Radon Mitigation Companies: What to Know
Once a radon test comes back high, the next step is finding a company to fix it, and the quality of that company largely determines whether the system actually works. Radon mitigation is a specialized trade with its own certifications, codes, and proven techniques, so the contractor you choose matters as much as the equipment they install. This guide summarizes EPA and Colorado state guidance current as of 2026 and is educational only; consult a certified radon professional for installation decisions and your physician for health concerns. Below is what radon mitigation companies do, how to vet them, what they charge on the Front Range, and what a quality installation should include.
What do radon mitigation companies do?
Radon mitigation companies design and install systems that lower the radon concentration in a home to below the EPA’s 4.0 pCi/L action level. The most common method, active sub-slab depressurization, uses a pipe and a continuously running fan to draw radon-laden soil gas from beneath the foundation and vent it safely above the roofline before it can enter the living space. A qualified company diagnoses the home, sizes the system, installs it to code, and verifies the result with a post-mitigation test.
Good mitigation is engineering, not guesswork. The contractor evaluates the foundation type, the soil conditions, and the home’s air pressures to choose the right approach, slab, crawl space, or a combination. They seal entry points, route the vent pipe correctly, and confirm the fan creates adequate suction. The explainer on how a radon mitigation system works covers the physics, and the broader Colorado radon testing guide explains why Front Range homes need this more than most.
A key diagnostic step many homeowners do not see is the communication test. Before committing to a design, a skilled installer may drill a small test hole in the slab and measure how readily air moves beneath the foundation, which determines how many suction points the system needs and how powerful a fan to specify. A home built over tight, poorly drained soil may need multiple suction points to depressurize the whole slab, while a home over loose gravel may need only one. This upfront diagnosis is what separates a system engineered for the specific house from a one-size-fits-all installation that may not actually lower the radon level.
How to vet a radon mitigation company
Radon work is too important to hire on price alone. Several checks separate a competent company from a risky one.
Confirm certification
Reputable radon contractors hold certification from a recognized national program, the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB). Certification means the installer passed an exam and follows established standards. In Colorado, radon mitigation professionals are also subject to state requirements, so confirm the company meets both. Ask for the certification number and verify it.
Check for a guarantee
A confident, qualified company guarantees that the system will bring radon below 4.0 pCi/L, and stands behind it with a post-installation test. If the level is not met, the company should adjust the system at no extra charge. A contractor unwilling to guarantee the result is a warning sign.
Verify insurance and references
Confirm liability insurance and ask for references or reviews from recent local jobs. A company that has installed many systems on Front Range foundations understands the region’s expansive soils and basement-heavy housing. The guidance on choosing a local radon company covers how to compare bids.
Get a written scope and warranty
The proposal should specify the system type, fan model and warranty, pipe routing, sealing work, the guaranteed radon level, and the post-mitigation test. Vague quotes invite disputes later.
What radon mitigation costs
Pricing on the Front Range typically falls in a predictable range, though complex homes cost more.
- Standard sub-slab depressurization (single fan): roughly $800–$2,500 installed.
- Complex homes (multiple foundations, large footprint, finished basement routing): often $2,000–$3,500 or more.
- Crawl space systems requiring a vapor barrier and sub-membrane depressurization: typically at the higher end.
- Post-mitigation test: sometimes included, sometimes a small add-on.
Most straightforward Colorado homes land in the $1,000 to $2,000 band. Beware bids far below market, which can signal an undersized fan, improper venting, or no post-test. The detailed radon mitigation cost guide breaks down what drives the price.
Several factors push a quote up or down. A finished basement adds cost because the installer must route the pipe through finished space without tearing up walls, often running it through a closet or utility chase. Multiple foundation types under one home, a slab-on-grade addition attached to a basement, for instance, may require more than one system. Aesthetic preferences matter too: routing the pipe internally and out the roof costs more than running it up an exterior wall but looks cleaner. Getting two or three written bids lets a homeowner see how different companies approach the same house and whether a low bid is cutting a corner that matters.
