Commercial radon mitigation systems are essential for reducing hazardous radon gas concentrations in workplaces, schools, industrial facilities, and other occupied buildings. An effective system, such as the ones designed and implemented by GeoKinetics, protects occupants, supports regulatory compliance, and helps building owners manage long-term environmental risk.
Most commercial radon mitigation solutions work by creating a controlled pressure differential that keeps radon from entering the occupied space. The system draws radon laden soil gas from beneath or around the structure and safely exhausts it above the roofline.
Understanding the main types of commercial radon mitigation systems and which factors drive system selection is critical for designing a durable, code compliant solution for any commercial property.
How Radon Enters Commercial Buildings
Radon is a naturally occurring radioactive gas that forms from the decay of uranium in soil and rock. It is colorless, odorless, and tasteless, so specialized testing is required to detect it.
In commercial buildings, radon typically enters through:
- Cracks in slabs and foundations
- Floor to wall joints
- Construction joints and cold joints
- Utility penetrations and sumps
- Exposed soil in crawl spaces or mechanical rooms
Commercial radon mitigation strategies are designed to interrupt these entry pathways, either by preventing radon from entering or by capturing it before it can accumulate indoors.
The most common method is active sub slab depressurization (ASD), which uses fans and piping to draw soil gas from beneath the building and vent it safely outdoors.
What Makes Commercial Radon Mitigation Different From Residential
While the core principles are similar, commercial radon mitigation systems often differ from residential systems because of:
- Scale and complexity: Large footprints, multiple wings, and varying floor elevations make it harder to create a continuous pressure field.
- Multiple foundation types: It is common to see a mix of slab on grade, basements, crawl spaces, and grade beams in the same structure.
- HVAC interaction: Commercial airflow patterns, high outdoor air rates, and building pressurization strategies can amplify or counteract radon mitigation efforts.
- Occupancy patterns: High occupant density, sensitive populations, and 24/7 use can tighten acceptable risk thresholds.
- Regulatory expectations: Owners often need to meet specific standards, guidance documents, and long term monitoring requirements for lenders, agencies, or corporate ESG programs.
As a result, commercial radon mitigation system design relies heavily on diagnostics, engineering judgment, and careful coordination with mechanical systems.
Key Factors That Influence System Selection
Choosing the right commercial radon mitigation system is not a one size fits all decision. Important factors include:
- Building size and layout: Large footprints, multiple levels, or interconnected structures often require multiple suction zones and staged systems.
- Foundation type: Slab on grade, crawl space, basement, and structural slabs each call for different details and combinations of techniques.
- Soil conditions: Soil permeability, moisture, and fill materials affect how well a pressure field will communicate beneath the slab.
- Existing drainage systems: Drain tile, sumps, and under slab ductwork can be either obstacles or useful components of a mitigation design.
- Radon concentrations: Higher initial levels may require more aggressive suction, more fans, or hybrid systems.
- HVAC configuration: Supply, return, and exhaust locations, as well as outdoor air strategies, must be considered to avoid creating new pressure imbalances.
- Noise and aesthetics: Mechanical noise, visible piping, and roof terminations must be managed around tenants and architectural constraints.
- Regulatory and client requirements: Local, state, and federal guidance, including EPA recommendations and ANSI/AARST standards, drive design targets and long term monitoring plans.
A professional commercial radon assessment brings all these factors together to determine the most appropriate system type or combination of systems.
Overview of Types of Commercial Radon Mitigation Systems
Most commercial systems are based on soil depressurization and enhanced ventilation, adapted for the scale and structure of the building. Common types of commercial radon mitigation systems include:
- Sub slab depressurization (SSD / ASD): Uses suction points through the slab to pull soil gas from beneath the building and exhaust it outdoors.
- Sub membrane depressurization (SMD): Uses a sealed membrane over exposed soil, usually in crawl spaces, with suction applied beneath the membrane.
- Drain tile depressurization: Connects a fan to an existing under slab drain tile system to collect and exhaust radon from around the foundation.
- Block wall depressurization (BWD): Applies suction to hollow block walls so radon in the wall cavities and at the footing is captured before it enters the building.
- Mechanical pressurization and ventilation (HRVs / ERVs and HVAC modifications): Uses controlled outdoor air and pressure management to dilute and prevent radon entry, often as a supplement to soil depressurization.
The following sections provide more detail on each system type.
1. Active Sub Slab Depressurization
Active sub slab depressurization is the workhorse of commercial radon mitigation. It is typically used in buildings with slab on grade or basement foundations.
An ASD system:
- Creates a negative pressure zone beneath the slab relative to indoor air.
- Draws soil gas and radon through suction points and piping.
- Exhausts the gas above the roofline, away from windows and air intakes.
Sub Slab Suction (SSD)
Sub slab suction is the most common form of ASD. Key features include:
- Suction points core drilled through the slab into the underlying aggregate or soil.
- A network of PVC risers and lateral piping that connects to one or more radon fans.
- Fans sized based on diagnostic testing and static pressure requirements.
