The Big Idea: Pull Radon Out Before It Gets In
We know from daily field experience that discovering high radon levels is stressful. Before committing to radon mitigation in Iowa City or anywhere else in the country, many clients ask us: how does a radon mitigation system work? Our first priority is clarifying that this equipment does not simply filter bad air out of your house.
The machinery actually stops the radioactive gas before it enters the living space, effectively bringing indoor readings below the EPA action level of 4.0 pCi/L.
We achieve this by flipping your home’s natural pressure dynamic using active soil depressurization. Radon gas constantly rises from the dirt, and your house acts like a chimney during the winter heating season to pull that soil gas inside. Our installed system creates a slight vacuum under your concrete slab instead, forcing the gas into a PVC pipe so it vents safely above the roofline.
The Parts of a Radon Mitigation System
A standard setup involves several specific radon mitigation system parts, including a suction pit, PVC piping, an inline fan, and a discharge point. We assemble these core pieces to create a continuous pathway for soil gas to escape safely.
1. The suction pit
The process starts by coring a clean hole through your basement floor, usually 4 to 6 inches across. We then dig out a small pit in the gravel or dirt underneath. A typical installation requires removing 5 to 10 gallons of material to create this void. Our hollow cavity gives the fan a much larger surface area to pull air from, which helps the vacuum spread efficiently under the entire slab.
2. Sealed PVC pipe
Standard Schedule 40 PVC pipe connects directly to the suction pit and runs to the outside of the home. We use this specific durable plastic because US building standards require it to prevent cracking over time. Every single joint gets glued, and the spot where the pipe passes through the concrete slab receives a heavy seal. Our team makes sure these airtight seals are flawless, because a tiny leak in the indoor piping could let radon seep right back in.
3. The inline radon fan
The continuous fan acts as the beating heart of the mitigation system. We mount it completely outside the living space, usually placing it in the attic, out in the garage, or directly on an exterior wall. That exterior placement guarantees the interior pipe is always under negative suction, so any small leak pulls indoor air in rather than pushing toxic radon out. Our technicians use trusted, energy-efficient models like the RadonAway RP145 because they pull about 40 to 70 watts and only cost around $60 to $100 per year to run.
4. Roofline discharge
The final section of pipe ends securely above the roofline. We follow current EPA guidelines, which dictate that this discharge point must sit at least 10 feet away from any operable windows or doors. This spacing ensures the concentrated radon gas mixes into the open outdoor air immediately without re-entering the building. Our crews will never discharge the gas near a ground-level window or a patio door, as that violates national safety codes.
5. The U-tube manometer
A simple visual gauge called a manometer sits on the PVC pipe. We install this U-shaped tube and fill it with a colored, non-toxic liquid. As explained in the guide on reading your manometer, the liquid sits noticeably higher on one side when the fan is pulling suction. Our goal is to position this gauge in a highly visible spot so you can instantly verify your system health at a single glance.
6. Labels and sealing
The ANSI/AARST national standards require warning labels every 10 feet along the exposed piping to prevent someone from accidentally cutting into it. We label every completed system with the installer information, the activation date, and a clear system warning. Key foundation openings like the sump pit, large cracks, and gaps around existing plumbing pipes also receive a heavy layer of caulk. Our thorough sealing job supports the system suction pressure but never replaces the need for the active fan.
In one sentence
A sealed pipe and a continuously running fan pull radon from under your slab and send it safely above the roof. We include a visible manometer gauge so you always know the equipment is working.
Pressure Field Extension: Making Sure Suction Reaches Everywhere
A single suction point only works if the vacuum pressure spreads completely under the entire concrete slab. We test this carefully because the underlying soil composition heavily dictates how far the air can move. Clean gravel lets air move easily and quickly. Our most challenging jobs happen when tight clay or a slab poured right on top of plain dirt makes creating a vacuum much harder.
Technicians verify the suction reach by drilling small, half-inch test holes in the furthest corners of your basement slab. We measure the air pressure at those distant holes using a highly sensitive digital micro-manometer. This pressure field extension (PFE) test can detect pressure drops as tiny as 0.001 inches of water column. Our team will recommend a larger main pit, a stronger fan model, or an entirely separate second suction point if those far corners lack sufficient suction.
When one suction point isn’t enough
Complex foundations routinely require multiple suction points to achieve safe radon levels. We created the table below to outline the most common structural hurdles and how to solve them.
| Situation | Why it is harder | Typical answer |
|---|---|---|
| Large footprint | Suction has to travel farther | Second suction point |
| Tight clay under slab | Air moves slowly through dense soil | Larger pit or stronger high-suction fan |
| Split-level or additions | Separate slabs are not connected | Suction point on each distinct slab |
| Basement plus crawlspace | Two different foundation types | Membrane in crawlspace tied into the system |
| Drain tile around footings | Can help air move or leak suction | Sump-based suction with a bolted, sealed lid |
What About Sumps and Crawlspaces?
Sumps and crawlspaces require special sealing techniques to prevent them from acting as massive vacuum leaks. We secure these areas so the fan pulls gas from the soil rather than conditioned air from your basement.
Securing the Sump Pit
An open sump pit acts as both a direct radon entry point and a major system leak. Our crews cover these pits using a specialized bolted lid that still allows you easy access to service the water pump. This securely sealed sump actually functions perfectly as the primary radon suction point for many homes. We explain this specific setup in detail inside the guide to sump pits and radon.
Sealing Exposed Crawlspaces
Dirt crawlspaces require a totally different approach since they lack a solid concrete slab to trap the gas. Our team uses a technique called sub-membrane depressurization for these exposed floors. A heavy, 12-mil high-density polyethylene plastic membrane gets rolled over the entire dirt surface and glued securely to the foundation walls. We then draw the suction safely from directly underneath that thick plastic barrier. The full installation process is covered in the article on crawlspace radon mitigation.
Safety Checks During Installation
A proper installation must include mandatory safety checks to protect your home’s air quality and electrical systems. We perform these final audits to ensure everything runs safely and efficiently for years. The current ANSI/AARST SGM-SF-2023 national standard dictates exactly how single-family mitigation systems should be completed. Our certified technicians follow these strict guidelines to the letter. The final walkthrough always includes three specific mandatory safety tests.
- Backdraft testing: We check homes with a gas furnace, water heater, or other fuel-burning appliance to ensure the radon fan does not pull carbon monoxide back down the chimney. The mitigation vacuum must never overpower your existing venting systems.
- Electrical safety: Our electricians hardwire the fan with a weather-rated connection. The building code also demands a dedicated disconnect switch placed right next to the exterior fan box.
- System labeling: We apply clear, highly visible warning labels to the PVC pipe, the manometer gauge, and the fan housing. Future contractors or homeowners can instantly tell what they are looking at and who to call for service.
How Well Does It Work?
An active sub-slab depressurization system is incredibly effective at eliminating dangerous soil gases. We routinely see these setups lower high readings by over 90% within just 24 hours of activation. A properly designed SSD system brings US homes from well above the 4.0 pCi/L danger zone down to below 1.0 pCi/L.
Our local installations have achieved up to a 98.9% reduction in residential properties. An independent post-mitigation test always confirms this final result. We back every job with a 5-year warranty that covers further adjustments if needed, which you can verify in the guide on do radon mitigation systems really work?
The process of getting started is incredibly straightforward. Our team asks you to send the office some clear photos of your basement and the exterior walls to get started. A technician will review the images to suggest the best suction point location, pipe route, and fan placement. We will then provide a firm, flat-rate price before anyone ever visits your driveway.