Before the structural engineer draws any foundation, they need to know what lies beneath the ground: is the soil firm rock, loose sand, or clay that swells with moisture? At what depth does a suitable bearing layer start? Is there groundwater or salts that attack concrete? This is the job of the soil investigation report, which is one of the requirements for a building permit on the Balady platform. This guide explains what the report is, its technical reference, what it determines, why skipping it is risky, when it is carried out, and how to read its findings.
What Is a Soil Report?
A report prepared by a laboratory or specialist body after drilling boreholes on site and taking and testing samples. It describes the soil layers, their properties and bearing capacity, and makes foundation recommendations.
The Technical Reference
The Saudi soils and foundations code (SBC 303) is the reference for site investigation and foundation design requirements, including site testing, soil classification and problematic soils.
What Does the Report Determine?
- Soil bearing capacity on which foundations are designed.
- Foundation type: isolated, strip, raft or piles.
- Foundation depth.
- The need for replacement and material and compaction specifications. Read: Excavation, soil replacement and levelling.
- Groundwater level and its effect on waterproofing.
- Problematic soils: such as sabkha, expansive and collapsible soils.
- Salts and sulphates affecting the cement type and waterproofing.
Foundation Types and What They Relate To
| Foundation type | Usually suits |
|---|---|
| Isolated footings | Good bearing soil and low-rise buildings |
| Strip footings | Load-bearing walls or closely spaced loads |
| Raft | Low bearing capacity, heavy loads or a basement |
| Piles | A deep bearing layer or tall buildings |
The choice directly affects cost. Read: How structural design affects cost.
Why Skipping It Is Risky
A foundation designed on assumptions can lead to settlement and cracking years later, and foundation repair is among the hardest and most expensive repairs. Conversely, a conservative assumption can lead to oversized foundations and extra cost. Read: Cracks in buildings.
When Is It Carried Out?
Before the final structural design, and after demolition if there is an old building on site. Read: The correct order of permits. If the project has a basement next to existing buildings, the report is the basis for designing the shoring. Read: Excavation shoring.
How to Read the Report
- The number, depth and location of boreholes.
- The description of layers in each borehole.
- The recommended bearing capacity and foundation depth.
- Groundwater level, if any.
- Chemical test results and recommendations for cement and waterproofing.
The structural designer translates these recommendations into a design, and the supervisor checks that construction follows them.
Frequently Asked Questions
Is the soil report mandatory?
It is one of the requirements of the building permit service on Balady.
Can I use a neighbouring plot's report?
It is not advisable; soil can differ between plots, and the report must be for your site.
How many boreholes?
The code and the specialist determine it according to the area, number of floors and site conditions.
Do I need a new report to add a floor?
The structural assessment may need to verify the foundations' capacity. Read: Structural assessment for an additional floor.
What if the soil during excavation differs from the report?
The supervisor informs the structural designer to review the design before continuing.
How Abak Engineering Consultancy Helps
Abak is an accredited engineering office in Riyadh that coordinates soil investigation with accredited bodies, designs foundations on its findings to the Saudi code, and supervises excavation, replacement and foundation works. Learn about our structural design services, or Learn more about our Structural Drawing Review & Approval service. contact us.
Regulatory information is based on the Balady platform and the Ministry of Municipalities and Housing, and procedures may be updated by the competent authority. Last reviewed: October 2026.