Installing a Radon Mitigation System: A Guide
Installing a radon mitigation system is the process of building a sealed pathway — usually a pipe and a fan — that draws radon out from beneath a home’s foundation and vents it safely above the roofline. For Colorado Front Range homeowners, where elevated radon levels are widespread, a properly installed system is the most reliable way to bring an unsafe home below the EPA action level of 4.0 picocuries per liter (pCi/L). This guide walks through what the work entails, how long it takes, and what to expect from start to finish. It summarizes EPA and Colorado state guidance current as of 2026; consult a certified radon contractor for decisions specific to your home.
What Installing a Radon Mitigation System Involves
The most common residential approach is active sub-slab depressurization (ASD). The idea is simple: create lower air pressure beneath the concrete slab than inside the home, so radon-laden soil gas is captured and vented outdoors rather than seeping up into living space. To do that, an installer cuts a suction point through the slab, runs a sealed PVC pipe from that point up and out of the house, and adds an inline fan that keeps air moving continuously.
When the fan runs, it pulls air and radon from the gravel or soil under the foundation, sending it up the pipe and out above the roof, where it disperses harmlessly. The result is that radon never reaches concentrations of concern indoors. Understanding the underlying physics helps, and the radon testing guide for Front Range homeowners explains why this method works so reliably.
Step by Step: The Installation Process
A typical professional installation is completed in a single day. The sequence usually runs as follows.
1. Diagnostic and Suction Point
The installer first assesses the foundation type — slab, crawl space, or a mix — and identifies the best suction point, often in the basement or an attached garage. A hole roughly four to six inches across is cut through the slab, and some material beneath is removed to create a small pit that lets air move freely under the foundation.
2. Routing the Vent Pipe
A three- or four-inch PVC pipe is fitted into the suction point and sealed airtight to the slab. The pipe is then routed upward and out of the conditioned space. Two common paths exist: an interior route through a closet, attic, and out the roof, or an exterior route up the outside wall to above the eaves. Interior routes look tidier; exterior routes are sometimes simpler in finished homes.
3. Installing the Fan and Manometer
The inline radon fan is installed in the pipe run, always in an unconditioned space such as the attic or outdoors — never in the living area, so that any leak in the pressurized section vents outside. A U-tube manometer is mounted on the pipe to give a visible readout of system suction. The fan is wired to a dedicated circuit and runs continuously.
4. Sealing and Finishing
The installer seals visible foundation cracks, the sump pit if present, and other openings that would let conditioned air be drawn in and reduce system performance. The exhaust is positioned above the roofline and away from windows. Many installers add a labeled tag noting the installation date and baseline readings. The guide on the steps to install a radon mitigation system details each phase further.
How Much Does Installation Cost?
For most homes, professional installation of an active sub-slab system runs between $800 and $2,500, with the typical range landing around $1,200 to $1,800. Several factors push the price up or down: the foundation type and complexity, the length and routing of the pipe, the number of suction points needed, and whether the home has a basement, crawl space, or both. Homes requiring multiple suction points or extensive sealing cost more.
Ongoing costs are modest. The fan consumes a small amount of electricity continuously, typically adding a few dollars a month to the power bill, and the fan eventually needs replacement every 5 to 10 years. The guide on radon mitigation system costs breaks down both the install and operating figures in more detail.
Should You DIY or Hire a Professional?
Some homeowners consider installing the system themselves, and DIY kits exist. The work is physically achievable, but doing it correctly is harder than it appears. Sizing the fan for the home’s foundation, locating the suction point for maximum coverage, sealing the slab properly, and routing the exhaust to code all require knowledge that affects whether the system actually lowers radon. A poorly designed system can run constantly while still leaving radon above the action level.
For most homeowners, a certified radon mitigation contractor is the safer choice. Many states, including Colorado, expect mitigation work to follow established standards, and certified professionals carry the diagnostic tools to verify performance. Those who do want to understand the DIY route can review the guide on DIY radon mitigation, which lays out both the possibilities and the pitfalls.
Testing Before and After Installation
Installation should bracket two radon tests. A test before the work confirms the level is elevated and establishes a baseline. A follow-up test 24 hours or more after the system has been running — typically waiting a day for the system to stabilize — confirms it has brought the level below 4.0 pCi/L. Without that post-installation test, there is no proof the system is doing its job.
After the initial confirmation, the EPA recommends retesting at least every two years, and after any fan replacement or significant change to the home. A working manometer shows the fan is moving air, but only a radon test confirms the actual concentration. This testing discipline is what turns a freshly installed system into verified, lasting protection.
