Design Basics
Radon Mitigation AKA Radon Reduction
Mitigation systems establish a slight vacuum beneath the foundation to draw soil gases away from interior spaces and vent them safely outdoors.
EPA studies show, when a radon reduction system is installed carefully, concentrations are typically reduced by 80-99%
Basic Requirements:
To comply with NRPP safety standards, all radon discharge pipes are required to terminate above the roofline, directing the gas away from occupied areas.
The fan must be located outside or above occupied spaces.
Cosmetic Options
Exterior or Interior Design?
The cosmetic options available are dictated by the home's design.
We will work with you to determine available piping routes and provide you with options that take aesthetics into consideration, such as visibility from the street or locating pipes in unfinished areas.
Suction Pipes and Suction Points
Suction points are typically through the concrete slab to a suction pit. If suction under the entire slab is not possible from a single point, additional suction points or jumpers may be used. Dirt crawlspaces would need the soil covered and sealed off (encapsulating). A suction point under the barrier, consisting of a perforated pipe, is typical. Some systems with multiple foundation types and mid-slab footings require multiple suction points, balanced to provide proper suction (pressure field extension).
Effective Design
Every home is unique, and its specific structure—whether it has a basement, a crawl space, or a concrete slab—determines how the pipes and fan system must be set up.
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The Fan's "Pull" (Vacuum Strength): The type of suction needed depends on what is directly under your house. For example, thick clay or tightly packed dirt requires a more powerful vacuum to pull the gas out than loose gravel would.
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The Amount of Air Moved (Air Volume): The system must move enough air to account for any empty spaces or "leaks" in the soil and foundation. If the soil is very porous or if there are gaps where air can escape, the system needs to pull more air to keep the radon moving out. Sealing of cracks and openings to the interior is utilized to improve system function, effectiveness, and efficiency.
Radon doesn't just come from one spot; it seeps in through any part of your home that touches the ground.
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Total Coverage: To get the best results, every area in contact with the earth—including the garage—should be treated.
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Size Matters: The larger the area of the home touching the soil, the more entry points there are for radon to enter, making total coverage essential for safety.
Fans and Electrical
When a radon system is installed correctly, it provides long-term protection with minimal maintenance. Here is a breakdown of how these systems work in simple terms:
The Fan: Low Power, High Reliability
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Constant Protection: Once installed, the system keeps radon levels low for as long as the fan is running.
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Energy Use: The fan runs 24/7 but uses very little electricity—about the same as a standard 40-80 watt light bulb. It actually moves less air than most bathroom exhaust fans.
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Weatherproofing: Radon fans are built to handle the elements. Rain and condensation flow straight through the fan and drain into the soil below. Because of this, "rain caps" are not used on the exit pipes; in fact, they can trap moisture and cause the system to freeze shut. Interior pipe routing and fans in attics or garages help function and reduce freezing potential.
Choosing the Right Size
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The Right Fit: Bigger is not always better. A fan that is too large can be noisy, waste energy, and even interfere with other appliances like your water heater or furnace. A fan that is too small won't keep you safe when the weather turns cold.
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Soil Type: If your home is built on tight soil or sand (common in older homes), you may need a "high suction" fan. These are powerful and can vibrate more, so choosing a smart location for the fan is key to keeping the house quiet.
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Sealing is Key: If your home is well-sealed against the soil, a smaller, quieter "light duty" fan can often do the job effectively.
Managing Moisture and Noise
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Condensation: Even if it isn't raining, the system creates about a half-gallon of water every day just from condensation (especially in winter). The piping must be angled so this water drains back into the ground rather than pooling in the pipe.
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Ice and Humidity: The air blowing out of the pipe is extremely humid. It should never be pointed at your siding or roof, as the constant moisture can cause wood to rot or ice to build up and block the pipe.
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Quiet Operation: Most noise issues aren't caused by the fan itself, but by the pipes vibrating against the wood framing of the house. Proper installation ensures the pipes are braced to stay silent.
When installing a radon system, the electrical work must be safe and follow modern safety standards. Here is a simple guide to how the system should be powered:
Electrical Safety Standards
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Code Compliance: New wiring must meet current electrical safety codes and should never make your home’s existing electrical system less safe than it was before.
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The Power Source: The fan can usually be plugged into or wired to almost any existing circuit in your home.
Proper Set-Up by Location
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In the Attic: The fan should plug into a standard outlet located within 6 feet. This allows a technician to easily unplug it (disconnect it) to perform maintenance. There should not be a wall switch that could accidentally be turned off.
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Outside the Home: The wiring between the fan and the power box must be protected by a sturdy, weather-proof pipe (conduit). There must also be a weather-proof "on/off" switch mounted right next to the fan so it can be turned off safely during repairs.
