If your test came back at 4 pCi/L or higher, a mitigation system is the fix. Most Duluth homes are done in a single day for $1,500 to $3,000, and the result is verified with a follow-up test — not assumed.
A radon mitigation system is a sealed pipe, a continuously running fan, and a suction point beneath your foundation. It costs $1,500 to $3,000 installed in Minnesota, goes in during a single visit for most houses, and reliably takes a home from a high reading down under 2 pCi/L. It is one of the few serious problems a house can have that is permanently solved by a one-day project.
If you are here because a test came back high, the short answer is that you are not in trouble and you do not need to make a decision today. Radon risk is cumulative over decades, not acute. What you need is an installer who will look at your actual foundation, tell you which of the three system types your house calls for, quote a real number, and prove the system worked with a measurement afterward. That last part is where most of the difference between contractors shows up.
If you have not tested yet, start there. System design depends on the number — a 5 pCi/L house and a 28 pCi/L house get different fans and sometimes a different number of suction points. Our radon testing page in Duluth covers short-term versus long-term measurement and why a January reading and a July reading on the same house can differ by a factor of three.
The one thing to check on any quote: does it include a post-installation confirmation test? A system that has never been measured after startup is an assumption, not a result. Call (218) 520-9679 and we will walk your foundation and give you a number.
The physics is simpler than most homeowners expect, and understanding it makes every other decision easier.
Your house runs at slightly lower air pressure than the soil beneath it. Heated air rises, escapes through the upper floors and attic bypasses, and the air that replaces it gets pulled in low — a good share of it straight out of the ground through the floor-wall joint, block wall voids, slab cracks, and the sump pit. That pressure difference is the stack effect, and it is the engine driving radon into the building. In Duluth, with a heating season that runs most of the year, that engine is running for a very long stretch of every twelve months.
A mitigation system does not try to seal every opening. Sealing alone almost never works, because you cannot find and permanently close every crack in a foundation. Instead the system reverses the pressure difference. A fan draws air out of the space beneath your slab and discharges it above the roofline. That makes the region under the foundation lower pressure than your basement. Soil gas still moves, but it now takes the path of least resistance, which is the pipe. Air actually flows down through the small cracks that used to be entry points, rather than up through them.
This is why the fan runs continuously and why it must never be shut off in winter. It also explains why a well-designed system is nearly silent, uses about as much electricity as a light bulb, and does not meaningfully raise your heating bill: it is pulling soil gas from beneath the slab, not conditioned air out of the house.
Which system your house gets is determined by what is under the floor, not by preference. In practice, one of these three covers essentially every Duluth home.
Sub-slab depressurization is the standard and the most common. A hole is cored through the basement slab, a pit is excavated in the material underneath, and a PVC pipe is sealed into that opening and run to a fan and out above the roof. The pit gives the fan a volume to draw from so suction spreads laterally under the whole slab.
Drain tile suction is used where the house already has an interior drain tile loop running to a sump. Instead of coring the slab, the suction point ties into that loop, and the sump gets an airtight lid with a sealed gasket and a clear inspection port. Drain tile is a pre-built distribution network right at the footing, so when it exists this is usually the cheapest and most effective option available. It only works with an interior loop — exterior drain tile that daylights out the side of a hill does not give the fan a closed path.
Sub-membrane depressurization is for crawl spaces with exposed dirt floors, which show up constantly in Duluth's pre-1950 housing. Heavy plastic sheeting is laid over the soil, sealed at the seams and up the foundation walls, and a suction point is placed beneath it. The membrane becomes the floor the system depressurizes. Our crawl space radon mitigation page covers the sheeting, sealing details, and access problems in depth.
| System type | Used when | House type | Relative cost |
|---|---|---|---|
| Sub-slab depressurization | Full basement slab, no usable interior drain tile | Most Duluth homes with a poured or block-wall basement | Baseline — middle of the $1,500–$3,000 range |
| Drain tile suction | Existing interior drain tile loop discharging to a sump | Homes with a sump pit, often post-1970 or retrofitted | Lowest — no slab coring, sump lid included |
| Sub-membrane depressurization | Exposed soil under a crawl space | Older hillside homes, additions, partial crawls | Highest — labor for sheeting and sealing |
| Combination system | Basement slab plus a separate crawl or addition slab | Homes expanded over time with disconnected foundations | Above baseline — two suction points, one fan if pressures allow |
The single biggest variable in a mitigation quote is something you cannot see: what the builder put under your slab.
