How To Install Pavers Over Concrete
According to a host of paver manufacturers, you can install pavers over concrete without mortar. This can be achieved if you lay down a 1 or 2″ to 1" of coarse sand. This process is almost identical to laying down a paver patio over the ground. However, the installation of pavers over concrete should be done cautiously, because settling, drainage, and cracking can cause problems in the long run. If you want to carry out the installation of pavers over concrete, keep the below tips in mind:
Sand in Joints
When you have finished laying down the blocks, make them firm by using polymeric sand to fill up the joints. While the sand joints remain permeable, if properly set they will help excess water flow through the surface instead of puddling.
Your new concrete patio will be about 3" higher than the concrete slab. Make sure you plan for transitions into other areas. Particularly if your patio adjoins your home. Most property codes specify the length that a masonry patio should measure from a home's siding. Although, you may be required to install flashing to stop water from flowing into the building.
Like any other kind of installation, a concrete paver patio must be firmly edged. This is meant to keep the pavers and sand from squishing and settling around. However, your edging should allow water to drain into the soil. If it is watertight, the patio could become a bowl of water whenever it rains.
The most common problem with laying down pavers over concrete is the inability of water to drain/flow through the blocks into the earth. Before starting the process, make sure the concrete is well sloped and does not puddle. Do not forget this drainage slope when adding your pavers to the concrete patio. Make sure the edge through which water drains stays permeable and low. Additionally, you can drill little drainage holes through your concrete every few inches. This will help puddling water seep straight through the ground.
Rather than worrying about edging, some builders make use of adhesive or mortar to hold the perimeter of pavers in place. You will need a clean boundary by the sand bed to achieve this so that the blocks can stick to the concrete directly. Make sure the sand bed and mortar are of the same thickness, as this will ensure that the blocks are level. Note that this technique can form a nonpermeable edge which can cause water to puddle beneath the pavers.
The condition of the concrete is another consideration. If your concrete slab is in terrible shape or broken, it may be better for you to rip it up and start the whole process again.
You can extend your patio's side by digging out the soil around it. Then installing a proper sand bed and gravel. After which tamping and screeding the sand across the old and fresh areas to make everything level. However, bear in mind that all non-concreted spots will settle, and as time passes your patio might become uneven.