Buying a new house often comes with assumptions about safety and modern building standards. You might notice a white PVC pipe in your basement and assume your indoor air is protected.
That pipe is just a starting point.
Our team frequently encounters homeowners who mistakenly believe this basic venting handles everything. The reality is that these built-in setups are rarely enough to combat the heavy soil gases found across the state. If you are comparing a passive vs active radon system, you are asking the right question.
This guide explains the practical steps for activating a passive system and precisely when it becomes necessary. Let’s examine the 2026 requirements, look at the actual performance data, and explore how to fix high test results.
What Is a Passive Radon System?
As of July 2026, Iowa’s HF 2297 law requires every new single-family and two-family home to include radon-resistant construction. Builders must install a passive rough-in before the walls are closed up. This legislation provides the essential physical infrastructure, but it intentionally leaves out the most critical component.
A standard passive system includes a few specific elements:
- A layer of clean gravel beneath the basement slab
- A heavy plastic vapor membrane over the gravel
- A continuous new construction radon pipe (PVC) starting in the gravel layer
- A vent path routing the pipe up through the house and out the roof
- No mechanical fan installed
The underlying concept relies on a natural thermal draft to draw soil gas out of the ground. Warm air inside the vent pipe rises naturally, pulling a small amount of trapped gas upward and releasing it safely above your roofline.
Our technicians appreciate when builders install these rough-ins correctly. The setup saves homeowners significant money if they ever need full mitigation.
Why Passive Systems Often Don’t Reach Below 4.0
The natural upward draft inside an unpowered pipe is incredibly weak. It depends entirely on ambient temperature differences, shifting winds, and atmospheric pressure. Some days the draft pulls a tiny bit of air, and other days it barely moves anything at all.
Our monitoring data shows this wintertime spike clearly. The stack effect pulls soil gas directly in through the foundation, and this force becomes especially strong during cold Midwestern winters. A simple, unpowered pipe simply cannot compete with the suction created by a heated building.
Recent state data confirms the severity of this issue. Approximately 71.6% of Iowa homes test above the Environmental Protection Agency action level of 4.0 pCi/L, with a staggering statewide average of 8.5 pCi/L. These numbers explain why a passive setup often fails to keep indoor air safe.
Bottom line
A passive system is a well-placed pipe waiting for a fan. Test first to find out if it needs one.
Passive vs. Active: Side by Side
If a basic pipe is not doing the job, upgrading the infrastructure is the standard solution. Choosing between a passive vs active radon system comes down to introducing mechanical suction. An active setup uses a continuous fan to overpower the house’s natural vacuum effect, which is exactly how a radon mitigation system works.
We always recommend comparing the two approaches directly. The differences in performance and upfront costs are substantial.
| Feature | Passive system | Active system |
|---|---|---|
| Fan | None | Inline radon fan running 24/7 |
| Suction under slab | Weak and variable | Steady and measurable |
| Typical results | Often modest reduction | Large reduction, typically below 1.0 pCi/L |
| Monitoring | Usually no gauge | U-tube manometer shows active suction |
| Typical 2026 Cost | Included in new build price | Roughly $900 to activate ($2,000+ for new install) |
| Electricity | None | Small, continuous fan power use |
| Best use | Built-in starting point | Proven long-term fix |
This upgrade is highly cost-effective compared to retrofitting an older home. While activating an existing pipe costs around $900, installing a brand-new system from scratch often exceeds $2,000. The savings are built right into your foundation.
Adding a Fan to Make It Active
The good news is that the messy, labor-intensive work happened during construction. The gravel layer, plastic membrane, and internal pipe are already in place. To turn a passive setup into an active one, a professional installer simply adds the missing mechanical components.
We follow a strict protocol for every activation job. This ensures the equipment performs optimally and meets all current safety codes.
- Check that the existing pipe is continuous, properly sealed, and routed through an attic or other unconditioned space outside the living area.
