Installing Pavers on Concrete
“I have a poured concrete patio I would like to cover with pavers, can I do this and how?”
If the conditions are right, yes, but there are a few key tips to keep in mind.
Condition of Existing Concrete: Firstly, your concrete slab needs to be in excellent condition, no significant cracking or deterioration.
Slope: The existing concrete pad must slope away (min 1” of fall for 8 feet of run) from any structures to ensure drainage.
Installation: The most important tip, you must create a drainage layer (1” of bedding sand) below the pavers. In doing so you allow for any water to drain away from pavers and off of the concrete slab (remember, the thinner the bedding layer, the greater risk of damaging the pavers). This drainage layer of coarse sand must also be retained by some form of border around the perimeter so that it doesn’t wash away over time. Once the pavers are installed and carefully compacted, and the joints are all straightened (adjust crooked lines with a screwdriver or small pry bar), fill the paver joints as you would on any other regular paver installation. We recommend checking out EasyPro joint compound sand!
Note: Keep in mind the height the paver will add to the concrete slab once installed. Most pavers are 2-3” (5-8cm) in height, plus your drainage layer. Does this still line up with adjoining building access (patio doors etc) and maintain proper step heights?
Adhering border pavers: Mortaring the pavers to the perimeter of a concrete slab is a fairly common practice, however, here in zone 5 or any other zone where there’s freezing weather, this is not recommended. Any water in between the joints could cause problems and it will just be a matter of time before the pavers, mortar and concrete separate. Instead, use Unilock Concrete Adhesive which is much stronger and easier to apply.
Below is a diagram to help better illustrate installing your pavers on top of a concrete base.
Caution: Pavers over Concrete
A bedding course of 1/8” clear chip stone on a concrete pad will provide the necessary drainage required, but will provide little or no “give” when final compaction of the pavers is attempted. You also run the risk of damaging the pavers.
Therefore we highly recommend that you make the necessary height adjustments (if any) to the individual stone units to achieve a flat surface. You may attempt to compact any slight variances out using a small vibratory plate compactor that is fitted with a protective pad. Cease any further compaction if damage occurs.