Soil Test
Synonyms: Soil Investigation، Geotechnical Investigation، Soil Report، Site Investigation
Last updated: 2026-09-25
Short Definition
A soil test is a geotechnical investigation done before structural design, drilling boreholes on site and testing samples in the field and laboratory to determine soil type, bearing capacity, groundwater and chemical content, so the engineer can recommend the foundation type and depth.
Overview
Legal Basis
The Balady platform of the Ministry of Municipalities and Housing lists a "soil study report" among the requirements of the building permit service, alongside the title deed, survey decision, contracts with a designing office, a supervising office and a contractor, and inherent defects insurance. This rests on the Saudi Building Code Implementation Law (M/43 dated 26/4/1438H), which makes code compliance a condition for building permits (Art. 6); the code includes the Saudi soils and foundations code SBC 303, which sets soil report requirements and the cases in which one is needed. The report must be prepared and signed by accredited engineers under the Engineering Professions Practice Law (M/36 of 1438H).
Practical Example
The owner of a 600 m² residential plot in east Riyadh hires an engineering office for a soil test before design. The office drills 3 boreholes to 8 m for SAR 4,500. The report shows a silty sand layer that can collapse when wetted down to 1.8 m, then a firm layer with an allowable bearing capacity of 150 kPa, and no groundwater. It recommends removing the upper layer, replacing it with compacted fill and using isolated footings tied with ground beams. The recommendation adds about SAR 25,000 to the foundations but avoids possible settlement if water leaks from the garden or pipes.
Common Mistakes
- ✗Believing soil testing is only for large projects, although the report is a Balady building-permit requirement.
- ✗Using a neighbouring plot's report or an old report instead of testing the actual site.
- ✗Choosing the cheapest offer with too few or too shallow boreholes that do not cover the foundations' zone of influence.
- ✗Ignoring the report's recommendations on resistant cement, waterproofing or soil replacement to save cost.
- ✗Not re-testing when the design changes to a heavier building or adds a basement.
International Differences
In Turkey, a soil and foundation investigation report (zemin ve temel etüt raporu) is required for building permits and reviewed within the building inspection system; in the UAE, municipalities require soil reports for new buildings; and in European countries geotechnical investigations follow Eurocode 7. The Saudi approach is consistent with these practices and is distinctive in listing the report explicitly among the electronic permit requirements on Balady and linking it to the inherent defects insurance path.