What a quality installation includes
A properly installed system does several things that a cut-rate job skips. The vent pipe terminates above the roofline and away from windows so the discharged radon disperses safely. The fan is mounted outside the living space, in an attic, garage, or on an exterior wall, never in a basement or crawl space below the living area, so any leak does not re-enter the home. A manometer (U-tube pressure gauge) on the pipe lets the homeowner confirm the fan is running.
The installer seals major radon entry points, sump pits, foundation cracks, and slab penetrations, to improve suction and efficiency. After installation, a follow-up radon test confirms the level dropped below the action level. The explainer on what a radon mitigation system looks like shows the visible components so homeowners know what they paid for. A system that lacks a roofline discharge, a pressure gauge, or a post-test was likely installed below standard.
What to expect on installation day
A standard mitigation installation usually takes a single day, often half a day for a straightforward basement system. The crew arrives, confirms the planned suction-point location, and cores a hole through the slab or accesses the sump. They install the vertical pipe run, mount the fan outside the living space, seal the suction point and major foundation cracks, and route the discharge above the roofline. The manometer goes on last, and the homeowner gets a walkthrough of how to read it.
The disruption is modest: some noise from the coring, a crew moving through the basement and exterior, and a period afterward when the system must run before the confirming test. The post-mitigation test typically happens a few days after installation, once the system has had time to draw the radon level down to a stable reading. A good company schedules and delivers that test as part of the job rather than leaving the homeowner to arrange it. Knowing this sequence helps a homeowner recognize whether a contractor’s plan is complete; an installer who never mentions the post-test is skipping the step that proves the work succeeded.
Maintaining the system after installation
A radon system is largely passive once installed, but it is not entirely set-and-forget. The fan runs continuously and typically lasts 5 to 10 years before needing replacement, a few hundred dollars when the time comes. The manometer should be checked periodically; if the liquid columns are level, the fan has likely failed and needs attention.
The EPA recommends retesting every two years, and after any major renovation, foundation work, or HVAC change that could alter the home’s air pressures. Selling the home is another good moment to retest. The overview of radon mitigation system maintenance covers the routine. A quality company will explain this upkeep at handoff.
Questions to ask before you sign
A short list of questions separates a competent company from a risky one and protects you during the bidding process:
- Are you NRPP- or NRSB-certified, and can I have the number? Verify it independently.
- Do you guarantee the system will bring radon below 4.0 pCi/L, in writing? A confident installer will.
- Is a post-mitigation test included? If not, the job is incomplete.
- Where will the fan be mounted and where does the pipe discharge? The fan must be outside the living space and the discharge above the roofline.
- What is the fan’s warranty, and what does a future replacement cost? Plan for the 5-to-10-year fan lifespan.
- Will you seal the sump and visible foundation cracks? Sealing improves performance.
A company that answers these clearly and puts the answers in the proposal is one you can trust with the work. Evasive answers or reluctance to guarantee the result are reasons to keep looking. The guide on comparing radon companies covers how to weigh competing bids.
Why getting it right matters in Colorado
Choosing a certified, guaranteed installer at the outset, then maintaining the system and retesting on schedule, is how Front Range homeowners keep radon controlled for the long term. The stakes are higher here than in most of the country: the EPA places Denver, Boulder, El Paso, Jefferson, and most surrounding counties in Zone 1, the highest-risk category, and a large share of local homes test above the action level. A poorly installed or unverified system in a high-radon home leaves residents exposed to a known lung-cancer risk while believing they are protected. Spending a little more for a company that diagnoses, guarantees, and verifies its work is what turns a radon problem into a solved one rather than a hidden one.
References
- Consumer’s Guide to Radon Reduction — U.S. Environmental Protection Agency
- Radon Mitigation in Colorado — Colorado Department of Public Health and Environment
- Radon and Your Health — American Lung Association
Front Range homeowners who need a certified radon mitigation company or a second opinion on an existing system can reach a vetted local professional through our contact page.