Most homeowners treat a radon mitigation system like a furnace filter. You install it, figure it works, and forget it. Radon doesn’t play by those rules. It changes with seasons, with your home’s weatherization, with renovations, and with the slow aging of materials and fans. A good system keeps levels low for years, but performance drifts. Upgrades sometimes become the difference between a safe basement and a problem that creeps back while no one is looking.
I’ve worked on hundreds of systems, from tidy new builds in the suburbs to stone-foundation homes that date back before indoor plumbing. The best approach is always case-by-case, yet I see consistent triggers that tell me it’s time to revisit the design or components. This guide explains how to recognize those triggers, what kinds of upgrades make sense, and how to weigh cost, disruption, and risk. If you’re looking for help locally, searching “radon mitigation near me” is a good start, but it helps to know the right questions to ask a radon mitigation contractor before you make changes.
What changes over time
A radon mitigation system depends on small pressure differences and a clear path for air. You do not need much airflow to transport radon away from the soil beneath a slab, but you do need stability. The soil dries and compacts. Sump pits are sealed, then resealed. A finished basement adds walls and tight doors. An attic fan is installed and changes building pressure. Trees near the home mature and shade the roof, which changes condensation patterns in vent piping. Each small change reduces your system’s margin of safety.
The fan is also a consumable part. Most inline radon fans last 7 to 12 years, some longer if conditions are kind. Bearings wear. Impellers collect dust and frost. The vibration mounts sag. A weakening fan may keep the manometer looking normal while your long-term average creeps up.
Even the way we live changes the risk picture. Many of my clients started working from home and spent twice as much time in the basement office as they did five years ago. Time-weighted exposure matters, and an upgrade designed for a lower-use space may no longer fit how the space is used.
When should you re-test before you upgrade
Before making any change, get data. A single short-term test can be misleading, especially during transitional seasons. I recommend a two-step approach that has saved more than one client from replacing a perfectly good fan:
- Run a continuous radon monitor for at least 7 to 14 days to see daily swings, then follow with a 90-day (or longer) test during the heating or cooling season when your house is closed.
If you’re in St. Louis or the surrounding counties, the soil profiles and housing stock mean winter tests often read higher than summer. The metro’s karst geology and river valleys create local hot spots. Companies that know St. Louis radon patterns, sometimes branded as STL Radon or St Louis Radon specialists, tailor testing windows to those microclimates. Good data shows you whether a system has genuinely drifted or if your last number was seasonal noise.
Clear signs it’s time to consider an upgrade
One homeowner I worked with had a steady 1.6 pCi/L for years, then a steady climb to 3.2, then 4.8. The fan sounded fine and the U-tube still showed a pressure difference. The culprit turned out to be a new tight basement door and a carpet pad that choked the path along the slab edge. We added a secondary suction point and replaced the fan with a slightly higher flow unit. The level dropped to 0.9 and stayed there. Patterns like that repeat across many houses.
Here are the most common upgrade signals I see, especially for those calling about radon mitigation St Louis wide:
- Long-term average drifting above 2.0 pCi/L after a period of stability, or short-term tests repeatedly above 4.0 pCi/L. Audible changes in the fan (rattling, whining) or a manometer reading that has noticeably shifted from its long-standing baseline. Renovations that tighten the envelope, add sump lids, or partition spaces, and finished basements that introduce barriers between open slab areas. Water intrusion events that saturate sub-slab fill or crawlspace soils and change permeability, which the system was not designed to overcome. Frosting or condensate leaks on vent piping, often a sign of poor routing, lack of insulation in cold spaces, or marginal slope.
Anyone searching “radon mitigation system help” or “radon system not working” will find checklists that focus on quick fixes. Those help, but upgrades often involve multiple small corrections that together restore a good safety margin.
What “upgrade” actually means
Upgrades cover a spectrum from swapping a tired fan to redesigning how the system collects air. It is not always about buying the most powerful fan on the shelf. Oversizing can drive noise, raise energy use, and in rare cases backdraft atmospherically vented combustion appliances. Skill lies in matching the fan curve to the sub-slab permeability and the piping friction, then keeping condensate moving in the right direction.
