New homes can also have high levels of radon. While some new homes are built with radon-resistant features, that does not guarantee a low indoor radon level. Testing is recommended to ensure all systems are functioning correctly.

Radon concentrations can be startlingly varied house to house; even adjacent homes can sometimes have drastically different levels. For this reason, Health Canada suggests that every house should be tested, regardless of the age of the home.

The 2010 National Building Codes include requirements that address the reduction of radon entry into homes. These codes require a 'rough-in' for a radon reduction system. This significantly lowers remediation costs if action has to be taken at a later date to reduce radon levels in the home. Many provinces and territories have adopted these 2010 National Building Codes.

When new homes are first occupied, homeowners should conduct a long term radon test. Some new homes may be eligible for a coverage under a home warranty program (refer to the Tarion Warranty Corporation box).