Pavers and flagstone get the credit or the blame for how a patio looks, but it's the base underneath that decides whether it stays flat. A properly excavated, compacted base — with the right depth for the soil and the load it'll carry — is what stops individual pavers from settling unevenly over time.
Retaining walls follow the same rule from the opposite direction: a compacted base and drainage stone behind the wall are what stop soil from pushing the wall out of plumb. Skip the drainage and water builds up behind the wall until it wins.
Even in a dry climate, an occasional heavy rain finds every low spot a hardscape design didn't account for. Grading the patio itself to shed water — instead of assuming the desert takes care of it — is a small design decision that avoids a much bigger repair later.
Planning a patio, wall or walkway? Call Desert Terrain Landscape at (760) 625-4566 — we'll quote the job in writing.