Building Basements in Riyadh 2026: The Groundwater Battle and Comprehensive Engineering Solutions

Introduction: Basements Between Need and Challenge

With vertical urban expansion and increasing population density in Riyadh the urgent need emerged to utilize underground spaces known as basements to compensate for parking shortages and provide additional storage. However this trend collided with a complex geological and hydrological reality making basement construction in many Riyadh neighborhoods a real engineering battle against groundwater pressure.

Many neighborhoods in the capital suffer from high groundwater levels turning basement construction from simple excavation and concrete pouring into a project requiring careful planning significant additional budget and specialized engineering expertise. In this comprehensive guide we review everything you need to know before deciding to build a basement in Riyadh in 2026.

Geological Reality of Riyadh City

Riyadh is located on the Najd plateau and features diverse geological characteristics that directly affect underground construction decisions. The soil in most Riyadh areas consists of sedimentary layers with varying water permeability creating different challenges from one neighborhood to another.

Groundwater Sources in Riyadh

Riyadh relies on three main water sources which are shallow groundwater deep groundwater and desalinated seawater. Shallow groundwater is the most impactful source on construction projects as it exists at depths close to the surface in some areas. The Wasia formation contains an estimated water reserve of approximately 57 billion cubic meters with salinity levels ranging between 1000 and 3000 milligrams per liter.

Causes of Rising Groundwater Levels

Rising groundwater levels in Riyadh are attributed to several factors related to urban development. Drinking water network leaks represent a major source of the problem in addition to rainwater and excess irrigation water from gardens. In areas without sewage network service septic tank overflows contribute to raising water levels. Additionally closing natural flood channels due to urban expansion has led to water accumulation and formation of buried underground lakes.

Neighborhoods Most Affected by Groundwater Problems

The Royal Commission for Riyadh City and the Municipal Council have identified several neighborhoods suffering from noticeable rises in groundwater levels requiring special attention when considering basement construction.

Northern Riyadh Neighborhoods

Al-Narjis and Al-Arid neighborhoods have experienced repeated complaints about rising surface water levels. Royal Commission studies indicated the necessity of implementing sewage services flood drainage networks and groundwater level reduction networks to control the problem. The north in general is considered water-saturated because it originally contained valleys and flood channels that were closed with urban expansion.

Eastern Riyadh Neighborhoods

Eastern Riyadh faces special geotechnical challenges due to sensitive soil nature. The Royal Commission issued special rules for building foundations on sensitive soil in this area. The Eastern Riyadh Sewage Project has been working for more than 15 years to address these problems.

Other Affected Neighborhoods

Al-Shifa neighborhood and other areas in southern and western Riyadh also suffer from similar problems to varying degrees. Areas near Wadi Hanifa and Wadi Namar require careful study before deciding to build a basement.

Negative Effects of High Groundwater Levels

The Royal Commission for Riyadh City documented a set of negative effects resulting from rising groundwater levels on buildings and infrastructure.

Building Damage

Damage includes cracks and fractures in public and private buildings and corrosion of structural elements such as concrete and reinforcing steel. Floor subsidence occurs inside some buildings and water flooding inside basements making them unusable. Continuous moisture leads to paint damage mold growth and unhealthy environments.

Infrastructure Damage

High groundwater causes asphalt layer cracking and pavement deterioration in public streets. It also leads to corrosion of public utility networks causing significant economic losses alongside health and environmental damage.

Environmental and Health Damage

Swamps and surface water flow create suitable environments for growth and spread of harmful disease-carrying insects. Weed growth in vacant lands negatively affects the city's appearance and residents health.

Basement Construction Costs in Riyadh 2026

Basement construction costs vary significantly depending on land location groundwater level and type of required waterproofing system.

Costs in Normal Areas

In areas not suffering from groundwater problems basement construction costs range between 1200 and 1500 SAR per square meter including excavation concrete and basic waterproofing. For a 100 square meter basement the estimated cost is between 120000 and 150000 SAR.

Costs in Groundwater Areas

In areas with high groundwater costs increase by 30 to 40 percent. Construction requires advanced waterproofing systems salt-resistant concrete and dewatering systems during excavation. Costs may reach 1800 to 2200 SAR per square meter. For a 100 square meter basement costs may reach 180000 to 220000 SAR.