If there is four to six inches of clean, washed gravel down there, air moves through it easily. One suction point in the middle of the basement can pull a measurable vacuum across the entire slab, and a standard fan handles the whole house. If instead the slab was poured over compacted clay, native till, or construction fill — which is common in older Duluth construction and in hillside lots where the pad was cut and backfilled — airflow is choked. Suction dies out a few feet from the pit, and the far corners of the basement never see the pressure reversal at all.
A qualified installer settles this with a diagnostic communication test before designing the system rather than guessing. A test hole is drilled at the proposed suction location and one or more small holes are drilled at the far edges of the slab. A vacuum is applied at the test hole, and a micromanometer measures whether any pressure difference shows up at the distant holes. Good communication means a single point will serve the slab. Weak or no reading at the perimeter means the house needs two or three points, a higher-suction fan, or both.
This matters to you as a buyer of the service because it is the honest explanation for why two houses on the same block get quotes $700 apart. Anyone quoting a Duluth basement sight-unseen, at a flat price, without asking about gravel, drain tile, or additions, is pricing an average rather than your house.
Generic radon advice assumes a rectangular ranch on flat ground with a poured basement. Duluth's housing stock does not cooperate with that assumption, and the differences are the reason local experience matters here.
Hillside walkouts and daylight basements. A huge share of homes above the lake have foundations cut into rock and backfilled on the uphill side while the downhill side is exposed. That means more foundation-to-soil contact on one side, uneven backfill material, and a slab that may sit partly on rock and partly on fill. Suction spreads unevenly across foundations like that, which raises the odds of needing a second point.
Hollow block foundation walls. Standard in pre-1960 Duluth housing. The voids inside concrete block act as a chimney running the full length of the wall, collecting soil gas along the footing and releasing it into the basement well away from the floor. On these houses a slab-only suction point sometimes will not do it, and the block cores themselves have to be depressurized or the top course sealed.
No interior chase. Many older houses simply have no closet or stack running from basement to attic. When that is the case the pipe runs up the outside of the house, painted to match the siding and secured against wind. It is a legitimate design, not a compromise, but it changes the labor and the price.
Additions on separate slabs. A three-season porch converted to living space or a rear addition poured decades after the original almost always sits on its own isolated slab with no airflow connection to the main one. Each disconnected slab needs its own suction point, and that is one of the most common reasons a quote lands at the high end.
The long heating season. Duluth's stack effect runs from roughly October through April. That drives winter readings much higher than summer readings on the same house, and it affects sizing — a system designed around a mild-weather test can be underpowered when January arrives. Design should be based on the highest expected condition, not the most convenient one.
Typical installed cost in Minnesota is $1,500 to $3,000. A house lands at the low end when it has a single poured slab, clean gravel underneath, an interior drain tile loop with a sump to tie into, and a straight interior chase up to the attic. That is a straightforward half-day job with one suction point and a standard fan.
A house lands at the high end when several of these stack up: two or more suction points from poor sub-slab communication, hollow block walls that need their own treatment, a crawl space requiring membrane sheeting, multiple disconnected slabs from additions, an exterior pipe run on a tall or steep-lot house, or a high-suction fan for tight soils. Long pipe runs on three-story hillside homes add material and labor on their own.
Two things that should never be optional line items: the electrical permit and the post-installation confirmation test. If either is missing from a written quote, ask directly why. You can compare bids sensibly through our free estimate request, and we will tell you which of the drivers above apply to your specific foundation.
Once the fan is running, the house needs time to reach a new equilibrium. Standard practice is to wait at least 24 hours after startup before placing the confirmation test, and the test itself typically runs 48 hours under closed-house conditions. Only then do you know what the system actually accomplished.
A quote with no post-installation test is the single clearest warning sign in this trade. Radon is invisible. Without a measurement, neither you nor the installer has any evidence the system worked, and the failure modes are not obvious — a suction point in the wrong spot, a slab with no communication, an unsealed crawl space, or an addition nobody accounted for can all produce a system that looks perfect and barely moves the number. Get the confirmation result in writing and keep it. If you sell the house, it is the document a buyer's agent will ask for.