What to Expect Long Term
Once installed and confirmed, an active radon system is largely hands-off. The fan hums quietly, the manometer shows steady suction, and the household breathes air kept below the action level. Periodic glances at the manometer, an occasional listen for the fan, and biennial retesting are the only ongoing demands. A documented system with retest results also reassures future buyers, so the installation protects both health and home value for years after the single day of work it took to put in place.
Foundation Type Changes the Approach
Not every home gets the same installation, because the foundation dictates the method. A poured-concrete basement or slab-on-grade home is the most straightforward case for sub-slab depressurization, since the fan can draw soil gas from the permeable layer beneath the slab. A crawl space calls for a different technique — sub-membrane depressurization — in which a heavy plastic membrane is sealed over the exposed soil and the fan draws radon from beneath that barrier.
Homes with mixed foundations, common where a basement adjoins a crawl space or an addition sits on a separate slab, may require more than one suction point or a combination of methods to cover the whole footprint. Older homes with fieldstone or rubble foundations are the most challenging and sometimes need creative routing. An experienced installer assesses these conditions during the diagnostic step, which is why a walkthrough and sometimes a sub-slab communication test precede the actual installation in complex homes.
Passive Versus Active Systems
Some newer homes are built with a passive radon system — a vent pipe routed from beneath the slab up through the roof, relying on natural stack effect rather than a fan to move air. Passive systems are cheaper to install during construction and sometimes reduce radon enough on their own. Often, though, they do not, and they are designed to be easily upgraded to active by adding an inline fan.
Converting a passive system to active is far simpler and cheaper than a fresh installation, since the pipe run already exists. The installer adds a fan in the attic or exterior portion of the existing pipe, installs a manometer, and confirms the result with a test. Homeowners who buy a house with a passive system and a high radon reading should know that activation is usually a modest job rather than a full installation. The guide on radon vent systems explains the difference between passive and active configurations in more detail.
Choosing and Working With an Installer
Selecting the right contractor shapes whether the installation succeeds. Look for certification through a recognized radon proficiency program, ask for proof of insurance, and request references from recent local jobs. A good installer measures the home, explains the proposed suction-point location and pipe routing, and commits to a post-installation test to verify results. Get a written estimate that specifies the number of suction points, the routing, the fan model, and whether the post-test is included.
Be wary of quotes that seem far below the norm, since corners cut on suction-point placement or sealing can leave radon above the action level even with a running fan. Equally, the most expensive bid is not automatically the best. The right choice is a certified installer who diagnoses the specific home, explains the plan clearly, and stands behind a verified result. That combination of competence and accountability is what turns a one-day installation into lasting, confirmed protection for the household.
Why Installation Matters on the Front Range
Colorado sits in the EPA’s highest radon potential zone, and the Front Range geology generates radon abundantly from uranium-bearing soil and rock. The region’s prevalence of basements and the strong winter stack effect, which draws soil gas upward in tightly sealed, heated homes, compound the problem. For many Front Range households, elevated radon is the expectation rather than the exception, which makes a properly installed mitigation system one of the more impactful home-safety investments available.
That regional reality also affects timing. Because radon runs highest in winter, a test that confirms an elevated level and the installation that follows are often most urgent in the colder months. Homeowners who discover a high reading should not delay; the gas accumulates continuously, and the EPA’s identification of radon as the second leading cause of lung cancer after smoking underscores why prompt installation matters. A single day of work converts a home with hazardous indoor air into one kept reliably below the action level.
What Happens If the First Test Fails
Occasionally a freshly installed system does not bring radon below 4.0 pCi/L on the first post-installation test. This is not a failure of the approach but a sign the home needs more. The usual remedies are straightforward: the installer may add a second suction point to extend depressurization across more of the slab, upsize the fan to increase suction, or seal additional foundation openings that are letting the fan draw indoor air instead of soil gas.
A reputable installer treats the post-test as part of the job and stands behind achieving an acceptable result, which is one more reason to choose a certified contractor over a DIY attempt or a bargain operator. After any adjustment, another test confirms the fix. This iterative verify-and-adjust process is exactly why the post-installation test is non-negotiable: it turns the installation from a hopeful assumption into a confirmed outcome. Once the system passes, the household has documented proof that the air is safe, and the system settles into the quiet, low-maintenance operation it will provide for years.
References
- Consumer’s Guide to Radon Reduction — U.S. Environmental Protection Agency
- Colorado Radon Program and Mitigation Standards — Colorado Department of Public Health and Environment
- Radon and Lung Health — American Lung Association
Front Range homeowners ready to install or evaluate a radon system can get in touch through our contact page to connect with a certified local mitigation professional.
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 — $151.37 |
 Radon U-Tube Manometer | Confirms the system is pulling suction. | Amazon — $8.95 |