Illinois Radon Resistant Construction Act: Metro East Guide

What is the Illinois Radon Resistant Construction Act?

While many homebuyers ask about the Illinois Radon Resistant Construction Act, the state formally regulates radon services through the Radon Industry Licensing Act and 32 Illinois Administrative Code 422. For new residential buildings in Metro East areas like Madison and St. Clair counties, the U.S. EPA recommends incorporating passive radon-resistant construction features. The core purpose of these features is to establish a preventative barrier against radon, a naturally occurring radioactive gas and the second leading cause of lung cancer in the United States. By including these features during initial construction, homes become more resilient to soil gas entry, supporting comprehensive radon mitigation efforts.

Key Aspects of Radon-Resistant Construction

• New Residential Construction: Recommended for new homes to prevent soil gas entry.
• Passive System Features: Includes built-in elements to naturally vent soil gas.
• Future-Proofing: Simplifies the process of upgrading to an active system if elevated radon levels are detected.

What does “radon-resistant construction” mean in Illinois?

In Illinois, radon-resistant construction refers to the installation of passive features during new residential builds to reduce radon entry. These passive systems align with U.S. EPA guidelines and simplify future upgrades to an active mitigation system if elevated radon levels are detected in Madison and St. Clair counties.

Gas-Permeable Layer

This foundational element, detailed in EPA guidelines for radon-resistant homes, is a layer of clean gravel, typically four inches thick, placed beneath the concrete slab or flooring system. Its purpose is to allow soil gases, including radon, to move freely underneath the house, preventing pressure buildup that could force radon indoors.

Plastic Sheeting

Positioned directly over the gas-permeable layer and beneath the concrete slab, this durable plastic sheeting acts as a barrier. Its sealed seams further prevent soil gases from entering the living space, providing an additional layer of protection against radon intrusion.

Sealing and Caulking

All below-grade openings in the foundation, such as cracks in floors, construction joints, and utility penetrations, are meticulously sealed and caulked. This critical step minimizes potential entry points for radon gas, enhancing the overall effectiveness of the radon-resistant design.

Vent Pipe

A three-inch or four-inch PVC pipe runs from the gas-permeable layer beneath the foundation, extending vertically through the house, and safely vents above the roofline. This pipe creates a natural pathway for radon to escape to the outside air, relying on natural pressure differentials without a fan.

Junction Boxes

An electrical junction box is installed in the attic, pre-wired to facilitate the easy installation of a vent fan. If post-occupancy testing reveals radon levels at or above the EPA action level of 4.0 pCi/L, this junction box simplifies activating the passive system into a full active mitigation system by adding a fan and an alarm.

Do new Illinois homes with passive radon systems still need testing?

Yes, new homes in Illinois with passive radon systems still require post-occupancy testing. The U.S. Environmental Protection Agency (EPA) strongly recommends this crucial step for all new construction, including properties in Madison and St. Clair counties. While passive systems facilitate future radon reduction, they do not guarantee indoor radon levels will be below the EPA action level of 4.0 pCi/L. The EPA Home Buyer’s and Seller’s Guide to Radon explicitly states that every new home should be tested after occupancy, even if built with radon-resistant features, to ensure effective radon gas reduction.

Why Passive Systems Require Testing

• No Guarantees: Passive features do not automatically lower levels below 4.0 pCi/L.
• Site-Specific Variables: Soil composition and foundation settling affect radon entry.
• Verification: Testing is the only way to confirm the passive system is functioning adequately.

How do passive radon systems become active mitigation systems?

Passive radon systems become active mitigation systems by adding a specialized vent fan to the existing pipework. This straightforward process transforms a basic setup into a continuously operating system that actively reduces radon. If your post-occupancy test shows radon at or above the EPA action level of 4.0 pCi/L, activating the system is the recommended next step to reduce risk in your home. For licensed service, contact Air Sense Environmental today.

