What Does Radon Mitigation Look Like?
Homeowners who learn their radon level exceeds the EPA action level of 4 picocuries per liter often have the same first question: what does radon mitigation look like once it is installed? The honest answer is that a typical system is surprisingly simple to look at, usually a length of white PVC pipe, a quiet inline fan, and a small monitoring gauge. This guide summarizes EPA and Colorado Department of Public Health and Environment guidance current as of 2026. It is educational only and does not diagnose any condition; testing decisions belong with a certified radon professional.
What does a radon mitigation system look like?
The most common radon mitigation system, known as sub-slab depressurization, looks like a single run of PVC pipe roughly three to four inches in diameter. The pipe starts at a point penetrating the basement floor slab or sits in a sump pit, runs up through the home or along an exterior wall, passes through an inline fan that provides continuous suction, and exits above the roofline where the gas disperses. A small manometer, a U-shaped gauge with colored liquid, is mounted on the pipe to show the system is running. Together these few components form a complete active soil-depressurization system, the most widely installed type of radon mitigation in homes with a slab or basement.
From the inside, homeowners typically see the vertical pipe in a basement corner, utility room, or garage. From the outside, they see the pipe running up an exterior wall to the roof, or a discreet vent stack emerging from the roof if the pipe routes through the interior. The fan is usually located in the attic, garage, or on the exterior, never in occupied living space, so the soil gas it carries cannot leak into the home. The overall footprint is modest, and many systems blend into the house surprisingly well. A well-planned installation can route the pipe so that it is barely noticeable from the curb, which matters to homeowners concerned about appearance.
How does the system actually work?
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock, and it seeps into homes through cracks and openings in the foundation. A mitigation system works by intercepting that gas before it enters living space. The fan creates suction beneath the slab, pulling soil gas up through the pipe and venting it safely above the roof, where it disperses harmlessly in the open air. The discharge point is positioned above the roofline and away from windows so the vented gas dilutes into the atmosphere rather than re-entering the home.
This continuous suction reverses the pressure dynamics that normally draw radon indoors. A home tends to operate at slightly negative pressure relative to the soil, especially in winter when warm air rising inside pulls replacement air, and soil gas, up through the foundation. The mitigation fan counteracts that by creating a stronger suction beneath the slab, so the gas follows the path of least resistance into the pipe rather than into the home.
Instead of soil gas pushing up into the basement, the system pulls it out from under the foundation and routes it outside. The fan runs continuously, drawing little electricity, and the manometer provides an at-a-glance confirmation that the suction is active. The underlying mechanics are explained further in the guide on how to fix radon in a home, which walks through the repair process step by step.
What are the main parts of the system?
A complete mitigation system has a handful of recognizable components, each with a clear role.
The vent pipe
The PVC pipe is the visible backbone of the system. It collects soil gas from beneath the slab and carries it up and out above the roof, and its diameter is chosen to move the required volume of air without creating excessive noise. Proper routing and sealing of the pipe are critical to performance, since leaks or poor routing reduce the system’s ability to draw soil gas out.
The fan
The inline fan provides the continuous suction that makes the system work. It is mounted outside occupied space, in an attic, garage, or on an exterior wall, and sized to the home’s needs based on the soil conditions beneath the slab. A home over tight, low-permeability soil needs a stronger fan than one over loose gravel. Fan selection affects both noise and effectiveness, as detailed in the best radon fan buyer’s guide.
The monitoring gauge
The manometer, a simple liquid-filled gauge, shows whether the fan is generating the expected suction. If the liquid levels equalize, it can signal a fan failure or a blockage that needs attention. This small gauge is the homeowner’s primary tool for confirming the system is still doing its job, and learning to read it takes only a moment.
Are there other system types?
Sub-slab depressurization is the most common approach, but the right design depends on the home’s foundation. Houses with a crawl space often use sub-membrane depressurization, where a heavy plastic sheet is laid over the crawl-space floor and the fan pulls soil gas from beneath it. Homes with drain-tile systems or sump pits may tie the suction point into those features. Older homes sometimes need sealing of foundation cracks to help the active system work efficiently.
Some new homes on the Front Range are built with passive radon-ready systems, a vent pipe installed during construction without a fan. If post-construction testing shows levels above 4 pCi/L, a fan is added to activate the system, which is far cheaper than a full retrofit because the piping is already in place. The broader picture of testing, risk, and reduction across Colorado is covered in the Colorado radon testing guide. The various foundation-specific approaches all share the same goal of intercepting soil gas before it enters living space, adapted to how the home sits on the ground.