Additional Cost Details

Advanced soil testing costs between 3000 and 8000 SAR depending on number of boreholes and required depth. Dewatering system during excavation costs between 15000 and 40000 SAR depending on project size and duration. Advanced external waterproofing adds between 150 and 300 SAR per square meter. Perimeter drainage system costs between 10000 and 25000 SAR.

Basement Waterproofing Systems

Waterproofing is the first and most important line of defense against groundwater seepage into the basement. Understanding different waterproofing types and choosing the appropriate one according to site conditions is essential.

Positive Side Waterproofing

Applied from the side facing the water source meaning from the outside before backfilling. This type is most effective because it prevents water entry rather than dealing with it after entry. It is applied to external basement walls and under the floor slab before concrete pouring.

Negative Side Waterproofing

Applied from inside after leakage occurs and used in cases where reaching external walls is difficult. This type is less effective than positive waterproofing but sometimes the only option for existing buildings.

Common Waterproofing Materials

Bitumen is one of the most common materials available in roll form or liquid material spread on surfaces. It forms a tight layer preventing water seepage and is resistant to bacteria and fungi. Polyurethane is a liquid material sprayed directly on surfaces forming a flexible fully water-resistant membrane. It features ability to cover fine gaps and cracks. HDPE plastic membranes provide excellent protection and are used in major projects or basements near strong groundwater sources.

Dewatering System

In areas with high groundwater dewatering becomes an essential necessity during excavation and construction phase. Without this system working in a water-filled pit is impossible.

How the System Works

Small wells are drilled around the construction site and submersible pumps installed to extract groundwater and temporarily lower its level below excavation level. Extracted water is directed away from the site through pipes. Operation continues around the clock throughout construction until waterproofing and backfilling are complete.

System Cost and Duration

Cost depends on excavation size water quantity and project duration. Average cost is between 15000 and 40000 SAR for small residential projects. Electricity costs for continuously running pumps must be calculated.

Importance of Specialized Supervision

Dewatering requires specialized engineering supervision to ensure no impact on neighboring buildings or soil stability. Unplanned water extraction may cause subsidence in surrounding lands.

Soil Testing Before Construction

Soil testing is not a luxury but a legal and technical necessity before any construction project especially when planning to build a basement. Testing provides vital information determining project feasibility and actual cost.

What Soil Testing Reveals

Testing determines groundwater level and its seasonal fluctuation soil type and bearing capacity. It reveals presence of salts and sulfates affecting concrete and determines appropriate foundation depth and required foundation type. It also provides recommendations for protecting concrete from chemical factors in soil.

Number of Required Boreholes

For residential villas usually two to three boreholes are drilled at depths proportional to number of floors and basement presence. When planning basement construction borehole depth should exceed planned basement depth by at least two meters.

Soil Testing Cost

Soil testing costs for residential projects range between 3000 and 8000 SAR depending on number and depth of boreholes and required tests. This relatively small cost may save you hundreds of thousands in future problems.

Royal Commission Projects for Lowering Water Levels

The Royal Commission for Riyadh City has been working for years to address rising groundwater levels through multiple projects.

Completed Projects

The Commission completed groundwater level reduction projects in more than 40 neighborhoods in Riyadh. These projects resulted in water levels returning to safe degrees in treated neighborhoods.

Ongoing Projects

The Commission is currently implementing new projects in 13 neighborhoods with lengths reaching 76 kilometers. It will also begin implementing additional projects in three neighborhoods with lengths reaching 27 kilometers.

Continuous Monitoring System

The Commission conducts ongoing monitoring of groundwater levels in various city neighborhoods to detect any changes and determine water quality and quantity.

Basement Design Solutions

Smart design can reduce basement problems and improve usage quality even in difficult areas.

Sunken Courtyard

A sunken courtyard design provides natural lighting and ventilation for the basement reducing feelings of enclosure and helping control humidity. This solution transforms the basement from a dark damp space to a true extension of the home.

Semi-Buried Basement

The optimal design in groundwater areas is the semi-buried basement placed at only 1.5 meter depth. Two-thirds of the structure protrudes above ground while the base and part of the walls disappear into the soil. This design reduces flood risks provides large space with easy access.

Ventilation and Air Conditioning System

An effective ventilation system must be designed for the basement to control humidity and prevent mold formation. Central air conditioning with air drying system helps maintain a healthy environment.

