It is possible to install pavers over concrete, however, there are certain requirements to be met. Most homes have a “screed line” at the bottom of the exterior stucco which allows airflow to the interior of the wall. Covering this screed line is against code and prevents moisture from being able to breath out from the wall. Another issue to be avoided is installing pavers over severely damaged or cracked concrete. A bedding sand layer is installed over the existing concrete before laying the pavers. If the concrete has wide gaps the bedding sand will eventually fall into the cracks and cause unevenness in the pavers.