Short answer: no law requires it. But radon is worth a few minutes of your attention anyway. Radon is a naturally occurring radioactive gas that seeps up from soil and rock and can collect inside homes. You can't see it or smell it, and the only way to know your level is to test. The Virginia Department of Health notes radon is thought to cause about 21,000 lung cancer deaths a year nationally, roughly 670 of them in Virginia, which is why buyers in Great Falls test as a matter of routine even though the law doesn't ask them to.
The law, for the record, is clear: the Virginia Department of Health states plainly that no state or federal law requires radon testing prior to a sale, and no law requires a seller to mitigate if levels come back high. It's entirely negotiable between the parties. Virginia's disclosure form does ask whether the property sits in an area the EPA designates for higher radon potential, but like everything else on that form, the seller makes no representations, so it tells you almost nothing about the specific home. In Vienna, agents treat the test as standard practice regardless.
Here's how it usually goes. During your inspection period, a certified tester places a monitor in the lowest livable level of the home for about 48 hours. If the average comes back at or above 4.0 picocuries per liter (the EPA's action level), buyers typically ask the seller to install a mitigation system or provide a credit, and in our market sellers usually agree. In Reston, it's common for the inspection addendum to cover both the test and a mitigation commitment. Mitigation itself is a straightforward ventilation system that vents radon from beneath the home, and it reliably brings levels down once installed.
One quality note: Virginia law requires anyone who tests or mitigates radon professionally to be certified by the National Radon Proficiency Program or the National Radon Safety Board. Don't let someone involved in the transaction run the test themselves. Order it through your agent during the inspection window in Leesburg or anywhere else in Northern Virginia, and you'll walk into closing with one fewer unknown.
FAQ
How much does radon testing cost?
Radon testing is inexpensive relative to the home inspection itself, most inspectors in our area offer it as a modest add-on during the same visit. Ask your inspector for their fee when you book, and schedule it within your inspection contingency window.
How long does a radon test take?
For a real estate transaction, a short-term test runs at least 48 hours, often using a continuous radon monitor placed in the lowest livable level of the home. Long-term tests of 90 days or more are more accurate but impractical on a purchase timeline.
What happens if the radon level comes back high?
Nothing is required by law. But in practice, buyers ask the seller to install a mitigation system or provide a credit, and sellers in our market routinely agree. Mitigation is a ventilation system that vents radon from beneath the home and reliably brings levels down.
Should I test even if the home already has a mitigation system?
Yes, test anyway. A mitigation system should be rechecked to confirm it's still working, since fans wear out and systems can be disturbed during renovations. A quick retest during your inspection period gives you confidence the system is doing its job.