How to Test Your Home for Radon (Step by Step)
Testing your home for radon is one of the easiest things you can do for your family's long-term health. It costs about $15, takes 48 hours, and requires very little effort on your part. The hardest part is remembering to do it.
Here is exactly how to do it right.
Get the right kit for your situation
You have two main options. Pick the one that fits your situation.
The right choice for most first-time testers. You get a result quickly. If it comes back low, you can relax. If it comes back high, you know to act. Short-term kits use a charcoal canister that you leave in your home, then mail to a certified lab. Results come back within a week of the lab receiving it. Kits that include the lab fee run about $15 to $30.
A more accurate picture of your home's actual annual average. Radon fluctuates with weather and seasons, so a 90-day reading reflects reality better than a 48-hour snapshot. The tradeoff is time. If you have already done a short-term test and want to confirm the result, this is the follow-up.
Electronic devices that measure radon continuously and display readings in real time. These do not replace a certified lab test. They are useful for ongoing monitoring after a mitigation system is installed.
See Tipper's picks for the best radon test kits at every price point.
Figure out where to place the kit
This is where most people go wrong. Placement matters a lot.
Place the kit in the lowest livable area of your home where people actually spend time. Good options:
- •A finished basement where anyone watches TV, works out, or sleeps is the ideal spot.
- •A ground floor bedroom or living room if you have no finished basement.
- •A home office on the lowest level.
- •Anywhere people regularly spend time at the lowest level of the house.
Keep it at least 20 inches above the floor. Position it away from windows, exterior doors, and heating vents. Avoid kitchens, bathrooms, and laundry rooms where humidity and airflow interfere with the reading. A bookshelf, dresser, or side table in a bedroom or living area works perfectly.
Walk your lowest livable level and pick your spot before the kit arrives so you are ready to start immediately.
Run the test under closed-house conditions
Short-term tests need closed-house conditions. This is non-negotiable for an accurate result.
Close all windows and exterior doors at least 12 hours before you place the kit and keep them closed for the entire test period. Normal heating and cooling is fine. Running your HVAC system is fine. Turn off fans that exhaust air outside, including kitchen exhaust fans, bathroom fans, and whole-house fans. A ceiling fan recirculating indoor air is fine.
Open the kit and follow the instructions exactly. Record the start date, time, and location on the form included. Place the canister in your chosen spot with the open end facing up. Do not move it during the test. Leave it alone.
Set a reminder on your phone to close all windows the night before you plan to start.
Mail it to the lab promptly
When the test period ends, seal the canister according to the instructions, fill out the chain-of-custody form, and mail it using the prepaid envelope included. Do this promptly. Radon captured in a charcoal canister begins to dissipate over time, so do not let it sit on your counter for a week.
Results typically come back within a few days of the lab receiving your kit.
Read your results
Your lab report will give you a number in pCi/L. Here is what it means:
Well below the EPA action level. Good news.
Retest every two years or after any major renovation affecting your foundation.
Below the action level, but worth a follow-up.
Consider a long-term test for a more accurate seasonal average. Mitigation is optional but reasonable, especially in rooms where people sleep.
At or above the EPA action level. Fix your home.
Run a confirmatory long-term test, then hire a certified mitigation contractor.
Significantly elevated. Take action sooner rather than later.
Skip the long-term confirmation test. Contact a certified contractor and schedule mitigation.
One important note: a short-term test captures a snapshot rather than a seasonal average. If your result is between 4 and 8, confirm with a long-term test before spending on mitigation. If it is above 8, just fix it.
Use RadonLookup's contractor directory to find certified mitigation professionals in your area if your result comes back elevated.
Retest on a schedule
Testing once is not a permanent answer. Radon levels change as soil shifts, foundations settle, and homes are renovated.
- •Retest every two years under normal circumstances.
- •Retest after any renovation that affects your foundation or basement.
- •Retest if you move into a home that has not been recently tested.
- •Retest after a mitigation system is installed to confirm it is working, then annually after that.
A $15 test every two years is a reasonable price for knowing your home is safe. Tipper does it on schedule, same as the smoke detector check on the first of the month.
Put a retest reminder in your calendar right now. Two years goes faster than you think.
A note for home buyers and sellers
Radon at a real estate transaction deserves its own conversation, separate from the step-by-step testing guide above.
If you are buying, request a radon test as part of your inspection. A short-term test during the inspection period gives you a result before you close. If levels are elevated, mitigation can be negotiated as a condition of sale. A mitigation system typically costs $800 to $2,000 and is a reasonable thing to ask a seller to address.
If you are selling, test before you list. Knowing your number ahead of time means no surprises during inspection. If levels are elevated, fixing it before listing is cleaner and cheaper than negotiating a credit mid-sale. Many buyers today know to ask about radon, especially in high-risk states.
See Tipper's full guide to radon and real estate for everything you need to know before a transaction.