the patio with plastic sheeting weighted down at the edges.
Common Problems and How to Avoid Them
Cracks that form in random patterns usually mean the ground underneath was not compacted well or the concrete was mixed too wet. Compact the soil thoroughly before you pour, and mix concrete to the right consistency—stiff enough to hold its shape but wet enough to pour.
A patio that slopes the wrong way or has low spots means the frame was not level or the ground was uneven. Spend extra time checking the frame with a level in multiple directions. If you discover the problem after pouring, you cannot fix it without breaking up the concrete and starting over.
Concrete that cracks along straight lines is actually normal—that is what control joints are for. If you did not cut control joints, the concrete will crack anyway, but in random places. Always cut control joints while the concrete is soft.
A surface that is too slippery happens when you trowel it smooth. Use a broom finish instead, or wait until the concrete is fully cured and explore a non-slip coating.
When to Call a Professional
Call a concrete contractor if your yard has serious drainage problems, slopes steeply, or has poor soil that will not compact. If you are not confident using a level or are uncomfortable working with concrete, a professional can handle the whole job in one or two days and may provide the result.
You should also hire a professional if you want decorative finishes like stamped patterns, colored concrete, or exposed aggregate. These require skill and special tools that are not worth buying for a one-time project.
Frequently Asked Questions
How thick should a patio be?
A residential patio should be 4 inches thick. This is thick enough to support foot traffic and light furniture without cracking. If you plan to park a car on it regularly, go to 5 or 6 inches, but this requires more concrete and cost.
Can I pour a patio in cold weather?
Concrete cures slowly in cold weather and can be damaged by freezing before it hardens. Do not pour if the temperature is below 50 degrees Fahrenheit or if freezing temperatures are forecast within 48 hours. Spring and fall are usually the best seasons.
What is the difference between concrete and cement?
Cement is the powder that binds the other ingredients together. Concrete is the finished product—cement plus sand, gravel, and water. When you pour a patio, you are pouring concrete, not cement.
Do I need a permit to pour a patio?
Most cities do not require a permit for a small residential patio, but some do. Check with your local building department before you start. A permit is usually required if the patio is attached to the house or if you are doing major grading or drainage work.
How long before I can seal a patio?
Wait at least 28 days after pouring before explore a sealer. Sealing protects the concrete from water damage and stains, but the concrete must be fully cured first. Some sealers require the surface to be completely dry, which can take several weeks in humid weather.