A radon contingency in a real estate purchase contract is one of the most valuable — and most poorly understood — protections a buyer can include. When written correctly, it gives the buyer the right to test for radon during the inspection period, specifies what happens if elevated levels are found, and establishes who pays for mitigation. When written vaguely, it creates ambiguity that can trap buyers who discover elevated radon without a clear remedy. This guide covers exactly what a radon contingency should contain, how to negotiate it, and what happens at each stage of the process.
What a Radon Contingency Is and Why It Matters
A contingency is a contractual condition that must be satisfied for the purchase to proceed. A radon contingency makes the buyer’s obligation to purchase conditional on radon levels being at or below a specified threshold — or on the seller taking specified corrective action if they are not. Without a radon contingency, a buyer who discovers elevated radon during an inspection has no contractual remedy: they cannot compel the seller to mitigate or reduce the price, and backing out of the contract may forfeit their earnest money.
In high-radon states (Iowa, Pennsylvania, Ohio, Minnesota, Colorado, North Dakota, South Dakota, and others), radon contingencies are standard practice and expected by both buyers and sellers. In lower-radon states or markets where radon awareness is lower, buyers may need to affirmatively request the contingency — but the right to include it exists in all states and should be exercised in any transaction involving a home with a ground-contact foundation.
The Five Essential Elements of a Radon Contingency
1. The Action Level Threshold
The contingency must specify the radon concentration threshold that triggers the contingency. Most contracts use EPA’s action level of 4.0 pCi/L. However, buyers are free to specify any threshold — some use 2.7 pCi/L (the WHO reference level), particularly in households with young children or smokers. Whatever threshold is specified, it should be expressed in pCi/L and should be unambiguous.
Example language: “If the radon test results show a radon level at or above 4.0 pCi/L (picocuries per liter), Buyer may exercise the following remedies…”
Some agents suggest averaging multiple test results — if two short-term tests are placed simultaneously, averaging them provides a more stable estimate than either alone. If the contract specifies averaging, both test results should be documented and the average calculation method spelled out.
2. Testing Protocol Requirements
The contingency should specify who conducts the test, what type of test is acceptable, and under what conditions. Poorly specified contingencies leave room for disputes over whether the test was conducted properly.
Recommended specifications:
- Who tests: “Test to be conducted by an NRPP- or NRSB-certified radon measurement professional” — or, in states with licensing requirements, “by a [state]-licensed radon measurement contractor”
- Test type: “Short-term radon test, minimum 48 hours duration, under closed-house conditions per EPA protocol”
- Cost: “Testing cost to be paid by Buyer” (standard) or “by Seller” (negotiable)
- Timeline: “Test to be completed within the inspection period” — or a specified number of days if separate from the general inspection contingency
3. Available Remedies if Elevated
This is the most critical section. The contract must specify what happens if the test exceeds the threshold. Buyers typically have three options to negotiate, and the contingency should list them:
- Seller installs mitigation: Seller agrees to install a radon mitigation system by a specified deadline (at or before closing, or within X days of test results), at Seller’s expense, performed by an NRPP/NRSB-certified mitigator, with post-mitigation testing confirming results below the threshold before closing
- Seller provides credit: Seller provides a price reduction or closing cost credit in a specified amount (typically $1,000–$2,500) and Buyer handles mitigation after closing
- Buyer may terminate: If Seller declines to mitigate or provide a credit, Buyer may terminate the contract and receive return of earnest money
The contract should specify which remedies apply in which order — for example, Buyer first requests Seller mitigation; if Seller declines, Buyer may accept a credit; if no credit is offered, Buyer may terminate. Without this sequencing, disputes arise over whether a seller can simply offer a nominal credit to avoid a termination right.
4. Post-Mitigation Testing Requirement
If the contract provides for Seller-installed mitigation, it must also require post-mitigation testing before closing. Without this requirement, a seller could install a system the day before closing with no confirmation that it is working. Post-mitigation testing should specify:
- Minimum 48-hour test placed at least 24 hours after system activation
- Test conducted by an independent certified professional (not the installing contractor or the seller)
- Results must confirm levels below the contract threshold before closing obligation resumes
- What happens if post-mitigation results still exceed the threshold (typically: Buyer may terminate or Seller must take further remedial action)
5. Certification and Documentation Requirements
The contingency should require that the seller provide complete documentation of any mitigation work performed, including the installing contractor’s license number and certification, the system specifications, the pre-mitigation radon level, and the post-mitigation radon test result. This documentation is valuable for future disclosure obligations when the buyer eventually sells the home.
