Introduction
If your old concrete patio, slab, sidewalk, or porch needs a little uplift or you’re ready to update its look, upgrade your deck by installing pavers over concrete. This simple yet clever solution to old concrete patios can quickly be done with few tools and even less experience.
Any DIY enthusiastic or regular home improvement guy can do this project over the weekend.
Why do it with pavers? Concrete already provides a solid base to install pavers. It just needs to be free of cracks and other imperfections. You can even fix it for this project, as it is pretty easy to fix concrete.
The good thing about installing pavers on top of the concrete is that you save nature by not taking the concrete to landfills, which are full of concrete already. As said before, this is also an easy DIY project. It can be done with sand or mortar/thin set; I’ll explain it below.
Laying pavers on a concrete base
There are a few ways to lay pavers on concrete bases. You can do it using sand, like in the ground, or use something that will adhere the pavers to the concrete like mortar/thinset. If you want to overlay pavers over concrete, here is how to do it both ways.
Set up a good base for pavers.
Before we build anything, the base has to be whole and free of imperfections. There is an article here on how to manage that.
After that, we need to be sure the concrete slab is sloped in the right direction. If not, we can still fix it with mortar/thinset.
We can also fix all the places where there is a place for water puddles when it rains. We don’t want the water to stand there, even under the pavers.
An easy way to see this is using a garden hose to water the concrete slab and then mark the places with a colored pen so we know the places.
I’d not fix slopes with sand, as concrete won’t let water through. If it’s an uphill battle for water to exit, it will still go towards a house or other wrong direction despite the sand. So we fix this first if needed.
So we come to the point that water needs drainage. If we install the pavers with sand, the slope away from the house must still be maintained so the water will go out of our patio.
Sand over concrete installation
For sand installation, an edge needs to be built around the patio. When you have it, you can fill the bottom of the deck with installing sand for the pavers. It works almost the same as when installing pavers in the ground.
You need to compact the sand a little and use a level to screed it level.
Then, you place the pavers into neat rows like in this guide. Cut all the pieces that need to be cut and install from one end to the other, row after row.
Remember to leave little space between pavers if they don’t have auto joints. It would help to put a little sand in the joints after you finish the surface so the whole patio will be compact.
Then it’s just a regular install with sand and how you want to build. Cut stones to fit and fill joints with sand. Remember to leave gaps for the sand; there are usually auto joints. Compact the pavers in the end.
Install pavers over concrete with mortar.
Begin by thoroughly cleaning away any debris or loose and crumbling concrete. A pressure cleaning or acid washing may be necessary for heavily molded or smooth finished concrete.
A quarter gallon of muriatic acid mixed with a few gallons of water will quickly resolve any problems the concrete may have bonded with mortar.
The problem with the smooth surface is that it needs to provide a better surface for the thin-set to adhere to. After pouring and finishing with a float, the slab’s surface has a “glue-like substance that has to be ground off if someone wants to put mortar in it.
The acid will do the same thing here.
Now it’s time to wet the slab entirely before applying mortar and keep it wet as you use more thinset. You don’t want there to be water puddles or water on the surface of the slab.
It just needs to be moist enough for the concrete to change color.
This will stop the slab from sucking all the moisture from the thinset and hardening too fast. This way, the thinset will cure for a longer time, and it will be more challenging.
Also, it will help the thin-set adhere to concrete a little better—the same principle as with concrete.
It would help if you began setting pavers on porches, patios, or other concrete slabs that break against a structure or a sidewalk with the longest and straightest edge. Stack several rows of pavers against the wall and look at the pattern. If it is what you want, continue to the next step; otherwise, make adjustments before spreading any mortar.
A layer of thinset spread about one foot in width with a ¼” notched trowel will begin the first row once you’ve laid it out. Setting larger pavers will help cut down on production time.
Many sets of pavers come disguised as multiple pavers. These can be placed in unique patterns and designs, making manipulating pavers easier and requiring less cutting.
Offset, multiple pavers can be turned to create unique patterns. Cutting the starter paver in half on every other row also offsets patterns for a unique design with minimal cuts.
Stack additional pavers at least two rows before the installation to ensure a proper fit and pattern before gluing them down to the old concrete patio. Spreading a layer of mortar no thicker than two feet at a time prevents the mortar from drying too quickly.
Remember to keep the existing concrete slab wet as you apply the thinset.
Once the pavers have all been set in place, allow the set to dry for 24 hours before walking on it. Once dry, you can begin sweeping paver sand in between the cracks. A push broom and bagged sand are all that is needed.
Fill in all the overflowing cracks, moisten slightly, and then sweep in more sand. In the following days, as the sand settles, clean in more sand as needed.
Conclusion
Are you tired of your drab concrete slab and looking for a way to give it a new lease of life? One option to consider is installing pavers over it. But before you do, it’s important to carefully weigh the advantages and disadvantages of using either sand or thin-set.
While both methods can be effective, it’s crucial to ensure that water is properly managed during installation. Be aware that standing water on your concrete can be a cause for concern, especially when it’s not visible to the naked eye.
So, take the time to consider your options and plan accordingly to ensure a successful and long-lasting installation.
