One of the most common methods for avoiding potential flooding issues is installing drain tiles alongside the foundation during construction. While this porous-pipe network is excellent for minimizing water damage in your basement, it has a second benefit that many homeowners are completely unaware of.
Installing a new radon mitigation system in a home with drain tile is more effective and easier to accomplish. In fact, with the right knowledge, tools, and construction, one could even complete the task themselves.
Whether you’re a DIYer trying to save some money or a fellow radon mitigation specialist looking to improve your process, this step-by-step guide will show you everything you need to know to install a radon mitigation system in a home with drain tile.
If you have any questions or wish to leave this job to the experts, contact American Radon Mitigation today.
Please note: We also include links to many of the products we use. As an Amazon Associate, American Radon Mitigation earns a small portion from qualifying purchases.
Install a sealed sump basket cover
The first thing to do is head down to your basement and remove the cover from your sump basket. You might need to replace this if there is too large an opening to get a proper seal.
Trace the outline of your cover onto a sheet of clear ¼-inch LEXAN, which you can order online. Now cut out the circle using your preferred saw. If you don’t want to make your own, you can find aftermarket sump domes that will work just as well.
Now cut out a 4-inch hole in the cover for an access port. Put the new cover in place and screw it down with 4 Tapcon concrete screws. Once it’s secured, apply silicon around the perimeter to give it a thorough seal.
Add diagnostic test holes
For the next step, you’ll need a rotary hammer to drill several test holes into the concrete floor using a ½-inch drill bit. These test holes will allow you to test the strength and extent of the suction that your radon mitigation system will create.
Once they’re drilled, you’ll need to insert a small rubber hose with a rubber stopper at the end. These will come packaged with most micro-manometers but can also be purchased separately in a kit.
Once those are in place, go back to your micro-manometer so you can measure the pressure.
Conduct a communication test
First, take the hose of your shop vac and insert it into the 4-inch hole in the new sump cover to measure your pressure. Seal your vacuum hose in the sump basket and then turn on the shop vac. Be sure the vent your shop vacuum outside so that you don’t fill your house with radon.
Now take a look at your micro-manometer(s). You should notice the numbers go from positive to negative. This indicates that the house is not drawing in radon, which is good.
Identify any air leaks at the top of the concrete block wall
If you have an unfinished basement, it’ll be much easier to create a more effective and efficient radon mitigation system. This is because the drain tile ties into the concrete block wall, which typically has openings at the top. When you turn on the radon system (or a shop vac for this test), it’s going to pull the conditioned air (smoke) out of the house.
Light the wick of a smoke pen and place it on top of the block wall, hanging over the edge of one of the openings. With the shop vac off, the smoke should steadily rise up. When you turn it on, the smoke should get drawn down into the opening.
Foam the top of the concrete block wall
If you take the time to seal the top of the block wall properly, you can create a much more effective and efficient radon mitigation system. Take some small pieces of fiberglass insulation and use them to fill in any large gaps and openings. The insulation will prevent the spray foam from falling into the block wall.
Please note: Always have proper ventilation because spray foam vapors are flammable and can be ignited by pilot lights.
Seal cracks in the concrete floor with radon sealant
Since the key to proper radon mitigation is creating a vacuum under your entire home, it’s crucial that you seal up any cracks or openings in the concrete floor. These are typically found near load-bearing walls, walk-out walls, and any plumbing block-outs.
We recommend using an environmentally safe, VOC-compliant radon sealant. Unlike polyurethane sealants, it’s much better for you and your family to breathe in.
Make sure to brush and vacuum the areas before sealing for maximum effectiveness. Apply one coat along each crack and gap, and then run your finger or a putty knife back over to push it down into place.
Once you’re done sealing, you’ll want to do another communication test, so head back to your shop vac and flip it on. You should notice the numbers on your micro-manometers are significantly more negative than before.
While this isn’t required to make your radon mitigation system work, it will make it a lot more effective and efficient because it won’t be drawing as much conditioned air out of the house. It will also help reduce any potential backdraft situations you may face.
