What are foundation and soil conditions in ZIP code 73071 (Norman)?

Reviewed by Preston · Updated 2026-11-12

In short: About 35% of ZIP code 73071 is mapped in soils rated high shrink-swell and 38% moderate ¹.

What does the soil survey show for 73071?

ZIP code 73071 covers about 23 square miles of land and had 43,379 people in the 2020 Census ²; its center falls in Norman.

Which soils matter most for houses in 73071?

• Renfrow, about 12% of the area ¹: Very deep well drained soils that formed in material weathered from clayey shale of Permian age ³.
• Grainola, about 9% of the area ¹: Moderately deep, well drained soils that formed in material weathered from shale of Permian age ⁴.
• Norge, about 9% of the area ¹: Very deep, well drained, moderately slowly permeable upland soils that formed in loamy alluvium of Pleistocene age ⁵.
• Port, about 9% of the area ¹: Very deep, well drained, moderately permeable flood plain soils that formed in calcareous loamy alluvium of Recent age ⁶.
• Grant, about 6% of the area ¹: Deep, well drained, moderately permeable soils ⁷.
• Kirkland, about 11%, is land the survey does not rate as soil ¹.
• Urban land, about 6%, is ground the survey maps as covered by buildings and pavement rather than classifying its soil ¹.

What does this mean for houses in 73071?

Clay that swells and shrinks. Where high shrink-swell soil sits under a house, wet spells lift the slab edges and drought drops them, and uneven watering does more harm than uniform change. See perimeter wetting heave, edge drop in drought and tree-root drying.

Flood-prone soils. Floodplain soils are layered stream deposits: softer, wetter and more variable than upland soils, and they flood. See soft soil consolidation and Quaternary alluvium and terraces.

Which soils cover 73071?

Looking for a foundation company near ZIP code 73071?

Companies that serve ZIP code 73071 can appear on the company map in the Homeowner Hub. Paid listings there are marked Sponsored; the library and the AI guide don't rank or recommend any of them.

Buying or selling a house in ZIP code 73071? Realtors who serve the area can be on the same map, also marked Sponsored, and for realtors covers the seller disclosure form, inspections and the sale timeline. Seeing cracks at home? Start with for homeowners.

How were these numbers measured?

We overlaid the ZIP code tabulation area (the Census approximation of a ZIP code) from the Census Bureau ² on the USDA soil survey's map units ¹ and added up the area of each soil. Where a map unit is a mix of soils, its area was split by the percentages the survey lists for its major soils, so shares leave out minor inclusions and do not add to 100%. Shrink-swell is rated by the linear extensibility of a soil's most expansive layer, the survey's measure of how much it changes length between wet and dry (6% or more is high). Water table, bedrock and flooding come from the survey's map-unit summaries: the shallowest water table in any month, the shallowest bedrock, and the most common flooding frequency. Bedrock here includes soft, weathered sandstone and shale that a pier can push through, so it is not the depth where piers stop. These are mapped averages, not a test of any one lot; fill, grading and the soil actually under a house can differ, which is why a site visit or soil boring still decides a repair.

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• Shrink-swell and the active zone