2024 Ontario Building Code Updates: Mandatory Radon Mitigation for New Homes

Why the New Ontario Building Code Radon Rules Matter

The 2024 Ontario Building Code (OBC) introduces a major update to improve home safety: mandatory radon mitigation rough-ins in all new residential construction. This proactive measure ensures that homes across Ontario are better prepared to reduce radon exposure—a leading cause of lung cancer.

What Is Radon and Why Should You Care?

Radon gas is a naturally occurring, radioactive gas that seeps into homes from the soil. It is odorless, invisible, and tasteless, making it impossible to detect without specialized testing. Long-term exposure to high radon levels is the second leading cause of lung cancer, after smoking.

Previously, Ontario’s Building Code only required radon mitigation in designated high-risk areas. However, radon levels can be elevated anywhere, so the new 2024 OBC requirements now apply province-wide to all new homes.

Key Changes in the 2024 Ontario Building Code

✅ Mandatory Rough-In for Radon Mitigation Systems

As of January 1, 2025, all new homes in Ontario must include a rough-in for a subfloor depressurization system. This allows homeowners to easily install an active radon mitigation system if high radon levels are detected.

✅ Province-Wide Requirement

Unlike previous codes that applied only to high-risk areas, this update makes radon mitigation standard for all new homes—ensuring better indoor air quality and long-term health protection for residents.

How These Changes Benefit Homeowners and Builders

🏡 For Homeowners:

• Test for radon as soon as you move in. Winter months are ideal for accurate readings.

• Use the pre-installed rough-in to install an active radon mitigation system if levels exceed Health Canada’s guideline of 200 Bq/m³.

• Prevent long-term health risks and create a healthier living environment.

🏗️ For Builders and Developers:

• Ensure compliance with the 2024 OBC radon mitigation requirements for all permit applications submitted on or after January 1, 2025.

• Enhance home value by proactively integrating radon protection into new builds.

• Go beyond the minimum by considering full radon mitigation systems in known high-radon areas.

Why Proactive Radon Mitigation Matters

By making radon mitigation rough-ins mandatory, the 2024 OBC aims to:

✅ Protect Public Health – Reduce lung cancer risks caused by radon exposure.

✅ Improve Indoor Air Quality – Ensure cleaner, safer air in new homes.

✅ Simplify Future Mitigation – Make radon reduction easier and more cost-effective.

What to Do Next: Stay Ahead of Radon Risks

• If you’re a homeowner, schedule a radon test as soon as you move into a newly built home.

• If you’re a builder, ensure compliance with the 2024 Ontario Building Code radon mitigation rules.

• Stay informed and take action to create safer, healthier homes across Ontario.

For more details on the 2024 Ontario Building Code updates, visit the official Ontario government website.

Proactive radon mitigation starts now—protect your home, your health, and your future!