Home Radon Inspection: What Homeowners Need to Know
A home radon inspection is a professional service, not a kit. A licensed measurement specialist arrives with a calibrated continuous radon monitor, follows EPA Protocols, and produces a tamper-evident report — distinct from the $20 charcoal canister a homeowner would mail to a lab. In Colorado, where EPA Zone 1 status and CDPHE data put about half of tested homes above 4 pCi/L, a professional radon inspection is the default during real-estate transactions. This guide covers scope, pricing, vetting, and what to expect. The information reflects EPA and CDPHE guidance current as of 2026 — consult a licensed mitigation professional for elevated results and your physician for any health concerns.
Home Radon Inspection: The Service Defined
A home radon inspection is a measurement service. A licensed Colorado radon measurement specialist places a continuous radon monitor (CRM) in the home for at least 48 hours under closed-house conditions, retrieves the device, downloads the hourly log, and generates a written report comparing the measured value to the EPA 4 pCi/L action level. The service uses NRPP- or NRSB-certified equipment and credentialed personnel. It satisfies real-estate-transaction requirements, post-mitigation compliance, and any scenario where chain-of-custody documentation matters.
Scope of the Inspection
Equipment Setup
The specialist arrives with a CRM — common models include Sun Nuclear 1028 and 1029, RadonAway PRO Series, and AlphaGuard PQ2000. The unit is placed in the lowest livable level of the home, 20 inches above the floor, 12 inches from any exterior wall, four inches from objects. Bathrooms, kitchens, laundry rooms, and closets are excluded. The deployment timestamp is logged in the device.
Closed-House Verification
The specialist verifies closed-house conditions are in effect — windows and exterior doors closed except for normal entry and exit, whole-house fans off, HVAC running normally. For a vacant home, the seller’s agent confirms closed-house conditions have been in place for the 12 preceding hours. CRMs log any movement or significant condition change, so tampering is recorded.
Test Duration
The CRM runs for at least 48 hours, sometimes 72 to 96 depending on the buyer’s contingency timeline. Hourly readings are logged internally. Some advanced units also record temperature, humidity, and barometric pressure for context.
Retrieval and Reporting
The specialist returns at the agreed end time, retrieves the unit, downloads the data, and produces a PDF report. Typical report content: certification number, equipment serial and calibration date, deployment and retrieval timestamps, hourly readings (often as a chart), integrated average, action-level comparison, and recommendation. Reports usually arrive by email within 24 to 48 hours.
How an Inspection Differs From a DIY Kit
A DIY charcoal kit produces a single number from a passive medium mailed to a lab. A home radon inspection produces an hourly time-series with tamper evidence, credential documentation, and an immediate result on retrieval. The accuracy of the two methods is broadly similar for a single measurement, but the inspection’s documentation makes it admissible in real-estate contracts and post-mitigation compliance contexts. The in-batch DIY radon testing decision framework details when each is appropriate.
Pricing on the Front Range
A standalone home radon inspection in the Denver metro and Front Range typically runs $150 to $250. Bundled with a general home inspection — the most common arrangement — the radon add-on is $100 to $200. Post-mitigation confirmation testing runs $135 to $250. Multi-unit testing in larger homes can add $50 to $100 per additional measurement location.
Pricing is broadly stable across Denver, Douglas, Arapahoe, Jefferson, Boulder, and El Paso counties. Mountain-county pricing can run 15 to 25 percent higher due to travel time. The pillar guide on radon testing in Colorado covers county-by-county notes.
How to Vet a Measurement Specialist
Verify Certification
NRPP (National Radon Proficiency Program) and NRSB (National Radon Safety Board) are the two recognized certifying bodies. Ask for the specialist’s certification number and verify it on the NRPP or NRSB online lookup. Colorado does not require state-issued radon measurement licensure — the state defers to the national programs.
Verify Equipment Calibration
CRMs must be calibrated at least annually. Ask the specialist for the calibration date of the unit they plan to deploy. A calibration certificate signed within the last 12 months is the standard.
Check Insurance and References
General liability insurance is standard for any home-services contractor. Ask for proof. References from recent Front Range real-estate transactions are easy to verify with a buyers’ agent or two.
Ask About Bundling
Many Front Range home inspectors hold a radon measurement certification and bundle the radon test into the inspection visit. This is convenient, cheaper than two separate visits, and well-documented. The in-batch home radon inspection bundling pattern is the operating norm. See also the in-batch radon testing home service-vs-DIY comparison.