Sample Radon Contingency Language
The following is representative contingency language — consult a real estate attorney in your state to ensure compliance with local requirements and standard contract forms:
RADON CONTINGENCY: This Agreement is contingent upon a radon test of the Property resulting in a radon level below 4.0 pCi/L. Buyer shall arrange and pay for a short-term radon test of minimum 48 hours duration, conducted by an NRPP- or NRSB-certified radon measurement professional, under closed-house conditions, within the Inspection Period. If test results show radon at or above 4.0 pCi/L, Buyer shall notify Seller in writing within [3] business days of receiving results. Seller shall then have [5] business days to elect one of the following: (a) install a radon mitigation system, at Seller’s expense, by a certified mitigator, with post-mitigation testing confirming results below 4.0 pCi/L before Closing, with Seller providing complete system documentation; or (b) provide Buyer a closing cost credit of $[amount]. If Seller elects neither option within the specified period, Buyer may terminate this Agreement and receive return of all earnest money. Post-mitigation testing shall be conducted by a certified professional independent of the installing contractor, with results provided to Buyer at least [3] days before Closing.
Negotiating the Radon Contingency
Seller Resistance and How to Address It
Sellers occasionally resist radon contingencies, either because they are unfamiliar with radon or because they are concerned about what a test might reveal. Common seller objections and buyer responses:
- “The home has never had radon issues”: Radon levels fluctuate and are affected by the specific testing conditions. Previous owners may never have tested, or may have tested at a different time of year. The only reliable measure is a current test under proper conditions.
- “We don’t want to pay for mitigation”: Frame the credit option — a $1,500 credit is less expensive for the seller than a failed sale. In most markets, a buyer who discovers elevated radon without a contractual remedy will simply terminate and the seller faces the same issue with the next buyer.
- “This will delay closing”: A 48-hour radon test adds minimal time — it can be run simultaneously with the general home inspection. Post-mitigation testing requires 48 hours but can be planned to fit closing timelines if installation is prompt.
Hot Markets: Protecting Yourself Without Losing the Offer
In competitive markets where buyers are waiving inspection contingencies, waiving the radon contingency as well introduces meaningful health risk. Some approaches that maintain some protection:
- Request pre-listing radon test results from the seller — if they have tested recently, you may be able to evaluate risk before making an offer
- Include a radon contingency but shorten the testing and notification windows to demonstrate buyer speed
- Include the radon contingency but specify a higher threshold (6.0 or 8.0 pCi/L rather than 4.0) — reducing the probability of triggering it while maintaining some protection against extreme levels
- If you must waive the contingency, budget for post-closing mitigation if needed and consider it a known potential cost of the home purchase
Frequently Asked Questions
What should a radon contingency include?
A complete radon contingency should specify: (1) the radon threshold that triggers it (typically 4.0 pCi/L); (2) who conducts the test and what protocol applies; (3) the available remedies if elevated — seller installs mitigation, seller provides credit, or buyer may terminate; (4) post-mitigation testing requirements if the seller installs a system; and (5) documentation requirements for any mitigation work performed.
Can I negotiate a lower radon threshold in my purchase contract?
Yes. The threshold in a radon contingency is a negotiated term. Buyers with young children or smokers in the household may specify 2.7 pCi/L (the WHO reference level) rather than EPA’s 4.0 pCi/L. Sellers have the right to reject or counter-propose a higher threshold. The final threshold is whatever the parties agree to in writing.
Who pays for radon testing in a real estate transaction?
By convention in most markets, the buyer pays for the initial radon test as part of their due diligence costs, similar to the general home inspection. If the test reveals elevated levels and the seller agrees to mitigate, the seller bears the mitigation cost. Post-mitigation testing cost is sometimes included in the mitigation quote or split between parties — the contract should specify this.
Can I back out of a home purchase because of radon?
Only if your purchase contract includes a radon contingency that allows termination upon elevated results and the seller declines to remediate. Without a radon contingency, backing out due to radon would constitute breach of contract and could forfeit your earnest money. This is precisely why the radon contingency must be included in the initial offer, not added after the fact.
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