Transactions
Radon in a house sale
A property transaction is where most Americans encounter radon for the first time, usually about a week before closing and with no idea whether the number in front of them is a problem. It is also where testing is done under the most pressure and with the most incentive for someone to interfere with it.
The mechanics are well established, and a radon finding almost never kills a deal. It changes the price by roughly the cost of a system.
If you are buying
Test it, and test it properly
Ask for the history
Has the house been tested before? Is there a system already? A seller who has a prior result usually has to tell you, and a system with no paperwork is worth asking about.
Use a professional
In a transaction, use a certified measurement professional rather than a mail-order kit. Continuous monitors log hourly readings and record tampering, which a charcoal canister on a shelf cannot.
Protect the conditions
Closed-house conditions start 12 hours before the test and hold throughout. An open basement window during the test lowers the reading, which is precisely why tamper-resistant monitors exist.
Negotiate on the number
At or above 4 pCi/L, ask for a system installed before closing or a credit to install one after. Get the post-mitigation test either way.
If you are selling
Test before you list, not after you are under contract
A radon result discovered during the inspection period arrives at the moment you have least leverage and least time. The same result found before listing is a line item you handle at your own pace, from your own contractor, at your own price.
If the house needs a system, installing one before listing turns a negotiating point into a feature. A documented system with a post-mitigation test showing the level below 2 pCi/L closes the subject permanently.
If the house tests low, you have a document that pre-empts the question, which is worth having in a Zone 1 county where every reasonable buyer will ask.
New construction
Radon-resistant features cost far less to build in
Building the pipework into a new house during construction costs a small fraction of retrofitting it later, because the aggregate, the membrane and the riser all go in while the slab is still open. A passive system installed this way relies on the stack effect alone, and a fan can be added later if a test shows one is needed.
Many high-radon jurisdictions now require radon-resistant new construction in their building codes. If you are buying new-build in a Zone 1 county, ask whether the house has a passive system and whether the builder will test it after completion.
Cost ranges and construction practice from the EPA Consumer’s Guide to Radon Reduction and EPA guidance on radon-resistant new construction. Disclosure requirements are set by state law and vary; this page is not legal advice. Testing protocol follows the ANSI/AARST standard for real estate transactions.
Questions
Radon and property, answered
Who pays for radon mitigation in a home sale?
It is negotiable and there is no default rule. Common outcomes are the seller installing a system before closing, the seller crediting the buyer an agreed amount at closing, or the parties splitting it. Because a system is typically $800 to $2,500 against the price of a house, it is usually one of the easier points to settle.
Can a seller refuse a radon test?
A seller can refuse any inspection, but refusing a radon test on a house in a high-radon area tends to cost more than the test would. Most contracts make the sale contingent on inspections the buyer chooses, and radon testing is a routine one.
Does a radon system hurt the value of a house?
Generally the opposite. A documented, working system with a post-mitigation test answers the question a buyer's inspector would otherwise raise, and removes an unpriced risk from the deal. What hurts a sale is an untested house in a Zone 1 county, or a high reading discovered late.
Do I have to disclose a radon test result?
Rules vary by state, and many require disclosure of known radon test results and of any installed mitigation system. Several states also require that a specific radon pamphlet be given to buyers. Ask your agent or attorney what your state requires; failing to disclose a result you knew about is the version of this that causes real trouble.
The test came back at 4.1 pCi/L two days before closing. Now what?
This is common and rarely fatal to a deal. The usual path is an agreed credit or an escrow holdback for mitigation, with the work done after closing by a certified contractor. A result that close to the action level is also a good candidate for a confirmatory test, since short-term results move with weather and season.
Next
Start with the county
The EPA zone for the county the property sits in tells you how likely a problem is before anyone spends money finding out.