What does the installation process involve?
Watching how a system goes in helps homeowners understand what they are paying for and what the finished result will look like. A professional installation typically takes most of a single day. The contractor begins by identifying the best suction point, usually a spot in the basement slab or an existing sump pit, then drills through the concrete to reach the soil and gravel beneath.
From that suction point, the contractor runs the vent pipe upward, choosing a route that balances effectiveness with appearance. Some installations route the pipe through the interior of the home, up through a closet or the garage and out through the roof, which keeps the exterior clean. Others run the pipe up an outside wall, which is simpler but more visible. The fan is mounted in the chosen location outside occupied space, wired to a dedicated circuit, and the manometer is attached to confirm suction.
Sealing and finishing
Sealing is an important final step. The contractor seals the suction-point penetration and any major cracks or openings in the foundation, which helps the fan draw soil gas efficiently rather than pulling conditioned air from inside the home. A well-sealed system performs better, uses less energy, and is less likely to draw expensive conditioned air out of the living space. The contractor then tests the system and, after a settling period, arranges a post-installation radon measurement to confirm the level has dropped below the action level of 4 picocuries per liter, which is the clear proof that the installation succeeded.
The visible result of all this work is modest. A homeowner is left with a length of PVC pipe, a fan tucked out of the way, a small monitoring gauge, and a vent stack on the roof or an exterior wall. The contrast between the substantial work involved and the unobtrusive finished appearance surprises many homeowners, who expect something more conspicuous given the system’s importance.
What can homeowners expect after installation?
Once a system is installed, the home should be retested to confirm radon has dropped below the EPA action level of 4 picocuries per liter. A properly designed and installed system commonly brings levels well below that threshold, often to a small fraction of the pre-mitigation reading. The EPA recommends retesting after installation and periodically thereafter, since radon levels can shift over time. Because no level of radon is entirely without risk, many homeowners are reassured to see a post-mitigation reading not just below 4 pCi/L but well under it, which a competent system routinely achieves.
Day to day, a mitigation system is quiet and low-maintenance. The fan runs continuously and uses modest electricity, comparable to a low-wattage appliance. Homeowners should glance at the manometer occasionally to confirm the system is working and have the fan checked if the gauge readings change. Fans have a finite lifespan and may need replacement after many years of continuous operation.
How does mitigation look different across home types?
The appearance of a radon system varies with the foundation, so two homes can have quite different-looking installations. A basement home usually shows a pipe rising from the basement floor, the most common configuration across the Front Range. A slab-on-grade home has the suction point drilled directly through the ground-floor slab, often in a utility area or garage, with the pipe routed up from there to the fan and out above the roof.
Crawl-space homes look different still. Because there is no slab to draw from, the contractor lays a heavy plastic membrane across the crawl-space floor and pulls soil gas from beneath it, a method called sub-membrane depressurization. The visible result is the membrane sealed across the crawl-space floor and a pipe leading up from beneath it to the fan and roofline. Homes with a combination of foundation types, such as a basement next to a slab addition, may use more than one suction point tied into a single fan and discharge.
What stays consistent across all these variations is the basic kit: a pipe, a fan outside occupied space, a monitoring gauge, and a discharge above the roof. The differences lie in where the suction point sits and how the pipe is routed, not in the fundamental approach. A homeowner comparing systems across different houses will recognize the same components arranged to suit each foundation.
How do you know the system is working?
Confirming performance comes down to two things: the manometer and a post-installation test. The manometer provides an at-a-glance daily check. When the liquid in the U-shaped gauge shows the expected pressure difference between its two sides, the fan is generating suction and the system is active. If the two sides equalize, it signals a loss of suction, which can mean a failed fan, a blockage, or a disconnected pipe that needs attention.
The definitive confirmation is a radon measurement after installation. The system should bring the home below the EPA action level of 4 picocuries per liter, and a post-installation test verifies that it did. Because radon levels can shift over time as a home settles, as renovations change airflow, and as the surrounding soil conditions vary, the EPA recommends retesting periodically, every few years and after any major construction, to confirm the system is still holding levels down.
For Colorado homeowners, where elevated radon is widespread across the Front Range, a well-installed system is a durable, largely invisible safeguard that pays off in long-term peace of mind. The modest appearance of the finished system belies its importance, since it continuously protects the household from a documented health hazard with very little ongoing effort from the homeowner.
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 Health — Centers for Disease Control and Prevention
Front Range homeowners who want their radon level checked or a mitigation system evaluated can reach out through our contact page to connect with a vetted local professional.