Step 1: Post-Occupancy Testing Confirms Elevated Levels

Even with radon-resistant features, the EPA recommends testing every new home after occupancy to confirm radon levels are below 4.0 pCi/L. If test results indicate levels at or above this action level, the passive system is insufficient and requires activation to effectively lower concentrations, as outlined in the Home Buyer’s and Seller’s Guide to Radon.

Step 2: Hire a Licensed Radon Mitigation Contractor

Activating a passive system requires technical knowledge and specialized skills. The Illinois Emergency Management Agency (IEMA) licenses and regulates individuals who provide radon mitigation services, as detailed on the Illinois Department of Public Health radon page. A qualified, licensed contractor will assess your home and design the most effective upgrade plan.

Step 3: Install the Vent Fan and Warning Device

Installing a vent fan into the existing passive pipe is the primary activation step. This fan creates a vacuum beneath your home foundation, drawing radon gas up and safely venting it outside above the roofline. A warning device, typically a manometer, is also installed to visibly indicate that the system is operating correctly, per the Consumer’s Guide to Radon Reduction.

Are new homes safer from radon than older homes in the Metro East?

Evaluating radon risk between new and older homes in the Metro East requires understanding how construction methods impact soil gas entry. The primary difference is that new homes often include built-in passive pipes, whereas older homes typically lack any pre-installed radon infrastructure. New construction simplifies future mitigation because the foundational gas-permeable layer and vent pipe are already integrated into the structure. Older homes require a mitigation contractor to retrofit a complete active system from scratch, which often involves drilling through the existing concrete slab. Despite these structural differences, both types of homes draw radon from the soil and require testing to verify if levels exceed the EPA action level of 4.0 pCi/L.

Comparing Mitigation Approaches

• New Construction: Often includes passive pipes and sealed foundations, making future active mitigation easier.
• Older Homes: Typically lack built-in passive systems, requiring a full active system installation from scratch.
• Equal Risk: Both types of homes draw radon from the soil and require testing to verify safety.

What is the average radon level in Illinois?

While specific statewide averages for Illinois are not provided, the U.S. EPA estimates the average indoor radon concentration for American homes is about 1.3 pCi/L. However, radon levels can vary significantly from home to home, even in the same neighborhood. The EPA recommends taking action if your home radon level is at or above the action level of 4.0 pCi/L, as any exposure carries some risk. Testing is the only way to know your home specific levels.

EPA Action Level Guidelines

• 4.0 pCi/L or higher: Fix the home immediately.
• Between 2.0 and 4.0 pCi/L: Consider fixing the home, as no level of radon is completely safe.
• Below 2.0 pCi/L: Retest in the future to ensure levels remain low.

How often should I retest my new home for radon?

The EPA recommends retesting your new home for radon at least every two years to ensure radon levels remain low, even with radon-resistant construction. You should also retest if you make major structural changes, such as converting an unfinished basement into living space, as renovations can impact radon entry. Post-mitigation testing is also crucial to confirm the system effectiveness. Regular retesting helps maintain safe indoor air quality.

Recommended Testing Intervals

• Every Two Years: As a standard maintenance check for all homes.
• After Structural Changes: Following renovations, additions, or finishing a basement.
• Post-Mitigation: Within 30 days of installing or upgrading to an active system to confirm effectiveness.

Who is legally allowed to install an active radon system in Illinois?

In Illinois, only individuals licensed by the Illinois Emergency Management Agency (IEMA) are legally allowed to install active radon mitigation systems. The Radon Industry Licensing Act requires that all professionals providing radon testing and mitigation services to the public hold current licenses from IEMA. Hiring a licensed contractor helps ensure the system is installed correctly and adheres to state regulations, effectively reducing radon levels in your home.

Benefits of Hiring Licensed Professionals

• Regulatory Compliance: Installations meet strict state codes and standards.
• Proper System Design: The system is tailored to your home specific foundation and layout.
• Post-Installation Verification: The system includes a warning device to confirm proper operation.