The most common and effective upgrades include:
- Replacing the fan with a right-sized, more efficient model. Modern EC-motor fans use less electricity and run cooler. A typical radon fan draws 50 to 120 watts, so the difference can add up over 24/7 operation. Adding a secondary suction point, especially for larger basements or homes with additions and thick interior footings that split the slab into zones. Reworking vent routing to achieve proper slope for condensate, reduce elbows, and move the discharge away from windows, soffit intakes, or the neighbor’s deck. Sealing overlooked pathways, such as plumbing gaps, cold joints, and the sump basin lid. Airtightness at these points improves pressure under the slab where it matters and reduces the risk of drawing conditioned air from the living space. Introducing sub-membrane depressurization in crawlspaces, which are a frequent source of persistent radon despite a well-performing slab system in the main basement.
I’ve also specified quiet enclosures, vibration isolators, and outdoor-rated fans when noise or aesthetics become a barrier to keeping a system running.
The right time to plan an upgrade
Tying upgrades to other home projects often saves effort and avoids rework. If you are finishing a basement, run a quick radon test before you close walls. If you are insulating or air-sealing, test right after. If your HVAC contractor is swapping equipment, coordinate to confirm that the radon system will not cause backdrafting. I have seen a new tightly sealed water heater closet and a more aggressive radon fan pull flue gases back into the home. A simple combustion safety test, plus a modest tweak to fan selection or make-up air, prevents it.
In older St. Louis homes with fieldstone foundations, plan for radon work alongside tuckpointing or drain tile projects. These structures can be tamed, but the pathways are more complex and a radon mitigation contractor with local experience will anticipate the oddities you cannot see from a listing photo.
Making sense of the fan choice
Many homeowners ask for the “strongest” fan. That is not the right request. You want the fan that delivers sufficient pressure and flow without unnecessary noise, power use, or condensation issues. Sub-slab conditions matter more than square footage. A 1,200 square foot slab with tight, clay-rich soil can need more suction than a 2,500 square foot slab over clean gravel.
If you have a two- or three-story vent run, make sure the fan is rated for the static pressure you expect at that height, and that the pipe is sized to keep velocity reasonable. I see too many systems with undersized pipe and long vertical runs that whistle like a flute on windy nights. Upgrading to a larger diameter pipe during a fan swap can reduce friction and noise while allowing a smaller, quieter fan to do the same job.
Red flags in existing installations
Not every house needs upgrading, but certain installation patterns almost always benefit from a rethink. Watch for fans mounted in living spaces, discharge points below a soffit vent, and vents that terminate too close to a window. Also be wary of piping that runs horizontally in attics without slope for condensate. Water will collect, freeze in winter, and either block air or drain backward into the fan. Fixes here are often inexpensive and give immediate performance gains.
Another frequent issue is systems that rely on a single suction point in a complex slab layout. You might see a good manometer reading and a low radon level in milder weather, then spikes when the soil saturates. Adding a second suction point in a wing of the house evens out pressure in wet seasons.
How tightness and ventilation interact with radon
Air sealing lowers energy use and improves comfort, but it also changes pressure relationships. A sealed basement rim joist and spray-foamed band board can reduce natural infiltration that was diluting radon near the slab. If you have made your home tighter, your mitigation system now carries more of the load. That does not mean you should avoid air sealing. It means the radon system may need a small boost, like a fan with a deeper pressure capability or an added suction point.
Balanced ventilation helps. ERVs do not “fix” radon the way sub-slab systems do, but they can reduce peaks, especially in a tight home where stale air lingers. I have used ERVs as a complement in homes with persistent but low radon, or as a comfort and moisture control upgrade when we are already opening walls. However, do not rely on an ERV alone if your baseline is well above 4.0 pCi/L. Source control under the slab remains the primary tool.
Weather and seasonal swings
In the St. Louis area, winterstack effect pulls air from the lower parts of the house upward, which can increase soil gas entry if the slab is not well detailed. Homes with radon mitigation often see their levels rise in January and fall in Radon mitigation system June. That pattern is normal, but the amplitude tells a story. If your winter peaks used to sit around 1.8 pCi/L and now hit 3.5, the system’s breathing room is gone. An upgrade can restore the margin so that even on the worst days you are well below 4.0 and, ideally, below 2.0.
