Improper Drainage and Runoff: Water that pools beside a slab washes away fine particles beneath it, allowing sections to drop, creating uneven concrete. Poorly directed downspouts or broken sprinkler lines accelerate erosion, especially on sloped lots.

Loose or Uncompacted Fill Soil: When the sub-grade wasn’t compacted during construction, the ground compresses slowly under the weight of the slab, leading to settlement and cracked concrete. Homes built on excavated hillsides or infill lots see this problem most often.

Moisture Wicking Through the Slab: Capillary action draws groundwater up into concrete, weakening paste bonds and fostering internal voids. Over time, that hidden decay shows up as surface flakes and widening joints.

Insufficient Reinforcement: Slabs poured without adequate rebar or mesh can’t resist the tensile forces created by earthquakes or expansive soil. The result is random, jagged cracking that travels across the entire panel.

Tree Root Pressure: Fast-growing roots from redwoods, eucalyptus, and other local species push upward on pavement, heaving sections out of alignment. Left unchecked, the roots can eventually split the slab and lift it several inches.