A passive radon mitigation system is a system without a fan. This type of system may have been installed when your home was being built. It typically includes:

• 4 inches of rock under the concrete floor
• Drain tile pipe
• Six-mil poly between rock and concrete slab
• Vent pipe running from beneath concrete slab and exhausting 1 foot above your roof
• Outlet next to vent pipe in attic

To check if your home has a passive radon mitigation system, take a look in your basement. In the mechanical room, storage room, or under the stairs, you should see a 3-inch white or black plastic pipe that comes up through the concrete floor or sump basket cover, goes up to the ceiling, and disappears inside an interior wall of your home. The pipe should have a label that says, “This is a component of a radon mitigation system, do not tamper with or disconnect.” Or, the installer may have simply written “radon” on the pipe.

In Minnesota, if the building permit for your home was obtained after June 1, 2009, it should have a passive radon mitigation system.

Just because your home has a passive radon reduction system, it doesn’t necessarily mean your family is safe. Studies have shown that most passive systems only reduce radon levels by about 50 percent. When high winds blow over the top of the vent pipe on your roof, radon levels can actually increase.

Often, the plumber that installed the system was not trained or certified to do radon mitigation. There is no national standard for radon-resistant new construction for builders to follow. Consequently, many systems are installed incorrectly.

Some of the common mistakes we find are:

• Vent pipes filled with concrete
• Vent pipes coming out of the sump basket
• Cracks and gaps in the concrete floor that are unsealed or have opened up as the concrete continued to shrink
• Unsealed bath/shower drains that are open to soil
• Unsealed plumbing penetrations
• Unsealed sump covers
• Untreated areas of the home, such as crawl spaces
• No room in the attic to add a radon fan

It’s possible to convert a passive radon system into an active one. We add a radon fan to create suction under your home. This is done by cutting out part of the vent pipe in the attic and adding a radon fan.

If your home was built before June 2009, you’ll likely need a drain tile depressurization (DTD) or sub slab depressurization (SSD) radon reduction system. This is also referred to as active soil depressurization or ASD. Both are active radon mitigation systems. They create a vacuum under your home that gives the radon an escape route.

Drain tile depressurization utilizes existing drain tile (perforated pipe) below the concrete floor of your home to create an easy path to pull the radon gas into the mitigation system. A sub-slab depressurization system works by creating suction in a void created below the floor to draw the radon-laden soil gas into the radon system.

DTD systems are typically very effective at reducing radon concentrations and often the easiest and least expensive systems to install. One drawback to a home with drain tile is we often have to seal many air leaks. These leaks are usually found where the concrete floor meets the foundation wall and at the tops of concrete block walls. If the basement is finished it makes it hard to seal air leaks. A radon fan that can move a lot of air may be needed. These high-flow systems come at a price, including the extra cost to run a bigger radon fan and the loss of conditioned air (air you are paying to heat and cool) that is drawn into the radon system and exhausted outside.

Here’s a look at American Radon Mitigation’s DTD installation process:

1. We start by sealing cracks and openings in the floor. If you have block walls, we’ll seal any openings in the top of the block. If your sump basket cover can’t be sealed, we’ll install one that can be. Sealing makes a radon system more efficient and effective.
2. Next, we’ll figure out the best spot to put the suction point based on your preference and the route out of your home.
3. We then core a 5-inch hole through the concrete floor, being careful to collect all of the dust to keep your home clean.
4. Once the hole is created, we remove 5 to 20 gallons of material to create a collection point.
5. Next comes more diagnostic testing to determine if additional suction points are needed, if the drain tile should be tied into, how much air we need to move, what size pipe to build the system out of, and which radon fan will be best for your home.
6. Then we install the vent pipe that is either routed out the side of your home, into the garage, or up through a closet and into the attic.
7. We then do more diagnostic testing to be sure the fan we select is going to operate efficiently and within its operating range.
8. Then the vent pipe continues from the radon fan and out through the roof.

If your home doesn’t have a drain tile system, then we’ll install an SSD system. The function of an SSD system is similar to that of a DTD system. However, instead of running collection points through a drain tile system, we drill directly into your home’s concrete floor.

SSD systems often require more  suction points than DTD ones do. Our extensive diagnostic process will help us determine the number of suction points required to create a vacuum under your home. Most SSD systems also require a high-suction fan to effectively and efficiently remove radon from your home. Since they’re more complicated to test and design, SSD systems are often more expensive than DTD ones.

With any active radon mitigation system, the key to getting your levels low is creating a vacuum under your entire home. The only way to know if we’re achieving this is to take the time to do the diagnostic testing. In other words, if we create a suction point in the mechanical room in the basement, is the vacuum under the home reaching the bedroom on the other side of the basement where your kids sleep?

Knowing Your Active Radon Mitigation System Is Working

We install a U-tube manometer that measures the suction of a fan. If the fluid levels in the U-tube are different, the radon fan is on. If the fluid levels are equal at zero, the fan is not working. You should call for service. In addition to the manometer, we offer a low airflow alarm that starts to beep within 30 seconds if the airflow in the pipe drops, indicating a problem.

We also provide you with a post-mitigation radon test kit to ensure the radon levels have dropped. This test can be started 24 hours after the system has been turned on.

If you sign up for one of our service plans, we send you out a long-term test kit every year to ensure your radon levels stay low.

With any active radon mitigation system, the key to reducing radon levels as low as possible is to create a vacuum under your entire home. The only way to know if we’re achieving this is to take the time to do the diagnostic testing.

In other words, if we create a suction point in the mechanical room in the basement, we need to confirm that the vacuum reaches the bedroom on the other side of the basement, where your kid sleeps. If it doesn’t, the radon in your home is not completed mitigated. Our diagnostic testing process ensures everyone in your family is protect from radon, regardless of where they are in your home.

We don’t take a one-size-fits-all approach to selecting your home’s radon fan. Our diagnostic testing process ensures we are creating vacuum under your entire home and installing a fan that’s not undersized or oversized. An undersized fan may not lower your radon levels adequately, and an oversized fan costs more to run.

Code requires us to install your radon fan in an unconditioned space. An unconditioned space is one you don’t heat or cool. Often, this is an attic space or exterior of your home.

Often, we take a phased approach to mitigating crawl spaces. Treating the crawl space is expensive and not always required.

First, we’ll design and install your home’s mitigation system to treat the basement. Then, we’ll retest the radon levels in the basement and the room above the crawl space. If they are both low, then no further action is needed.

But if the level above the crawl space is high, we’ll recommend mitigation. If left unaddressed, the radon from the crawl space will rise up into the living spaces above it, putting your family at risk.