Spring flooding or simply a high water table after extended rain will change sub-slab permeability. I have watched manometers shift by half an inch of water column during wet weeks. If your system was designed near the edge of its capacity, those swings push you past the line. Adding suction points or modestly upsizing the fan gives resilience against wet soil.
Noise, aesthetics, and neighbor considerations
People tolerate more noise than they should because they think mitigation has to be loud. It doesn’t. Fans can be selected for low tonal noise, mounted in the attic or outside with vibration isolators, and routed to terminate well above the roofline where sound dissipates. I once moved a fan from a basement utility room to the garage attic for a musician who recorded at home. We kept the same radon performance and dropped the noise in the studio by more than 10 dB.
Aesthetics matter too. White PVC snaking across a dark brick facade will always catch the eye. Rerouting along a side elevation, using paintable pipe, or running internally to the attic are options that, when planned with a competent radon mitigation contractor, can bring both safety and curb appeal. In dense neighborhoods, placing the discharge to avoid a neighbor’s second-story window is not just kind, it prevents complaints that lead some homeowners to shut systems off.
Cost ranges that reflect reality
Pricing varies by region and the particulars of the house, but a few ballparks help planning. A basic fan replacement runs a few hundred dollars for the part and another few hundred for labor, often totaling $700 to $1,200. Add a new suction point and some concrete coring, and you might see $1,200 to $2,000. Complex redesigns that include crawlspace membranes, multiple suction points, and long vent runs can reach $3,000 to $5,000. Energy use for a typical radon fan lands between $50 and $200 per year depending on local rates and fan draw.
These numbers often beat the cost of healthcare that comes with long-term exposure. I have had tough conversations with families who discovered very high levels only after a sale failed. Far better to keep the system current and keep your documentation tidy.
Documentation, warranties, and building codes
Upgrades are a good time to bring the system up to current standards if it predates your local code or ASTM/ASHRAE guidance. This might include labeling the piping, adding a service switch near the fan, ensuring electrical connections are properly enclosed, and upgrading discharges to the right height relative to the roof. In some municipalities, including parts of the St. Louis region, there are explicit clearance rules for radon vent terminations. A reputable company working under the St Louis radon market norms will know these details.
Keep copies of test results before and after the upgrade, the system sketch, and the model number of the installed fan. If the house goes on the market, this paperwork helps buyers trust the system. Many fan manufacturers offer warranties in the 5-year range, and some contractors add workmanship guarantees. These are only as good as your records and the installer’s solvency, which again argues for hiring a stable, locally known pro rather than a lowest-bid outfit that does a dozen trades on the side.
DIY tweaks versus professional redesign
I am not against homeowner maintenance. Replacing a cloudy manometer, tightening a sump lid, and resealing visible slab cracks with a high-quality polyurethane sealant are all reasonable homeowner tasks. If the fan has an external plug and isolation switch, a capable homeowner may swap it safely, but check electrical codes and your comfort level. Any work that involves routing new vent piping, coring concrete, or penetrating fire-rated assemblies should be handled by a licensed radon mitigation contractor.
When you look for help, “radon mitigation near me” will return a mix of local specialists and HVAC or waterproofing firms that also offer radon. Ask for recent measurement data from similar homes, confirm they perform post-upgrade testing, and press for specifics on how they choose fan sizes. If the answer is “we just use the biggest one,” keep looking.
How to think about targets and safety margins
The EPA action level of 4.0 pCi/L is not a magic line between safe and unsafe. It is a policy trigger developed with feasibility in mind. The World Health Organization recommends a reference level of 2.7 pCi/L. I counsel homeowners to aim for long-term averages below 2.0 if practical, with winter peaks that still stay comfortably under 4.0. When upgrading, I design for that margin rather than to barely meet the action level. Systems that run near their limit tend to become problem cases after the next home project or wet season.
In many of the St. Louis radon upgrades I’ve overseen, getting from 2.8 down to 1.3 took a second suction point and a better fan, not a whole-house overhaul. In other cases, lifting old carpet, sealing a gap behind a stair landing, and fixing condensate slope netted a full point of reduction with the original fan.
