Radon Mitigation System for Apartments
Radon mitigation in apartments and multi-family residential buildings is fundamentally different from single-family mitigation in one structural way: tenants cannot install a mitigation system. The work involves penetrations through the building slab, modifications to the building’s shell, and discharge piping that exits above the roofline — all of which sit squarely within the landlord’s or property owner’s responsibility. This guide covers the legal framework, the Colorado disclosure law, HUD compliance for federally subsidized housing, and what tenants can and cannot do when they suspect or confirm elevated radon in a rental unit. This summary reflects EPA, HUD, and CDPHE guidance current as of 2026 — consult an attorney or certified professional for specific decisions about a rental property.
Part of our Radon Mitigation Systems guide — start there for the full picture →
Why tenants cannot install mitigation
A sub-slab depressurization system requires cutting through the building’s concrete slab, installing PVC piping that may pass through multiple units’ walls or chases, mounting a fan in attic or exterior space owned by the building, and creating a roof penetration for the discharge stack. Every one of these steps is a modification to property the tenant does not own. Standard residential leases explicitly prohibit structural modifications without landlord consent, and even with consent, the work would be paid for by the tenant for a permanent improvement that stays with the building when the tenant moves out.
The work also requires permitting in many Front Range jurisdictions, which the building owner would need to apply for. NRPP-certified mitigators do not install systems in rental properties without landlord authorization for these reasons. Tenants who attempt DIY mitigation in a rental face lease violations, potential damages claims, and underperforming systems that may not actually solve the radon problem.
Colorado’s radon disclosure law for residential rentals
Colorado passed a residential radon disclosure law in 2009 (CRS 38-12-803 and related provisions). The law requires landlords offering residential property for rent or sale to disclose certain radon-related information to prospective tenants and buyers. The disclosure includes any known radon test results, any installed mitigation systems, and a state-prepared informational document about radon health risks.
The disclosure is required at lease signing or sale-contract execution. The disclosure does not require landlords to test for radon, and it does not require mitigation. It does require landlords to share information they already have. This is an information-disclosure framework, not an action-requirement framework.
Tenants signing a lease in a Colorado residential rental should receive the radon disclosure as part of the lease packet. If the disclosure is missing, the tenant can request it from the landlord. The state’s Division of Real Estate publishes the informational document that landlords are required to distribute.
What tenants can do
Several tenant actions are appropriate when concerned about radon in a rental unit:
Test the unit independently
Tenants can purchase a DIY short-term radon test kit for $15 to $30 and place it in the lowest occupied level of the unit per EPA test placement guidance. The test runs 48 hours to 7 days and produces a measured indoor radon concentration. A continuous monitor rental costs more but produces faster, more detailed results. Tenants do not need landlord permission to place a passive radon test in their own unit, though landlord permission is required for any test that involves wiring or modifications.
Share results with the landlord
Test results above 4 pCi/L should be shared with the landlord in writing. The written communication creates a documented record of the test result and the request. Some landlords respond promptly with mitigation plans; some are slow or reluctant. Documentation matters for any subsequent action.
Request mitigation
Tenants can formally request mitigation in writing. The request is not automatically enforceable in Colorado — landlords are not legally required to mitigate unless required by a separate provision in the lease or by a HUD compliance obligation — but the written request creates a documented record. Some landlords mitigate voluntarily; others may negotiate or refuse.
Negotiate at lease renewal
At lease renewal, tenants have leverage. The landlord wants the unit occupied; the tenant can condition renewal on mitigation installation. This is the most common practical path to mitigation in market-rate rental property.
Move out at lease end
If the landlord refuses to mitigate, the tenant can move out at the natural end of the lease term. Tenants typically cannot break a lease early over radon concerns under Colorado law unless the lease itself includes a habitability clause that covers radon. Each tenant’s specific situation should be reviewed with a tenant-rights attorney if early termination is contemplated.
Tenants reviewing the broader radon testing pillar overview get more context on the testing methodology that applies in both owner-occupied and rental settings.
