Radon Installation Process

What to expect when having your radon mitigation system designed and installed? Read on for information on the radon installation process.


Active and Passive Radon Systems

We will talk about active and passive sub-slab or sub-membrane depressurization systems.  An active system just means you will have a depressurization fan installed, either in the attic, garage, or on the outside of your home, while a passive system does not have a fan and relies on the natural drawl of air from the subgrade soil.  If a passive system is installed, be sure to plan the pipe route in a way that a fan can be added later if needed.  

Radon mitigation works by creating a vacuum suction, or depressurization underneath your home’s slab or crawl space thus collecting radon soil gas and venting it out to the atmosphere before the radon can seep into the home. 

With a slab, a mitigation pit drilled through the slab serves as the point of suction (sub-slab depressurization).  With a crawl space, perforated drain piping is looped throughout the crawl space and covered over top with a plastic membrane which serves as the point of suction (sub-membrane depressurization).  Whether a slab or crawl space, PVC piping is connected to the suction point and used as a pathway to vent the radon up and away from the home. 

Interior or Exterior Installation Systems

There are two types or general paths for a system, either exterior or interior.  Exterior systems place the fan on the outside of the home using a vent pipe along the side of the home to exhaust the radon gas above the roof line. 

Radon Installation Process

Interior systems route the pipe up into the attic, with the fan located either in the garage or attic, with the exhaust venting out the roof.

Radon Installation Process

From the mitigation pit, or crawl space piping, it is important that the PVC pipe route should be installed as close to a vertical run as possible, utilizing a minimal amount of elbows.  This will of course depend upon the buildout of the home, as some homes will require more elbows than others.  A pipe run as vertical as possible is even more important for passive systems than active. 

For interior systems, at times you can run the pipe in the utility chase where the water heater or furnace vent pipes are located.  This utility chase can provide a nice pathway up into the attic in such cases where there is enough space for an additional pipe.  Other interior routes for the radon piping include running through the backside of a closet, or along the garage wall up to the attic.


How Long is the Radon Installation Process?

Before installation, adequate time should be taken with a certified radon professional to find the right placement and path for the system.  Different slab levels, crawl spaces or additions to the home can impact where the suction point(s) needs to be as well as where the system can feasibly route. 

With a little planning you can ensure the system will address the current radon levels and be aesthetically pleasing inside and out. 

Concerning exterior systems, the system route and piping can be an eyesore for some homeowners.  Different kinds of vent piping such as color matched rain gutter downspout, copper, or painted PVC pipe can be utilized to blend the exterior system into the home making the system more aesthetically pleasing.  


Lower and Upper Levels of Radon Installation Process

We will now break down the high level activities in the installation process by talking about the ‘lower’ level and ‘upper’ level parts of the system.

The lower level installation process includes the following:

From the plan and/or design, verify the location of the mitigation pit where the pipe will go through the slab and drill a test hole to ensure you are not drilling into a structural footing. 

Drill out a 5 inch diameter hole in the slab to expose the subgrade aggregate. 

Remove about 10-14 gallons of aggregate (rock, gravel, dirt, clay, etc.) from under the slab to create a void, allowing the system to function properly.

Verify the pipe route either exiting the home for an exterior system or going up into the attic for an interior system.

The upper level installation process includes the following:

Verify the exit location out of the home (Exterior) or pipe path to go up into the attic (Interior).

Exterior – core drill a 5 inch hole in the foundation wall or cut a 5 inch hole on the side of the home for the pipe to exit.  Attach the fan and install the vent pipe up above the roof’s edge.  Draw power from an existing circuit to operate the fan using an off/on switch.

Interior – cut 5 inch hole(s) to route the pipe up into the attic.  Determine the exit location for the pipe to go through the roof.  Add a fan to the pipe in the attic and draw power to operate the fan.  Install a roof jack to support the pipe coming through the roof.


The lower and upper level activities connect together to complete the installation process.  Once the system is built, a manometer is placed on the pipe in a visible location that allows a visual to ensure the system is operating correctly.


After the Radon System is Built

Discharge/exhaust locations should in line with NRPP standards; 

Exterior system exhausts should be a minimum of 10ft. horizontally from any openable windows with adjoining or adjacent buildings, a minimum of 4ft. vertically from openable windows, and at least 6 in. above the roof’s edge. 

Interior system exhausts should be a minimum of 12 inches above the roof line and 10ft. horizontally from operable intakes (such as swamp coolers).


Avoid these fan locations:

  • cannot be place in living spaces in a home
  • cannot be in the crawl space or beneath the home
  • cannot be in the garage if there is a living space above the garage
  • cannot be placed in an occupied attic


Allowable fan locations:

  • in the attic
  • in the garage (no livable space above garage)
  • outside the home


For passive systems, it is important that the PVC pipe is run through the buildings in the interior walls – if the pipe is run outside the home or in the exterior wall, it will reduce the natural thermal stack as the system tries to vent the gas, thus reducing its effectiveness.


If you need professional Radon Mitigation Installed, please contact us to start your radon installation process and get it resolved as soon as possible.