When you actually need a radon mitigation system
If a test came back at 4.0 pCi/L or higher, mitigate. That is the EPA action level, it is not a soft recommendation, and in Delaware County it is a threshold the average home is already sitting on.
Between 2.0 and 3.9 pCi/L, EPA says to consider it, and this is where the honest conversation happens. There is no established threshold below which radon is harmless. The risk curve doesn’t have a cliff, it has a slope. But the slope at 3.3 is genuinely flatter than at 8.0, and pretending otherwise to sell a system is exactly the behavior that makes people distrust this industry.
Three things push a mid-range reading toward “fix it”:
- Somebody lives down there. A finished basement bedroom, home office, or rec room turns an abstract average into hours of daily exposure at the highest-concentration point in the house.
- You tested in warm weather. Muncie closed-house winter readings routinely come in above the same home’s summer number. A 3.3 in July is not the same as a 3.3 in January.
- You’re selling within a couple of years. Mitigating on your schedule costs the same as mitigating under a two-week closing deadline, minus the leverage the buyer would otherwise have.
Below 2.0 pCi/L, retest every two years and move on with your life.
- Soil gas. Radon from decaying uranium migrates up through permeable glacial till toward the foundation, which is the lowest-pressure thing above it.
- Suction pit. A single core hole through the slab, with a void excavated in the aggregate beneath so the fan draws from a plenum rather than a straw.
- Sealed pipe. Schedule 40 PVC, sealed at every joint and pitched so condensate drains back toward the pit.
- Fan, outside living space. Mounted in the attic or on an exterior wall. Everything downstream of the fan is under pressure, so a leak there would push radon into the house. That is what the placement rule prevents.
- Discharge above the roofline. Terminated above the roof and away from windows so nothing re-enters.
- Sealed sump and joints. An airtight sump lid and sealed floor-to-wall joints. Sealing is not the mitigation, the fan is, but an open sump short-circuits a correctly sized system.
- Manometer. The U-tube gauge. Uneven liquid means the system is pulling. Level liquid means it is not.
Not to scale. Basement and slab-on-grade homes both use this approach; crawl spaces need a sub-membrane system instead.
System types, matched to Delaware County foundations
Almost every residential radon system is a variation on one idea: depressurize the soil under the house so gas flows into a pipe instead of into your living room. Which variation you need is decided by what your house sits on.
Sub-slab depressurization (basements and slab-on-grade)
The standard system, and what most Muncie homes get. It is the one drawn above: suction drawn from a pit beneath the slab, sealed pipe to a fan outside conditioned space, discharge above the roofline.
Sub-membrane depressurization (crawl spaces)
A crawl space has no slab to depressurize, so the floor gets one: heavy-gauge reinforced liner sealed to the foundation walls and around every pier, with a suction point drawn from underneath it. It costs more than a slab system because most of the labor is hand-work in a three-foot space. A large share of Delaware County housing sits on crawl spaces, so this is not the exotic case here. Details on the crawl space radon page.
Combination and multi-point systems
Additions, split-levels, and houses where a slab section meets a crawl space usually need both approaches tied into one fan, or two suction points manifolded together. Older Muncie housing stock produces this more often than newer subdivisions do.
Before the quote: the diagnostic
The diagram above shows the finished system. The step it cannot show is the one that decides whether the system works: a pressure-field extension test, which measures how far suction actually travels under your specific slab given whatever material is down there. That measurement is what determines one suction point or two, and it should happen before a number is written down rather than discovered on install day.
On the day itself, expect one core hole rather than demolition. Concrete dust is contained, and the hole is patched and sealed the same day.
What it costs in Muncie, and what moves the number
| Source | Figure | What it describes |
|---|---|---|
| Indiana state radon fact sheet | $800 to $1,200 | Stated average install for the state, describing the easiest possible job |
| Local market pricing, Delaware County | $1,200 to $2,000 | What a typical single-family quote here actually looks like |
A straightforward basement or slab job with one suction point sits at the low end. Crawl space systems run higher because of the membrane labor. Replacing a fan on an existing system costs a fraction of a new install, since the pipe and routing are already there.
The variables that move you within that range:
- Foundation type. Crawl spaces cost more because of the membrane labor, not because the physics is harder.
- Footprint and soil. A 2,600 sq ft slab over tight clay may need a second suction point that a 1,200 sq ft slab over gravel never will.
- Pipe routing. An interior route through a garage and out the roof is cheaper and better-looking than a long exterior run up two stories of siding.