Reading the manometer. The U-tube holds colored liquid in a U shape. When the fan is off, both columns sit level. When it is running, the vacuum pulls one side up and the other down, and the offset between them is your reading. Note that offset the day the system is commissioned, or take a photo of it. If the columns ever return to level, the fan has failed or the pipe is blocked. If the offset changes noticeably, something in the sub-slab conditions or the sealing has changed.
Fan failure. Radon fans typically last several years of continuous operation and are replaceable without touching the rest of the system. A failed fan usually announces itself as sudden silence, a new rattling or grinding noise, or a level manometer. Replacement is a small job compared to the original install.
Retesting cadence. Retest every two years even with a working system, and additionally after any major foundation work, slab repair, sump replacement, window or siding replacement that tightens the building envelope, or a furnace, water heater, or HVAC change. Anything that alters how the house breathes can alter the pressure balance the system depends on. If you are selling, a current test plus the original confirmation result is exactly the documentation the Minnesota Radon Awareness Act disclosure process expects you to have on hand.
Licensing is not optional here. Minnesota law requires anyone performing radon testing or mitigation in a building they do not own or lease to hold a license from the Minnesota Department of Health. National industry certification alone is not sufficient in Minnesota. Ask for the MDH license number in writing before any work begins — from any contractor, including us.
Beyond the license, a good quote is specific to your house. It should name the system type, state how many suction points and why, identify where the fan goes and where the pipe discharges, include the electrical permit, and include the confirmation test with a written report. Vague flat-rate pricing over the phone, no mention of a diagnostic when the sub-slab material is unknown, a fan proposed for a basement or crawl space, and no post-install test are all reasons to get another bid.
Most residential systems in Minnesota run $1,500 to $3,000 installed. In Duluth the final number comes down to your foundation. A single poured slab with clean gravel underneath, an interior drain tile loop with a sump, and a clear interior route to the attic sits at the low end. Multiple suction points, hollow block walls, a crawl space needing membrane sheeting, additions on separate slabs, or an exterior pipe run on a tall hillside house push it higher. A walkthrough is the only way to get an accurate number.
Most single-family sub-slab systems are finished in four to six hours in one visit. Drain tile suction systems can be faster because no slab coring is required. Crawl space sub-membrane systems usually take a full day, sometimes longer, because the soil has to be covered and every seam and wall edge sealed before the suction point goes in. After the fan starts you wait at least 24 hours before placing the confirmation test, and that test typically runs another 48 hours.
Because of what is under the slab. If the builder used clean gravel, air moves freely and a single suction point can pull a vacuum across the entire floor. If the slab was poured over compacted clay, native till, or fill, suction dies out within a few feet and the far corners never see any pressure reversal. A diagnostic communication test settles it: a vacuum is applied at the proposed point and a micromanometer checks for pressure at the slab perimeter. Additions on separate, disconnected slabs also each need their own point.
No. The fan must go in an unconditioned space such as an attic, an attached garage, or outside on the exterior pipe run. The reason is straightforward: everything downstream of the fan is under positive pressure, so if a joint or fitting ever develops a leak, it would push concentrated soil gas directly into whatever space it sits in. Putting a fan in a basement, crawl space, or any living area is a serious installation error and a reason to reject a bid outright.
Read the U-tube manometer on the pipe. When the fan runs, the vacuum pushes the colored liquid off level, and the offset between the two columns is your indicator. Record or photograph that offset when the system is commissioned. If the two columns ever sit level again, the fan has failed or the pipe is blocked, and the system is not protecting the house. Beyond the manometer, retest with an actual radon measurement every two years, since a running fan is not by itself proof of a low level.
Yes, twice over. A confirmation test at least 24 hours after startup is how you learn whether the system worked at all, and any quote that omits it should be questioned. After that, retest every two years, and also after major foundation or slab work, a sump replacement, or any furnace, water heater, or HVAC change. Work that tightens the building envelope, such as new windows or siding, can also shift the pressure balance the system depends on and is worth a retest.
No. Minnesota requires a license issued by the Minnesota Department of Health for anyone performing radon testing or mitigation in a building they do not own or lease. National industry certification is a credential, not a substitute for that license, and a contractor holding only certification is not legally permitted to do the work here. Ask for the MDH license number in writing before work starts, and confirm the finished system carries a permanent label with the installer's information and the installation date on it.
We will look at your foundation, tell you which system type it calls for and how many suction points it needs, and quote it with the permit and confirmation test included. No obligation.