Short Definition
A foundation is the lowest part of a structure, which safely transfers the building's loads to the soil or rock and is designed not to exceed the soil's bearing capacity or cause harmful or uneven settlement between parts of the building.
Overview
A foundation is the lowest part of a structure, which safely transfers the building's loads to the soil or rock and is designed not to exceed the soil's bearing capacity or cause harmful or uneven settlement between parts of the building. Foundations are divided into shallow foundations — isolated, strip and combined footings and raft (mat) foundations — and deep foundations such as piles, which carry loads down to deeper, stronger strata.
In Saudi Arabia, foundation design is governed by the Saudi soils and foundations code (SBC 303), which sets technical requirements for each foundation type, soil report requirements and the cases in which a report is needed, specifications for excavation, filling and grading, and requirements for waterproofing and dampproofing foundations. A soil study report is a requirement for a building permit on the Balady platform because the choice of foundation type and depth depends on it. Some areas face particular challenges, such as high groundwater, sabkha (salt-flat) soils and salts in coastal zones, and expansive or collapsible soils elsewhere, which call for solutions such as soil replacement, rafts, piles, sulfate-resisting cement and good waterproofing.
Foundation errors are among the most serious and expensive defects to repair, showing up as diagonal cracks, sinking floors and jammed doors. The Building Code Implementation Law therefore makes the supervising designer and the executor jointly liable for collapse and for defects threatening soundness, including hidden ones, and requires inherent defects insurance for non-government buildings; under civil law, the custodian of a building is also liable for damage caused by its collapse unless he proves the cause was not poor maintenance, age or a construction defect.
⚖️ Legal Basis
The Saudi Building Code Implementation Law (M/43 dated 26/4/1438H) mandates the code, including the Saudi soils and foundations code (SBC 303), and makes the designer supervising construction and the executor jointly liable to compensate the owner for total or partial collapse and for defects threatening soundness and safety, including hidden defects (Art. 8(2), added by Royal Decree M/15 dated 19/1/1441H). The Balady platform requires a soil study report and inherent defects insurance to issue a building permit. Art. 131 of the Civil Transactions Law (M/191 dated 29/11/1444H) makes the custodian of a building liable for damage caused by the total or partial collapse of the building unless he proves the damage is not due to poor maintenance, age or a defect in the building.
💡 Practical Example
An owner is building a villa in a coastal district of Dammam. The soil report shows groundwater at 1.5 m depth and a weak sabkha layer down to 2.5 m. The structural engineer recommends replacing the weak layer with fill compacted in layers and casting a reinforced raft with sulfate-resisting cement and full bituminous waterproofing, instead of the isolated footings the contractor had initially priced. Foundation cost rises by about SAR 60,000 (from SAR 90,000 to SAR 150,000), but it spares the owner differential settlement and reinforcement corrosion whose later repair could exceed hundreds of thousands of riyals.
⚠️ Common Mistakes
- ✗Choosing the foundation type by habit or by copying neighbours without a site-specific soil report.
- ✗Neglecting waterproofing of footings and column necks in areas with groundwater or saline soil.
- ✗Backfilling with unsuitable soil or without layer-by-layer compaction, causing tiles and floors to sink later.
- ✗Reducing footing sizes or reinforcement during construction to save cost.
- ✗Adding floors later without checking the capacity of the existing foundations.
🌍 International Differences
Foundation design principles are similar worldwide, but local challenges differ: in the UAE and Qatar, sabkha soils and saline groundwater are widespread, so piles and waterproofing are common; in Turkey, the seismic code imposes strict requirements on foundations and soil improvement; and in Egypt, expansive clays pose challenges in some new cities. Saudi Arabia combines the SBC 303 code, a mandatory soil report for the permit and mandatory inherent defects insurance.
FAQs
Which foundation types are common for Saudi villas?▾
Most common are isolated footings tied with ground beams; rafts are used where soil is weak or groundwater is high, and piles in difficult cases or taller buildings, with the soil report determining the right option.
Is a soil report required for a building permit?▾
Yes. Balady lists a soil study report among the requirements of the building permit service, and the Saudi soils and foundations code SBC 303 sets its requirements.
What are the signs of foundation problems?▾
Diagonal cracks in walls, especially at door and window corners, sinking tiles or floors, doors that no longer close properly, and damp or salt marks at the base of walls.
Who is liable if a building settles because of a foundation error?▾
The supervising designer and the executor are jointly liable to the owner under the Building Code Implementation Law, and the inherent defects insurance policy may respond according to its terms.
Why are foundations waterproofed?▾
To protect concrete and steel from groundwater, salts and sulfates that cause corrosion; the Saudi soils and foundations code includes requirements for waterproofing and dampproofing foundations.