Common Mistakes to Avoid
For your safety, the following setups should be avoided:
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Shared Switches: The fan should never be on a circuit controlled by a light switch (if someone flips the light off, your radon protection stops).
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Exposed Wires: Using extension cords or running wires through walls is unsafe. All exterior wiring must be protected by a hard conduit.
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No "Serviceman Switch": For safety, a person working on the fan must be able to see the plug or the power switch. If the disconnect is in another room or out of sight, it is a safety hazard.
Sealing and Sumps
To make a radon mitigation system work effectively, you need to create a barrier between the ground and your living space. Here is an explanation of why sealing is important, and how it's done:
Why Sealing Matters
The goal is to create a small amount of suction (vacuum) beneath your home to draw radon gas away.
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You Can't Seal Everything: Even the most meticulous sealing efforts will miss tiny, invisible gaps where air can leak.
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The System Still Works: The radon system is still effective because it constantly pulls the gas away from the house, preventing it from entering your air.
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Focus on the Big Leaks: Sealing large, accessible openings is a crucial part of the process.
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Energy Use: The system pulls a small amount of heated or cooled air out of your home, which costs a little money in energy. However, spending a lot of money to find and seal every tiny "hairline" crack is usually not worth the cost.
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The Right Fan Helps: Using the correct size fan helps minimize energy loss. In homes with very small, well-sealed slabs, a tiny fan can be used to maximize energy efficiency.
Sealing Materials
Here are the typical materials used to seal key entry points:
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Sump Covers: These are custom-made from a clear, durable plastic so you can still see inside the pit. They must be anchored securely, sealed airtight, labeled, and strong enough to support the weight of an adult. They should also have an access port for maintenance.
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Floor-Wall Joints: Urethane caulking is used for these areas.
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Large Cracks & Openings: Caulk, expanding foam, or mortar are used depending on the situation.
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Drains that Go to Soil: Special "air traps" with floats are used to let water in but prevent radon and air from coming up.
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Open Dirt Floors: A heavy-duty plastic (poly) sheeting is placed over the open ground and sealed to the walls.
Important Note: Sealing Alone is Not Enough
The Environmental Protection Agency (EPA) warns against relying solely on sealing to reduce radon. While sealing alone might sometimes reduce levels slightly (10-50%), the results are unpredictable and often have very little effect. A proper mitigation system with a fan is required for consistent, safe results.
System Maintenance
A radon system is designed to work for many years, but it does require occasional "pulse checks" from the homeowner to ensure it is doing its job.
1. How to Check Your System
Because radon fans are nearly silent, you can’t always tell they are working just by listening. That is why every system includes a pressure gauge (a U-shaped tube with colored liquid) attached to the pipe.
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Check it Regularly: You should look at this gauge every so often. If the liquid levels on the two sides are uneven, the fan is pulling suction and the system is on.
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What the Gauge Tells You: Think of this as an On/Off indicator. It tells you the fan is running, but it does not measure the actual radon levels in your air.
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What to do if the Fan Fails: Don't panic. Radon is a long-term health risk, so a few days without the fan is not an emergency. However, you should arrange for a repair soon.
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Troubleshooting: If the gauge shows the fan is off (the liquid levels are equal on both sides):
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Check your electrical panel for tripped breakers or check if a nearby wall switch was turned off.
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Check the small clear tube tucked into the top of the gauge to make sure it hasn't come loose or gotten clogged.
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If it still isn't working, call a professional for service.
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2. Testing for Radon
The only way to know for sure that the radon levels are low is to test the air.
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The Initial Test: Immediately after the system is installed, a "continuous monitor" test should be done. This provides hourly readings to ensure the system was designed correctly for your home.
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Routine Follow-ups: Even with a working fan, the EPA recommends testing your home every two years. This ensures that changes in the soil or the home's structure haven't affected the system's performance. A consumer grade continuous monitor such as Ecosense EcoBlu, or EcoQube are recommended.
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How to Test: You can hire a professional for a certified test or buy an inexpensive DIY home test kit at most hardware stores. Both methods are effective for routine check-ups.
Understanding Radon Entry
While simple soil is the most common source, radon can also originate from crushed stone aggregate, natural rock formations, or other permeable materials beneath your foundation that allow the gas to move easily.
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The Source: Radon gas is naturally produced by the decay of uranium in the soil beneath your home.
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The Vacuum Effect: As warm air rises and escapes through upper floors (often called the "stack effect"), it creates a slight vacuum. This negative pressure pulls radon gas from the soil into your home.
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Entry Points: The gas enters through common pathways such as foundation cracks, construction joints, floor drains, and gaps around utility pipes or sump pumps.
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Circulation: Once inside, your heating and cooling systems further distribute the gas, where it can reach unsafe levels.
The most effective way to address this is through a radon mitigation system, which uses a fan and vent pipe to pull the gas from beneath the foundation and release it safely outdoors.