<cite index="6-10,6-11">Guthrie's Port and Grady series clay soils have very high shrink-swell potential, absorbing moisture aggressively in spring and releasing it slowly through summer, while sandier upland soils drain faster but provide less stable subgrade support for concrete.</cite> <cite index="13-1,13-11,13-13">The city contains substantial housing stock from 1940–1969 (28.82%), 1970–1999 (Brady Bunch-era homes), and pre-1939 Victorian and Craftsman structures (18.07%), requiring specialized foundation and site preparation techniques.</cite> <cite index="6-4,6-6">Wet springs with concentrated rainfall March–May and frequent spring thunderstorms quickly saturate clay soils underlying most residential lots.</cite>