Radon and renovating, finishing a basement or weatherizing

Finishing a basement

• Test the area first. The EPA says it is especially important to test before converting an unfinished basement into living space.⁠¹
• Fix it during the project if you need to. If the test shows a problem, radon-resistant techniques can be included inexpensively as part of the renovation.⁠¹ It is generally less expensive to install a radon reduction system before or during a renovation than afterward.⁠²
• Test again when it’s finished.²

Weatherizing, heat pumps and other system changes

The Health Department says to test again after significant changes to your home’s structure or mechanical systems.⁠⁴ The EPA notes that radon problems show up in well-sealed and drafty homes alike.⁠¹ If your project changes how the house is sealed, heated or ventilated, a test before and after tells you whether your level changed.

If you already have a radon system

• Ask about the warranty. Before major changes such as finishing a basement, the EPA says to ask your radon contractor whether they could void any warranties.⁠⁶
• Adding on? For a new foundation, ask your radon contractor what’s needed to keep radon low throughout the home.⁠⁶
• Retest afterward in the lowest lived-in area, to make sure the work didn’t make the system less effective.⁠⁶ Is my radon system working?

Building new

Radon-resistant features cost less to build in than to add later: the Health Department estimates $250 to $750 during construction.⁠⁷ See Radon-resistant new construction.