What the Report Tells You
Below 2 pCi/L: the home is in the lower-risk band. The EPA notes no level is risk-free, but the consensus recommendation is no immediate action. Between 2 and 4 pCi/L: consideration range. Some Front Range homeowners mitigate in this range because regional baselines run high. At or above 4 pCi/L: EPA action level. Mitigation strongly recommended.
If the report shows hourly readings that swing wildly — say 1.5 pCi/L for 12 hours, then 8 pCi/L for 12 hours — the specialist should annotate whether closed-house conditions were maintained throughout. A tampered test can produce false-low or false-high spikes. A reputable specialist will flag any data integrity issue.
When a Re-Test Is Recommended
Borderline results — 3.5 to 5.0 pCi/L — often warrant a confirmatory test. Two short-term tests averaging above 4 pCi/L, or one long-term test above 4 pCi/L, is the EPA’s standard for action. A second short-term pro test on a different week, or a 90-day alpha-track, can confirm. The in-batch accurate radon testing guide details confirmation logic.
Post-Mitigation Inspection
After a Colorado mitigator installs a sub-slab depressurization system, a post-installation test within 30 days of system startup confirms the system brought levels below 4 pCi/L. This confirmation should be performed by a licensed measurement specialist independent of the mitigator when possible, to avoid conflict-of-interest concerns. The post-install result becomes part of the home’s permanent record and is often shared with future buyers.
Scheduling Within an Inspection Contingency
Real-estate inspection windows in Colorado typically run 7 to 10 days from contract acceptance. A 48- to 72-hour CRM test plus 24 to 48 hours for the report fits comfortably inside that window. Schedule the radon test for the same day as the general home inspection so the property is already accessible. The measurement specialist returns later in the week to retrieve. The in-batch test for radon in home guide covers transaction sequencing.
Inspection Frequency Recommendations
EPA recommends radon testing every two years in unmitigated homes. For Colorado homeowners on the Front Range, this translates to a $20 DIY kit every two years as the minimum maintenance routine. Households with a mitigation system should have professional inspections done 30 days post-install, again at one year, and every two to three years thereafter. After replacing a failed fan — typical service life 8 to 12 years — a fresh pro inspection within 30 days of the new fan startup verifies the system is back to spec.
For households selling a home, a pre-listing inspection can identify radon issues before they surface in the buyer’s contingency. Knowing the result in advance allows the seller to mitigate proactively and disclose a clean post-mitigation reading rather than scrambling during the contingency window.
Comparing Pro Inspection Quotes
Quote variation across Front Range measurement specialists can be 15 to 30 percent for the same service scope. The dominant factors are travel distance, equipment overhead, and whether the inspection is bundled with a general home inspection. A standalone pro radon inspection at $250 is not necessarily a worse deal than a $175 inspection — calibration recency, certification depth, and report quality matter beyond price.
Get two or three quotes for any single transaction. Verify each specialist’s NRPP or NRSB certification number with the certifying body’s online lookup. Confirm calibration is within 12 months on the specific device that will be deployed.
What Pro Inspectors Look for Beyond pCi/L
A licensed measurement specialist commissioned for a pre-mitigation assessment notes building features that bear on mitigation system design. Foundation type (full basement, walkout, crawlspace, slab-on-grade). Number and location of slab penetrations. Sump pit presence and condition. Existing passive radon stub if the home was built under radon-resistant new construction code. Sealing condition at the slab-wall joint. HVAC layout and any combustion appliances that could induce negative pressure.
This information feeds the mitigator’s quote and helps the homeowner understand whether a single-pipe system will suffice or whether multiple suction points are needed. The in-batch home radon mitigation system guide covers system-design considerations.
Independent Pro Inspection After a Mitigation Install
Best practice is for the post-mitigation verification test to be performed by a measurement specialist independent of the mitigator who did the install. This avoids conflict-of-interest concerns — the mitigator’s own test could be perceived as motivated to read low. Many Colorado mitigators voluntarily coordinate with a third-party specialist for the verification, accepting the small additional cost in exchange for the credibility benefit.
References
- Find a Radon Measurement Professional — U.S. Environmental Protection Agency
- Find a Radon Professional — Colorado Department of Public Health and Environment
- Radon Testing — Centers for Disease Control and Prevention
- Radon Testing for Home Inspectors — International Association of Certified Home Inspectors
Front Range homeowners and buyers looking for a connection to a vetted radon inspection specialist can reach out through our contact page.