- Exhaust discharge points routed above the roof edge to promote safe dispersion.
In large commercial buildings, multiple suction points, multiple fans, and zoned systems are often required to achieve consistent pressure field extension across the footprint.
Sub Membrane Depressurization (SMD)
Sub membrane depressurization is used where exposed soil exists, such as crawl spaces or underslab trenches. The approach includes:
- Installing a durable polyethylene membrane over the soil, sealed at walls and penetrations.
- Creating one or more suction points beneath the membrane.
- Using a fan to draw soil gas from beneath the membrane and exhaust it outdoors.
SMD is frequently combined with SSD in buildings that have a mix of slab and crawl space foundations.
2. Drain Tile Depressurization
Many commercial buildings have perforated drain tile or French drains around the foundation to manage groundwater.
When the drain tile system is continuous and in good condition, it can be adapted for radon mitigation by:
- Connecting a radon fan to the drain tile via a sealed penetration or sump.
- Using the drain network as a low resistance pathway to collect soil gas around the building.
- Exhausting the radon above the roofline, similar to an ASD system.
Drain tile depressurization can be very effective, particularly for large footprints, because the tile already provides extensive communication under or around the slab.
3. Block Wall Depressurization (BWD)
In commercial structures with hollow concrete masonry unit (CMU) walls, block cores can act as hidden radon conduits.
Block wall depressurization involves:
- Sealing the tops of block walls, beam pockets, and cracks in the wall system.
- Creating suction points into the hollow wall cavities.
- Applying continuous suction so radon is drawn from the wall and footing areas and exhausted outdoors.
BWD is often used in combination with sub slab depressurization when both under slab and wall entry routes are present.
4. HVAC System Modifications and Ventilation (HRVs / ERVs)
Mechanical ventilation can play a supportive role in commercial radon control, especially where radon levels are only moderately elevated.
Heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs):
- Bring in controlled amounts of outdoor air.
- Exhaust an equal amount of indoor air.
- Transfer heat or energy across a core to maintain comfort and efficiency.
By increasing air exchange and managing building pressure, HRVs and ERVs can:
- Dilute indoor radon concentrations.
- Help maintain a slight positive pressure in occupied areas relative to the sub slab region.
However, these systems are usually used as supplements, not replacements, for soil depressurization when radon levels are significantly above action thresholds.
Any HVAC change must be evaluated carefully to avoid unintended consequences such as increased stack effect or negative pressure zones that could draw in more radon.
5. Sealing and Caulking
Sealing is not a standalone radon mitigation strategy, but it is a critical part of every commercial system.
A comprehensive sealing scope typically includes:
- Filling cracks in slabs and control joints.
- Sealing floor to wall joints and cold joints.
- Sealing pipe penetrations, conduits, and sleeves.
- Sealing sumps, pits, and utility chases.
Effective sealing:
- Reduces radon entry points.
- Improves the efficiency and reliability of depressurization systems.
- Helps prevent short circuiting of the suction field.
System Design, Compliance, and Long Term Monitoring
Successful commercial radon mitigation requires more than installing fans and pipes. It involves a full project lifecycle approach:
- Professional assessment and diagnostics:
- Baseline radon testing, often with long term or continuous monitors.
- Soil communication testing to determine suction point locations and fan sizing.
- Building pressure diagnostics to understand how HVAC and stack effect influence radon entry.
- Engineering based system design:
- Pipe routing and fan placement that balance performance, energy use, access, and aesthetics.
- Coordination with structural, architectural, and mechanical disciplines.
- Consideration of redundancy, serviceability, and future expansion.
- Regulatory alignment:
- Design and documentation consistent with EPA guidance and ANSI/AARST standards for large buildings.
- Integration with environmental due diligence frameworks, such as ASTM standards for environmental site assessments.
- Awareness of local building codes, permitting, and jurisdiction specific requirements, including agencies such as LADBS where applicable.
- Verification and ongoing monitoring:
- Post mitigation radon testing to confirm performance under normal operating conditions.
- Installation of visual or electronic system monitors so building staff can confirm system operation.
- Periodic retesting and inspection as part of ongoing environmental and health and safety programs.
For complex commercial and institutional structures, owners often rely on specialized environmental and geotechnical engineering consultants to deliver systems that are effective, resilient, and compliant for the long term.
Partnering With a Commercial Radon Mitigation Specialist
Because commercial projects involve larger investments, more occupants, and stricter regulatory expectations than typical homes, a professional commercial radon assessment and system design is essential. The right partner will:
- Evaluate building conditions and radon risk with appropriate diagnostics.
- Recommend the most effective types of commercial radon mitigation systems for your facility.
- Design and implement a system that integrates with existing infrastructure and HVAC equipment.
- Establish a monitoring and retesting plan that aligns with your regulatory, lender, and corporate requirements.
If you are evaluating radon risk for an existing commercial building or planning mitigation for a new facility, engaging an experienced commercial radon and geotechnical team early in the process can significantly improve outcomes and reduce long term risk.
