Mini Projects

How I got my Radon levels down with DIY mitigation

I’m not a certified radon mitigation professional. I’m not a professional contractor or licensed electrician. I’m also not a plumber. I want to make it very clear that the methods I used may not be in alignment with the EPA’s recommendations for radon mitigation. This post simply outlines the steps that I took personally to reduce the radon levels in my home.

That being said, I’d use this article more for inspiration, than as a step-by-step, how-to guide to radon mitigation.

You maybe asking yourself, “What does being an electrician or plumber have to do with mitigating radon?” You’ll soon find out that some of the steps require knowledge of basic wiring and drainage (in this case, draining air out of your home through PVC piping).

Measure your existing radon levels

You might already know you’re home radon levels. You may have purchased a mail-in home test kit or are going by your local average radon levels.

In either case, I encourage you to purchase your own radon detector, as you’ll want to measure levels in various areas of your home both before and after you install your mitigation system.

I personally chose the Safety Siren Pro Series3 Radon Gas Detector. I got it on Amazon for about $130. You simply plug it into a wall outlet and it will provide you a reading within 48 hours.

Before you decide where to install your mitigation system, you should spend a couple weeks testing your radon levels in various areas of your home.

During my testing, I found that my highest levels were coming from my sump pump crock. From what I have been reading, this is very common, as radon gas will take the easiest route to escape from the ground and into the air.

high radon reading

My radon reading: 39.1 pCi/L. Yikes!

With that in mind, the remainder of this article will be specific to installing a radon mitigation system over your sump crock.

You maybe asking yourself, “if the majority of radon is coming in through my sump pump crock, why not just cover and seal the crock?” The reason is that if you prevent the escape of Redon from one spot, it will simply trying to find another way to escape into your home.

Other common places where Radon tries to surface is through the expansion joint in your basement slab or even cracks in the basement floor.

Given this, the best course of action is to capture the radon gas as it enters and evacuate it, with a mitigation system, into the outside air.

So, let’s get started!

Finding the Right Sump Cover

If you have a sump basin (a plastic container that lines your sump hole), this process is a little easier. Sump basins typically come with a partial cover, but offer fully sealed covers as a separate purchase.

In my case, a separate sump cover was available, but it had a “not for radon use” warning imprinted on it. I purchased it anyway!

You may ask, why didn’t I go with the $100 radon safe sump cover offered by various manufacturers? The short answer is: because my cover cost $10 and it did the job after I applied a bead of silicone sealant around it.

If you don’t have a sump basin, don’t worry, it just takes a little extra work. I actually have a second sump hole that did not have a sump basin in it.

In this case, I purchased a 24 x 24 sheet of Lexan from my local Home Depot. I then used a jigsaw to cut a circular shape out of the Lexan that fit nicely over the sump hole. And again, once everything is in place you could be sealed with silicone to make it airtight.

The advantage to Lexan is that it’s clear and you are able to see if there is ever water in your sump hole.

Purchasing an Inline Exhaust Fan

The inline exhaust fan is what will actually draw the radon up from your sump hole and push it outdoors.

Since it will be running 24 hours a day, seven days a week, it’s important to consider these two criteria when purchasing your fan:

  1. Wattage vs. Airflow
  2. Sound

Don’t worry too much about the duct size, as long as it’s larger than 3 inches. You can reduce or expand to fit your piping as needed.

The fan that I purchased (the Fantech 100) had the following specs:

  1. 130 CFM
  2. 20 Watt
  3. Extremely quiet
  4. 4″ duct

The fan itself, at about $130, was over half the cost of the project. (EDIT: I see the fan is now about $110 on Amazon.)

The last thing to consider when purchasing a fan is wiring. I could not find a decent fan that plugged into a wall outlet. It’s possible I didn’t look hard enough, but all of the in-line fans I saw were hardwired.

Don’t let this scare you away, even if you don’t have the basic knowledge of wiring. Because we are installing this over a sump pump, it’s very likely that you have an outlet close by.