Special cases: slab-on-grade, split levels, and crawlspaces
Slab-on-grade homes often have fewer easy routing options for piping. Upgrades here focus on optimizing the suction point and paying close attention to perimeter sealing and control joints. Split-level homes sometimes need separate suction zones because the soils under each slab are not well connected. Crawlspaces require membranes sealed to the walls with butyl tape and mechanical fasteners, then a suction system similar to a slab. I have seen homeowners try to vent a crawlspace with a box fan and a plastic sheet taped to the dirt. That is not mitigation. Properly installed sub-membrane systems are steady performers, and adding one as part of an upgrade often solves stubborn cases.
Moisture, mold, and radon: a three-way problem
A mitigation system can dry the sub-slab region and, by reducing entry, indirectly reduce basement humidity. But sometimes a stronger radon fan draws more humid air from the soil perimeter if seals are weak. If your upgrade coincides with a rise in basement humidity, revisit sealing at the slab edge, sill plate, and sump. I have used small, sealed mechanical ventilation in combination with a dehumidifier to balance the space after a fan upgrade. Think of the basement as an ecosystem. Change one pressure, and others shift.
What to ask during an upgrade consultation
Use your first call with a contractor to test for fit. The right expert should be able to talk through your home’s specifics without leaning on generic promises. A short, focused checklist helps:
- What were my previous and current long-term results, and what margin are you designing for? Will you measure sub-slab communication before choosing the fan and number of suction points? How will you route and slope the vent to manage condensate, and where will it terminate to meet local clearances? What post-upgrade testing do you include, and how soon after the work? If the initial upgrade does not reach the target, what is the next step and likely cost?
Professionals who serve the radon mitigation St Louis market are used to these questions. The good ones welcome them because the answers distinguish careful design from guesswork.
Case notes from the field
A brick ranch west of the city had a single suction point and a decade-old fan. Long-term averages crept from 1.9 to 3.4 pCi/L. The attic vent run had two flat spots filled with water. After replacing three elbows with long-sweep fittings, raising the pipe by four inches to restore slope, and upgrading to a slightly stronger, quieter fan, the level dropped to 1.2. No extra suction point was needed.
A split-level in South County sat over mixed fill. The front slab communicated poorly with the rear. The original contractor had simply installed a big fan that howled on windy nights. We split the system into two modest suction points, reduced pipe velocity with a larger riser, and used a balanced fan pair on a single discharge. The home now sits at 0.8 to 1.0 year-round, and the homeowner no longer shuts the system off to get some quiet.
A historic home near the river combined a partial basement with a crawlspace. The slab side tested okay but spikes persisted in wet weather. We added a reinforced membrane in the crawl, taped and sealed to the stone walls, and tied it into the existing system with a dedicated branch and damper. The combination stabilized the whole house under 1.5 pCi/L even in spring floods.
Putting it together
A radon mitigation system is not a fixed appliance. It is a small engineering solution working against a living, shifting set of conditions. Upgrades are not admissions of failure, they are routine stewardship. When the data starts to drift, or when your home changes, it is time to evaluate.
Call a qualified radon mitigation contractor, especially one accustomed to local soils and building styles. If you are in the region, a search for radon mitigation St Louis or St Louis radon will surface teams that know the local norms and code details. Ask pointed questions, set targets below 2.0 pCi/L when practical, and make choices that build margin, not just compliance.
If you treat the system as part of the house, not an afterthought, the upgrades will be straightforward, the cost predictable, and the payoff clear. A quiet fan, dry piping, sound seals, and measured performance together give you what you wanted on day one: confidence that the air in your home is safe, every season, every year.
Air Sense Environmental – Radon Mitigation & Testing
Business Name: Air Sense Environmental – Radon Mitigation & TestingAddress: 5237 Old Alton Edwardsville Rd, Edwardsville, IL 62025, United States
Phone: (618) 556-4774
Website: https://www.airsenseenvironmental.com/
Hours:
Monday: 9:00 AM – 5:00 PM
Tuesday: 9:00 AM – 5:00 PM
Wednesday: 9:00 AM – 5:00 PM
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Radon is an odorless and invisible radioactive gas that can accumulate indoors. Testing is the only way to determine radon levels and protect your household from long-term exposure risks.How long does a professional radon test take?
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Southern Illinois University Edwardsville (SIUE)A major public university campus that serves as a cultural and educational hub for the Edwardsville community.
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