Radon Testing in Resale Properties Regulations in Montgomery County

October 1, 2016
That is the effective date of the Montgomery County "Radon Law." The bill was first introduced in 2015 and was proposed by Councilmembers Rice, Katz, Elrich, and Hucker.

The Law

(1) Require the seller of a single-family home (attached or detached) to test for radon or permit the buyer to perform a test on the property. Seller must give a copy of test results to buyer prior to settlement.

(2) Establish certain exceptions to testing for radon.

Montgomery County, Maryland

The law in a Nutshell

Here is a list of the most important things for you to know about Radon Law in Montgomery County.

  1. Applicability: The law applies to both New and Re-sale homes within Montgomery County.
  2. Information Disclosure: Sellers and buyers must be informed of the radon test results before or on the settlement date.
  3. Mandatory Testing: A radon test is required for all homes, regardless of the buyer's interest. Buyers cannot waive this testing requirement.
  4. Mitigation Systems: Homes equipped with mitigation systems are not exempt from testing. The law mandates testing even for properties with existing mitigation systems.
  5. Valid Test Period: If a radon test has been conducted in the past, it must not be more than one year old at the time of settlement.
  6. Crawlspaces and Slabs: Houses on crawlspaces or slabs are not exempt from testing as they may still have radon present and might require mitigation.
  7. Mitigation Not Mandatory: The law aims to inform parties and promote awareness regarding radon levels. Remediation is not a requirement.
  8. Testing Responsibility: Either the buyer or seller can order the test, but the primary responsibility lies with the seller if the buyer does not initiate the test.
  9. Contractual Obligations: Unless there is a radon contingency or similar contractual obligation, the buyer cannot cancel the contract based on the test results or demand the seller to remediate.
  10. Buyer's Right: Buyers cannot waive their right to have a radon test performed on the property.
  11. Enforcement: Failure to comply with this law is considered a Class A violation, enforceable by the Office of the Consumer Protection.
  12. Exemptions: Some incorporated municipalities and some properties are exempt:
    • Homes with ownership interests, such as condos and co-ops (This exemption pertains to ownership structure, not property type or association).
    • Homes to be demolished.
    • Homes in the Town of Poolesville, Town of Kensington, and Town of Barnesville. (Note: The city of Rockville is no longer included in the exemption list as of January 1, 2023).
    • Properties involved in foreclosure or sheriff's sale.
    • Transfers by fiduciaries in the course of the administration of a decedent's estate.

Important Information:

  • The law does not exempt properties based on construction style, age, or type of foundation. All residential properties fall under the testing and disclosure requirements.
  • The law mandates properties to be tested no more than one year before the settlement date. This ensures that the radon test results are current and relevant at the time of property transfer.

Radon Testing in Rental Properties

July 1, 2023
That is the effective date of the Montgomery County "Radon Rental Law." The bill was first introduced in 2022 and was proposed by Councilmembers Rice and Katz.

The Law

  1. Require the landlord to test for radon all single family (attached and detached) and ground-contact or basement units in a multifamily dwelling.
  2. Require the landlord to install a mitigation system when radon levels are at or above EPA action level of 4.0pCi/L.
  3. Require the landlord to retest, when mitigation is needed, by hiring a radon measurement professional. Landlord must share results with tenant.
  4. Allow tenants to perform or hire a radon measurement professional to test for radon.
  5. Require the landlord to disclose to EACH tenant in the building within 14 days if elevated radon levels are present.
  6. Tenants have the right to terminate the lease without any penalties if landlord fails to mitigate within 90 days of confirmed results.


Important Information:

  • Professional measurements supersedes DIY tests. 
  • Long term tests (90+ days) supersedes short term tests.
  • Radon test must be done prior to new leases and lease renewals. 
  • The test must be performed less than three years before the date of the lease.
  • Landlords must share a copy of the EPA's pamphlet is available through electronic link or by hard copy if requested by the tenant.
Singing with friends "testing for radon is the right thing to do!"