HUD compliance for federally subsidized housing
Section 8 housing, public housing, HUD-financed multi-family housing, and other federally subsidized programs have additional radon-related obligations. HUD’s policy framework, published through various housing notices and the Healthy Homes program, identifies radon as an indoor air quality concern that subsidized housing operators should address. HUD has not historically required radon testing in all federally subsidized housing, but the agency has moved toward more explicit testing and mitigation expectations in newer multi-family housing.
Tenants in HUD-financed properties can contact their local public housing authority or HUD field office about radon concerns. Mitigation in federally subsidized housing is the property owner’s responsibility, with HUD providing oversight and in some cases funding support for required improvements.
How mitigation works in multi-family buildings
The technical methodology for multi-family mitigation depends on the building configuration. Stacked townhouses and garden-style apartments typically use sub-slab depressurization similar to single-family installations, but the system is designed at the building scale rather than the unit scale. A single SSD system may serve multiple ground-floor units. Upper-floor units in stacked configurations may not need separate mitigation if the lower-floor system reduces soil-gas entry sufficiently.
Mid-rise and high-rise multi-family buildings have lower radon entry potential because the upper floors are physically distant from the soil source. Ground-floor units in these buildings may warrant mitigation; upper-floor units rarely do. Testing in each unit category establishes which units are above the action level.
Costs for multi-family mitigation vary widely. A single SSD system serving a small multi-family building runs $2,000 to $5,000. A more complex configuration with multiple suction points and zone-specific controls can run $10,000 to $30,000 or more. The cost is a building-improvement expense paid by the building owner.
What if elevated radon is confirmed and the landlord refuses mitigation?
Colorado does not currently have a statute that requires mitigation in rental property when radon tests above the EPA action level. The disclosure law requires sharing information; it does not require action. Tenants facing a confirmed elevated reading and a non-responsive landlord have limited statutory leverage in market-rate housing.
The practical paths forward include:
- Documenting the request and the refusal in writing.
- Consulting a tenant-rights attorney about whether the lease includes any habitability provisions that could be invoked.
- Contacting CDPHE for guidance on the state’s current enforcement posture.
- Filing a complaint with HUD if the property is federally subsidized.
- Planning to relocate at lease end if no resolution is reached.
The asymmetry between owner-occupied and rental housing is a recurring issue in radon policy. Owner-occupied homeowners can install mitigation immediately upon receiving elevated results. Renters depend on landlord cooperation. Some jurisdictions have proposed stronger tenant-protection statutes for radon; Colorado has not adopted such statutes as of 2026.
What landlords should consider
From the landlord’s perspective, voluntary radon testing and mitigation has several benefits beyond the strict legal minimum. Mitigation reduces future liability exposure if a tenant later develops a radon-attributable cancer and pursues a claim. Mitigation supports compliance with the Colorado disclosure law by providing positive disclosure content. Mitigation can be a marketing feature in radon-aware markets like the Denver metro area. The cost is modest relative to typical multi-family operating budgets.
Some Front Range property managers have adopted standing policies of testing every unit on tenant turnover and mitigating any unit testing above 4 pCi/L. This policy aligns the property’s risk posture with EPA’s recommended threshold and removes the case-by-case decision-making that creates disclosure friction. The InspectandTest radon hub covers testing methodology that supports this kind of standing policy.
Condominiums and shared-ownership structures
Condominiums occupy an intermediate position between owner-occupied and rental housing. Individual unit owners may be responsible for their own units; the homeowners’ association is typically responsible for the building shell, the slab, and any common-area mechanical systems. Mitigation installation in a condo therefore requires coordination between the unit owner and the HOA, with the HOA generally authorizing any modifications to the slab or shared structural elements. HOA approval processes for mitigation are increasingly streamlined in Colorado, but unit owners should expect a multi-step approval process before installation can proceed.