Tips for Buyers When Purchasing a Villa with Basement

Before Purchase

Request the original soil testing report for the project and ensure waterproofing warranty certificates exist. Ask about building history and whether previous leakage problems occurred. Visit the basement during rainy season to ensure no moisture.

Warning Signs

Watch for moisture stains on walls or ceiling and mold or moisture odors. Cracks in walls or floor may indicate structural problems. Paint peeling or bubbling indicates continuous moisture. A continuously running drainage pump indicates groundwater problem.

Specialized Inspection

Hire a specialized engineer to inspect the basement before purchase. Simple inspection cost may prevent you from buying a property with costly problems.

Tips for Builders When Constructing a New Basement

Planning Phase

Start with comprehensive soil testing that determines groundwater level. Consult a specialized geotechnical engineer before deciding to build a basement. Calculate actual cost including waterproofing and dewatering and do not rely on general estimates.

Execution Phase

Ensure external waterproofing is implemented before backfilling and continuously monitor execution quality. Do not rush backfilling before ensuring waterproofing is completely dry. Document all work phases with photos and reports.

After Completion

Test the basement in the first rainy season and monitor any moisture signs. Keep all warranty certificates and contact the contractor immediately when noticing any problem.

Common Mistakes in Basement Construction

Planning Phase Mistakes

Building without soil testing or relying on old testing. Ignoring area history and neighbors problems with groundwater. Reducing waterproofing budget to save costs.

Execution Phase Mistakes

Using internal waterproofing only without external waterproofing. Not protecting waterproofing layer before backfilling leading to damage. Rushing concrete pouring before ensuring site is dry. Not installing perimeter drainage system.

Post-Construction Mistakes

Neglecting maintenance of drainage pumps if present. Blocking ventilation openings which increases humidity. Ignoring early leakage signs until problem worsens.

When Basement is Not a Suitable Option

In some cases deciding not to build a basement is the correct economic and technical decision.

Cases Where Avoiding Basement is Preferred

When groundwater level is very high making cost economically unjustifiable. In small lands where designing comfortable car ramp is difficult without affecting space. When soil is sensitive and unstable. If budget is limited and does not allow proper waterproofing implementation.

Available Alternatives

Shaded outdoor parking or open ground garages. Better use of ground spaces instead of digging down. Sharing in joint parking with neighbors.

Frequently Asked Questions

How much does building a 100 square meter basement in Riyadh cost?

In normal areas cost ranges between 120000 and 150000 SAR. In groundwater areas it may reach 180000 to 220000 SAR including advanced waterproofing and dewatering system.

How do I know if my land has groundwater problems?

The only reliable method is soil testing. You can also ask neighbors about their experiences and check for groundwater reduction projects in the neighborhood.

Can basement leakage be repaired after construction?

Yes but it is very costly. Internal waterproofing and chemical injection are available options but less effective than original external waterproofing. Cost may exceed 50000 SAR depending on problem size.

What is the waterproofing warranty duration?

Warranty duration usually ranges between 5 and 15 years depending on material type and execution quality. Ensure obtaining written warranty certificate from contractor.

Does basement increase property value?

Yes if built correctly and free from moisture problems. A damaged basement may significantly reduce property value.

Is soil testing mandatory in Riyadh?

Yes soil testing is mandatory according to Saudi Building Code for all residential and commercial projects.

What is the best time of year to build a basement?

Best is summer when groundwater level is at its lowest. Avoid building during rainy season.

Can basement be used as residence?

According to building regulations basement use is allowed for recreational purposes and parking provided natural lighting and water drainage considerations are met. It is not allowed for permanent residence.

Conclusion

Building a basement in Riyadh is a decision requiring careful study considering the geological reality of the site actual construction cost and potential risks. Soil testing is the first mandatory step before any decision. In areas with high groundwater an additional cost of 30 to 40 percent must be calculated for advanced waterproofing and dewatering system.

Royal Commission projects for lowering groundwater levels have improved conditions in many neighborhoods but caution remains necessary. Positive external waterproofing is the optimal solution and cannot be compromised regardless of cost. Always remember that correct construction cost from the beginning is much less than the cost of fixing problems later. Consult specialists and do not skimp on quality and appropriate engineering supervision for your project.