You can likely hardwire the exhaust fan to the wire that feeds your sump pump outlet.

Connecting the Fan

radon fan
This part was probably the easiest of the whole project. I simply purchased two rubber / flexible couplings and use them to join the fan with the rest of the system.

I did this in case the fan ever needs replacement. In the event that happens, I’ll just have to unscrew the rubber couplings and replace the fan.


Determine your exit point and fan location

Next, you’ll want to determine the exact point that the PVC piping will exit your home. I chose to drill a 3 1/2 inch hole in my rim joist (in the basement) and send the pipe out there.

You don’t want to drill that hole just yet, in case something goes wrong along the way. But, it’s important to identify where the exit pipe will be, so you can plan your piping.

You’ll also want to consider whether you want the exhaust fan to be inside or outside of the house. It is recommended that the fan be as far away from the radon source as possible so typically, professionals place the fan outside the house. The fan does a better job pulling the radon than pushing it out.

That being said, I personally chose to locate the fan inside my cozy basement, away from the elements (rain, snow, etc) and also improving outdoor aesthetics. I can’t be certain that I would not have achieved an even lower radon level if I placed the fan outside, but I’m still happy with the results.

Prepare your sump cover

sump cover

In this step, we’ll need to drill three holes into the sump cover, as listed below. All told, I believe this ran about $35.

  1. 3 5/8″ hole saw – for the 3″ radon mitigation pipe
  2. 1 5/8″ hole saw – for the 1 1/2″ sump water discharge pipe (if you have an old hole saw from a doorknob kit, that’s perfect)
  3. About a 1″ drill bit – for the sump pump wires (a wood boring bit will work fine)
  4. Hole saw arbor bit

Before you drill the holes, make sure you dry fit all the pipes together to ensure you locate the holes in the proper place on the cover.

Prepare your sump pump

We’ll need to do a couple things to our existing sump pump before we can apply the sump cover and seal it in place.

  1. The cut and splice.  I chose to make a cut in my sump pump power cord(s), run them through a small piece of conduit, then splice them together again inside a conduit box.
    My thinking is that this would make it a little easier to seal the hole where the sump power wires exit the cover.This was the only option with small conduit, as the actual plug at the end of wire doesn’t fit through 3/4″ conduit.So, why didn’t I just go with larger conduit? Since radon will also escape up into this conduit, I wanted to be able to seal around the wires, so a smaller size conduit made more sense.
  2. The pipe union. We’ll do kinda the same thing with the discharge pipe that comes out of the sump pump.  We’ll want to cut it and put a union in place to make it easier to service the pump if needed.

Seal the Cover

This is the easy part, but also the semi-permanent part. I used silicone to seal the cover over the sump hole. Anyone who has sealed with silicone before knows that it’s not permanent, but it’s a pain in the neck to remove the silicone bead that you created.

So the lesson here is to make sure that you have a high-quality some pump, that is positioned well in the hole, before you seal the cover on. Also ensure that all your electrical is in good working order before sealing the deal.

Once your electrical is done, pop the cover over the hole and pipes, then put a bead of silicone around the perimeter of the cover and also around the pipes that are coming out of the cover.

Outside piping

I choose to connect the PVC pipe coming out of the basement to a vinyl gutter than runs vertically along a piece of trim on the corner of my house. It is technically supposed to exit above the roof line, but I couldn’t justify the extra effort to do that.

I also know that the fan performance and rate with which the radon can be mitigated will be reduced by turning my exit pipe 45 degrees (as shown in the photo).  But, I felt it was more important to keep animals and water out of the system (especially the fan).

Try it out

Get a final radon reading before you seal the sump cover.

Then, after you seal the cover, turn on your in-line fan and put the system to work!

Reset your radon detector, then wait 48 hours and check your reading again.

If all goes well, you’ll see a drastic reduction in radon. Otherwise, check that all your silicone seals are complete and that all pipe joints are snug and glued properly.

I put a few images of the finished project on Imgur: http://imgur.com/gallery/VzwML