- Fan sizing. Static pressure requirements drive fan selection, and the right fan is the one that matches your soil, not the biggest one on the truck.
Ask any company you call for their range before they visit. The ones that refuse are telling you something.
Timeline and what living with a system is like
Most Muncie installs are one day, typically four to six hours. Crawl space membrane jobs and multi-suction systems can run into a second day, and you will know which one you are before work starts rather than after.
Once it is in, the system runs continuously and you will mostly forget it exists. A correctly installed fan mounted outside is a low hum you notice from the driveway and not at all from inside. Figure roughly $5 to $10 a month on the electric bill. Maintenance is glancing at the manometer once a season and replacing the fan at around year ten.
The retest is the part that matters
An installed system that nobody verified is a decoration. Every job should end with a post-mitigation test showing a result under the 4.0 pCi/L action level, and a correctly designed system should land well below it.
If it does not come down, the fix is diagnosis rather than a second system: usually an unsealed pathway, an undersized fan, or a slab section outside the suction field. Hold any contractor to finishing that diagnosis, including anyone we route you to.
Keep the document. When you sell, it is the difference between “there’s a system” and “here is proof it works.”
Building new? Make it radon-ready instead
If you are building in Delaware County, passive radon-ready rough-in during construction costs a few hundred dollars: a gas-permeable aggregate layer, a sealed vapor barrier, a capped vertical pipe from below the slab up through the roof, and a junction box in the attic. If the finished house tests high, activating it means adding a fan to a pipe that already exists, which costs a fraction of a retrofit.
In a Zone 1 county, this is the cheapest insurance in the entire build. Ask your builder before the slab is poured, because afterward the conversation becomes a retrofit conversation.
Not sure whether you need this yet?
If you do not have a number, start with radon testing, because it is the only input that matters. If you are mid-transaction and an inspection just came back high, the real estate radon page covers timelines, who pays, and how to keep a closing on schedule.
Frequently asked questions
What kills radon gas?
Nothing does, and any product claiming to is worth walking away from. Radon is a radioactive element, so it cannot be neutralized, filtered out chemically, or "killed." It decays on its own schedule (radon-222 has a half-life of about 3.8 days) and nothing you buy changes that.
What works is removal: a mitigation system intercepts the gas in the soil under your slab and vents it outside before it enters your living space. Air purifiers, HEPA filters, ozone generators, and houseplants do not meaningfully reduce radon.
Can I install my own radon mitigation system?
In Indiana the IDOH certification requirement applies to people offering radon services to others. A homeowner working on their own house is a different situation, and worth confirming against current IDOH rules before you start. The more useful question is whether a DIY system works.
The failure modes in DIY and flip-house systems are consistent: an undersized fan that cannot overcome the soil's static pressure, a single suction point on a slab that needed two, an unsealed sump pit that short-circuits the whole system, and a discharge point too close to a window. Each one produces a system that hums along looking correct while the number barely moves. If you do install your own, the non-negotiable step is a post-install test. If the number did not come down, our system repair page covers what to check.
How much does a radon fan cost to run?
A typical residential radon fan draws roughly 40 to 90 watts and runs around the clock. That works out to roughly 30 to 65 kWh a month, which at typical Indiana residential rates lands somewhere around $5 to $10 a month. Check your own rate per kWh if you want the exact figure for your bill. There is a second, smaller cost people forget: the fan pulls a little conditioned air out with the soil gas, so heating and cooling costs tick up slightly. A correctly sized system keeps that minimal, whereas an oversized fan wastes energy without buying additional radon reduction.
How long does a radon fan last?
Plan on about 10 years. These are sealed, continuously running motors mounted outdoors in Indiana weather, and they fail quietly: the house refills with radon over the following weeks and nothing tells you unless you look at the manometer. Warranty terms vary by manufacturer, so check the label on your own fan.
Check the manometer (the U-shaped gauge on the pipe) once a season: if both columns of liquid sit at the same level, the system is not pulling. See radon fan replacement.
Why are my radon levels higher in the winter?
Two reasons stack in an Indiana winter. First, the house is closed, so no open windows are diluting indoor air. Second, the stack effect gets stronger: warm indoor air rises and escapes at the top of the house, which pulls replacement air in at the bottom, and some of that replacement air comes straight out of the soil through your foundation.
This is why a July test result can meaningfully understate your exposure and why winter is peak testing season in Delaware County. A 3.1 in summer is worth re-checking in January.