- Mount a premium inline radon fan, such as a Fantech or RadonAway model, on the pipe in the attic or another approved location.
- Run dedicated electrical power to the fan with an accessible disconnect switch.
- Install a U-tube manometer gauge on the pipe in the basement so homeowners can verify suction.
- Seal the sump pit lid and any obvious concrete foundation openings.
- Apply official system labels and explain the warranty.
Activation is usually much simpler than installing a brand-new system from scratch because the internal routing is already finished. Sometimes the existing pipe requires modifications. A builder might have routed the pipe at an angle that cannot securely hold a heavy fan, or the PVC joints might lack proper glue.
When choosing hardware, sticking to reputable brands pays off. An industrial-grade fan from Fantech or RadonAway carries a lifespan of 8 to 12 years when running continuously. Cheaper generic fans often burn out in less than five years, leaving your home unprotected.
Test First, Then Decide
Do not add a mechanical fan blindly or assume your air is toxic without proof. You must run a standard 48-hour short-term test before making any modifications. Testing gives you a concrete baseline number.
Our team advises every client to let the data drive their decision. The results dictate the exact next step you need to take.
- Below 2.0 pCi/L: Your passive setup may be doing enough right now. Retest every two years and after any major changes to the home’s structure or HVAC system.
- 2.0 to 3.9 pCi/L: Consider adding a fan. The World Health Organization recommends taking action at 2.7 pCi/L, and a fan offers a modest step for a meaningful drop.
- 4.0 pCi/L or higher: The EPA recommends mandatory mitigation. Activating the built-in pipe is the most direct path to safe air.
After activation, you must run a post-mitigation test to confirm the new, lower level. This follow-up ensures the installed fan is actually generating enough suction for your specific square footage.
Why New Homes Can Test High
People are often surprised when a brand-new, modern house produces a high reading. The reality comes down to modern construction techniques and regional geology. Today’s energy-efficient building standards actually trap soil gases inside.
A few primary reasons explain this common phenomenon:
- New properties are built extremely tight for energy efficiency, meaning any gas that enters has zero chance to dilute with fresh outside air.
- Settling concrete almost always develops micro-cracks in the first few years, creating fresh pathways for soil gas.
- The Des Moines Lobe glacial till beneath much of the state makes the soil highly permeable, allowing uranium decay gases to rise quickly.
- Every single county in Iowa sits in EPA Radon Zone 1, indicating the highest possible geological risk profile.
For builders, developers, and proactive homeowners, our guide on radon-resistant new construction covers exactly how passive rough-ins go in and when to plan for immediate activation. We update this resource regularly to reflect current building codes.
Staying informed helps you protect your investment.
How to Find Out If You Have a Passive System
Identifying your current setup takes just a few minutes. To confirm what type of infrastructure is in your home, look for these key indicators:
- A white PVC pipe, often labeled with a radon sticker, emerging from the basement concrete slab.
- A pipe connected directly to a sealed sump pump lid.
- A continuous vent pipe extending upward into the attic.
- An absence of any electrical fan spliced into the piping.
If you discover the pipe in the attic without a fan attached, you have a passive arrangement. This is exactly what the 2026 building codes require builders to leave behind.
Snap a few photos of the pipe in the basement and the open pipe in the attic, then send them to us along with your recent test result. We will review the routing to determine if an inline fan can be safely installed.
This quick virtual check provides a guaranteed flat-rate price without requiring a preliminary home visit.
Next Steps for Your Home
Discovering high gas levels in a beautiful new property feels frustrating, but the fix is entirely routine. You already own the most intrusive piece of the puzzle. The internal piping is ready for action.
We encourage every homeowner to order a short-term testing kit today.
A simple 48-hour check provides absolute clarity on your indoor air quality. If the numbers come back high, deciding between a passive vs active radon system is an easy choice. Upgrade the pipe, flip the switch, and breathe easier.