Testing protocols specific to multi-family
Multi-family radon testing requires more units to be tested than single-family because indoor concentrations vary unit-by-unit. EPA’s Protocols for Radon Measurement in Schools and Large Buildings provides the foundational methodology. The basic rule is that every ground-floor and below-grade unit should be tested, plus a representative sample of upper-floor units in stacked configurations.
For a small multi-family building with eight ground-floor units, all eight should be tested. For a larger building with 40 ground-floor units, a statistically valid sample plus follow-up testing in any unit with elevated initial results is appropriate. Continuous monitors deployed for 48-hour or 7-day periods are typically preferred over passive charcoal kits in multi-family settings because they produce more reliable data and reduce the chance of measurement error.
Insurance and disclosure for rental property owners
Landlord insurance does not typically cover radon-attributable claims in the way that property-damage policies cover covered perils. Some umbrella insurance policies provide limited coverage for environmental liability claims that could include radon. Rental property owners should consult their insurance broker about specific coverage and consider environmental impairment coverage if multi-family exposure is significant.
Selling a rental property in Colorado requires the same disclosure as selling owner-occupied property — known test results and known mitigation systems must be disclosed. Property owners with elevated unmitigated readings carry disclosure obligations that may affect sale price or marketability. Pre-listing mitigation reduces this friction for the same reasons it reduces friction in owner-occupied sales.
Mobile home parks and manufactured housing communities
Tenants in mobile home parks present a more complicated situation. The tenant may own the manufactured home itself but rent the pad it sits on. Radon entry pathways in manufactured homes include the floor system above the pier-and-beam crawlspace, the utility penetrations, and any skirting that does not adequately exclude soil gas. Mitigation in manufactured homes can be performed by enclosing and depressurizing the crawlspace under the skirting, similar to submembrane depressurization in conventional crawlspaces.
Responsibility for mitigation in manufactured housing depends on the lease structure. Owners of the home typically have authority to mitigate their own structure but may need pad-lease approval to modify the area below the skirting. Park operators have varying postures on tenant-initiated improvements. Documented agreements before mitigation begins reduce later disputes.
References
- EPA radon in multifamily housing — U.S. Environmental Protection Agency
- HUD radon guidance for housing — U.S. Department of Housing and Urban Development
- CDPHE radon program guidance — Colorado Department of Public Health and Environment
- American Lung Association radon resource — American Lung Association
Frequently asked questions
Can a tenant install radon mitigation in an apartment?
No. Mitigation requires structural modifications to the building, which is the landlord's responsibility. Tenants can test independently but cannot install systems without landlord authorization.
Does Colorado require landlords to test or mitigate for radon?
No. Colorado's 2009 radon disclosure law requires landlords to share known test results and informational materials with tenants. It does not require testing or mitigation. Some HUD-financed properties have additional federal obligations.
What can a tenant do if a rental unit tests high for radon?
Document the result in writing to the landlord, formally request mitigation, negotiate at lease renewal, and consider relocation at lease end if no resolution is reached. A tenant-rights attorney can advise on lease-specific habitability provisions.
How is mitigation different in multi-family versus single-family buildings?
The methodology is similar but scaled to the building. A single sub-slab depressurization system may serve multiple ground-floor units. Upper-floor units in mid-rise and high-rise buildings rarely need mitigation because they are physically distant from the soil source.
Front Range landlords or tenants navigating radon questions in rental property can reach out through our contact page for guidance on testing and certified mitigation referrals.
Radon mitigation fans & parts
If a sub-slab depressurization system is the fix, the inline fan is the heart of it. Match the fan to your soil and pipe diameter — or have a certified installer size it.
| Product | Why | Buy |
|---|---|---|
 RadonAway RP145 Inline Fan | Common 4-in. SSD workhorse fan. | Amazon — $152.00 |
 Fantech Rn2 Radon Fan | Quiet operation; energy-efficient. | Amazon — $153.89 |
 Radon U-Tube Manometer | Confirms the system is pulling suction. | Amazon — $8.95 |