Retaining Walls in Arizona — Block, Boulder, or Poured Concrete?
When the yard slopes, the wall holding it back becomes the most important hardscape on the property. Here's how the three real options compare.
Segmental block (Belgard, Pavestone, Keystone)
Most common option under 4 ft. $45–$95/sf of wall face installed. Engineered for the load, includes geogrid reinforcement past 3 ft, drainage gravel behind, weep holes at base. Looks designed, not utilitarian.
Boulder walls
$70–$150/sf installed depending on boulder size and source. Natural look, well-suited to desert landscapes. Critical: each boulder must bear on the one below — not floated in mortar. Bad boulder walls topple in monsoons because they were stacked, not engineered.
Poured / CMU concrete
$110–$220/sf installed. Required past 4 ft tall, or when carrying surcharge (pool deck, driveway above). Engineered drawings + permit required. Can be veneered with stone or stucco to read finished. Strongest option; least forgiving of bad drainage behind.
Drainage is the wall's #1 job after holding dirt
Every retaining wall over 18" needs a perforated drain pipe at base, 12" of clean drainage gravel behind, and a daylight outlet. Walls fail from water pressure (hydrostatic load) far more often than from undersized block.
Permit threshold
Most AZ cities require an engineered permit past 4 ft of exposed wall height (some count from footing). Surcharge walls (pool deck above) require engineering regardless of height. When permitting is included in AE's written scope, AE prepares and submits the required permits and provides the stamped drawings.
