How to Read a Geotechnical Report?
Read a geotechnical report in this order: the executive summary and recommendations first, then the boring logs, then the lab results — and treat the recommendations section as instructions, not suggestions. The report tells you what the soil is, what it can support, and exactly how to build on it. Owners, architects, and contractors all read the same report differently; the recommendations section is the part everyone must follow.
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Start with recommendations
This section states the foundation type (spread footings, piers, piles), allowable bearing pressures, estimated settlements, lateral earth pressures for retaining walls, pavement sections, and site preparation requirements. It is written for the design team to implement directly. If the recommendations say 'drilled piers to 25 feet,' that is not a suggestion — it is the engineered basis of the structural design.
Understand the boring logs
Each log shows soil layers by depth with SPT blow counts (higher = denser/stronger), groundwater depth, and lab classifications. Look for the bearing stratum the recommendations reference, note fill versus native soil, and check groundwater — high water tables affect excavation, waterproofing, and liquefaction. The logs represent conditions at discrete points; soil varies between borings.
Limitations and what to do with them
Every report has a limitations section: the findings apply to the explored locations, conditions can differ elsewhere, and the geotechnical engineer should review the final plans and observe construction. Heed it — the most expensive geotechnical failures come from ignoring the recommendation for construction observation, then discovering the bearing stratum is not where the report said it was.
The bottom line
Read recommendations first, boring logs second, limitations always. The report is instructions for the design team — and have the geotechnical engineer review plans and observe the foundation work.
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