Geotechnical Report
CSI Division 31, Earthwork
A report prepared by a geotechnical engineer based on soil borings, laboratory testing, and site investigation, documenting a site's actual soil and groundwater conditions and providing specific recommendations for foundation design, allowable bearing capacity, and any special considerations, such as expansive soil or a high water table, the project needs to account for.
Why it matters
A structural engineer's foundation design depends entirely on the geotechnical report's soil recommendations, designing a foundation before the geotechnical investigation is complete, or on a generic assumption instead of site-specific data, risks a foundation that doesn't actually match the soil conditions it's built on.
On a real project
A structural engineer designs a building's foundation using the specific allowable bearing capacity and groundwater depth documented in the project's geotechnical report, rather than a generic assumption based on the region's typical soil conditions.
Who this matters most to
A Civil Engineer or geotechnical engineer prepares the report based on soil borings and lab testing. A Structural Engineer designs the foundation directly from the report's specific recommendations.
Where this goes wrong
A developer starts foundation design on a fast-tracked project before the geotechnical report is complete, using a generic bearing capacity assumption to keep the schedule moving. The actual geotechnical report, once finished, reveals significantly weaker soil than assumed, forcing a redesign of the foundation after structural work has already begun.