Properly preparing for your backyard concrete patio is the key to a functional and aesthetically pleasing project. You must ensure the dirt is level, that you dig deep enough to accommodate the concrete, and that you eliminate the potential for subsurface water. These steps take time, but completing them will reduce the potential for cracks and give you a beautiful patio to enjoy with family and friends.
Preparing for a Backyard Concrete Patio
In creating a concrete patio, the most important steps are those that happen long before the pouring truck arrives. You must first mark your work area, which means you need to know the exact measurements of your patio. Use strings and stakes or spray paint to mark out your patio, ensuring every line is perfectly straight.
Conduct Proper Excavation
The next step is to excavate the area with a shovel or mini-excavator (the latter can be rented from heavy equipment companies). Excavation is necessary to prepare your soil to hold the concrete and allow for proper drainage. The excavating process needs to be done as precisely as marking the patio in the first place and starts with digging to the proper depth.
To determine the proper depth, you must first establish the height of your concrete slab. The minimum thickness for a patio is four inches, but if you intend the slab to support a structure like a hot tub or gazebo, you’ll need to increase the depth to six to eight inches. Another two inches should then be added to account for a nice thick layer of gravel.
Build a Framework for the Concrete
You’ll need to build a framework out of wood to give the poured concrete its desired shape. Straight-form boards that are the right size for your project work best, and you’ll want to choose those that are 2×6. Boards 2×12 work great for a shed or garage, but a patio demands 2×6. Some boards may need to be spliced together to achieve the exact length you need.
Poured concrete is strong and can bend your form boards until the shape you want is lost. You’ll therefore need to add extra supports before pouring commences. Every two feet down the length of the boards, use 2×4 stakes and kickers for reinforcement. This is important – the poured concrete will take the shape of your framework box. Building this form straight is therefore crucial.
Level the Ground
Many yards have sloped areas or other imperfections that can cause rippling in your backyard concrete patio. You can prevent these flaws by using a line level and string to identify how much your ground slopes. If your site is imperfect, you’ll need to bring in additional soil to make it flat. A low section may likewise need to be built up. Keep in mind the ground needs to be level before you can lay your gravel.
Create a Stable Base
Concrete is porous, so drainage of your patio can be an issue if you don’t properly prepare your soil. Water under the concrete pad can result in stress cracks throughout the cement as the ground flexes. You therefore need to tamp the soil to keep it flat and improve the longevity of your finished project.
Tamping requires that you pass over the soil three or four times with a hand or mechanical tamper. The former is a heavy pole attached to a flat metal base with two handles on the side. A mechanical tamper, on the other hand, can be rented from most hardware stores and requires much less physical effort to compact the soil. Once you’re finished with this task, the soil should barely show footprints after you walk across it.
A Few Side Notes
If your soil is extra dry, it won’t compact well during the tamping step. You can quickly overcome this by lightly spraying the soil with a garden hose. And if you’re unsure whether or not your soil is too dry, simply grab a handful and crush it into a ball.
The soil has enough water content when it retains its shape after you open your hand. If it crumbles, you need more water. Just be sure you avoid making pools of water, because that won’t help your concrete base.
Add Gravel and Reinforcement
With your base layer of soil compacted, it’s time to add two inches of gravel. Again, this helps with drainage to keep your backyard concrete patio looking beautiful for many years to come. You need to take the same steps with gravel as you did with the soil – tamp it down so it’s smooth and flat. This ensures your concrete forms into a silky smooth pattern once it’s poured.
The final step is to reinforce the concrete to minimize future cracking. Some people choose reinforcing steel mesh, while others use 1/2-inch rebar placed on a 12-inch x 16-inch grid. If you go with the latter, the mesh and rebar will need to be placed on the bottom of your framework and then lifted during the concrete pour so they remain two inches from the bottom of the patio.
Last But Not Least
Finally, you’re ready to have a truck come and pour the concrete. Some people try to mix the concrete themselves, but this can be tedious, especially for a large project. You’ll want to reschedule the concrete pour if the day is hot, windy, or rainy, as these conditions can adversely affect the outcome of your patio.
Common Mistakes to Avoid
Concrete is strong in compression but doesn’t hold up well when any force tries to pull it apart. You can address this tension weakness by reinforcing the concrete with metal rods.
The problem is that most reinforcing rods are made of steel that can easily rust if water sneaks into the concrete. Steel expands when it rusts and causes internal pressure that forces the concrete to come apart. The only way to avoid this is by using corrosion-proof reinforcing rods like galvanized, fiberglass, or epoxy-coated rebar.
Troweling At the Inappropriate Time
Using a trowel to smooth concrete provides an attractive finish to any patio. But this step must happen at just the right time. Doing so too early will lead to the formation of excessive surface water. Troweling too late eliminates your chances of creating a smooth surface because the concrete is no longer soft enough to work with.
The right time to trowel is when the surface water has dried and the concrete is still workable. But that precise moment will vary depending on air temperature and how wet the concrete was to begin with.
Using a Weak Framework
Your finished patio is only as good as the framework you used to hold the wet concrete. For this reason, you want to check and then double-check your framework before the concrete is poured. Review its strength, ensure it’s tall enough, and use plenty of wood and braces to reinforce it. We like the saying, “If in doubt, build it stout.” A weak framework will distort the shape of your concrete and even cause some spots to be thinner than others.
Building a concrete patio takes time. Even if the steps listed here seem manageable, your best bet is to have a team of professionals handle the work. We are licensed, bonded, and insured with years of experience creating beautiful and lasting patios. Learn more about our services by contacting Summit Concrete & Construction today.