Create the suction point
The next step is to drill a large hole in the concrete floor using your rotary hammer and a 5-inch diameter core bit. While optional, we recommend using a dust collection device (like the one seen below) to help keep excess concrete dust out of your home.
Once the hole is cut, remove any concrete chunks with your hand and vacuum out additional debris. Using a 4-inch hole saw, cut into the top of the drain tile to allow for greater airflow.
Now cover the hole with a dust collection hood and secure it to the floor with duct tape.
Use a pitot tube to measure airflow
Now that your suction point is complete, it’s time to take a Cubic Feet per Minute (CFM) reading to give us our desired pressure field extension. To do this, attach a pitot tube to the suction point you just created. On the other end, connect the hose of your shop vac.
A pitot tube like this will allow you to measure how much air is moving through the system. Like we mentioned previously, the key to getting your radon levels low is to create a vacuum (suction) under your home. The only way to know if we’re achieving that is to measure.
Using the three test holes that you connected earlier, keep an eye on the levels as you run the system. The goal is to hit 5 pascals (Pa) of negative pressure in your farthest, weakest test hole.
In this system, we were moving 80 cubic feet of air per minute. That tells us that a 3- inch pipe would be restrictive for proper airflow, so a 4-inch pipe would be required to make sure we can move enough air through the system.
Run the vent pipe from the basement to the garage
The next step is to create the vent pipe system to move the air from the basement to the garage. To do this, head out to your garage and locate a shared wall to the basement. Using your 5-inch hole saw, drill a hole large enough for the 4-inch pipe to fit through.
Head back down to the basement because you’re going to need to install the rest of the piping system to connect from the suction hole to this point.
Using a small brush, thoroughly coat the outside end of a 6-inch piece of pipe with a low VOC, clear PVC cement. Then do the same to the interior end of your PVC coupler and repeat.
Attach the two pieces, and then wipe away any excess glue with a towel. Then add radon sealant around the outside edge, as well as the perimeter of the suction hole.
Now place the pipe into the suction point, ensuring there is a good seal all around it. Then apply more PVC cement to the pipe and the coupler.
When you glue these two pieces together, make sure you give the pipe a quarter turn, as the glue will set better that way.
Now apply the same technique to the top of the pipe and one end of a 90-degree elbow piece. This final piece should fit nicely through the hole you created earlier into your garage.
Once everything is together, screw two metal two-hole straps around the pipe’s top and bottom and into the wooden frame to securely fasten it to the wall.
Install a U-tube manometer and radon system alarm
Now it’s time to install the more visual aspects of the radon mitigation system. At around eye- level, use a single screw to attach an easy read manometer. A U-tube is essentially a visual gauge that will tell you if your radon mitigation system is working or not.
Now drill a 1-inch hole into the pipe roughly 4-5 inches above the manometer’s top. This hole is where you will install the radon airflow alarm.
This battery-powered monitor will warn you if there is little or no airflow through the pipe. Now secure the radon alarm and check that it’s level.
Install a smoke sealant and firestop collar
The next step is to head back out to the garage, where your pipe is stubbed out. Since this interior garage wall is fire-rated, you need to ensure that you maintain its integrity to adhere to local fire codes.
The first thing you need to do is apply a layer of smoke sealant into the gap around the pipe.
Next, you’re going to need to install a 4-inch firestop pipe collar over the top. In the event of a fire in your garage, the PVC pipe will melt away, but the intumescent material in the collar will expand and seal up the hole, keeping smoke and flames out of your home.
Secure it to the wall with #8 wood screws and 1-inch washers. If there is no wood where you need to fasten it, you’ll have to use toggle bolts so that it doesn’t pull out of the wall in the event of a fire.
Install the insulated vent pipe in the garage
Now you need to install the garage portion of the vent pipe. Begin by taking your PVC elbow connector and measure it so that it’s 5 inches off the wall. Then mark that on your stubbed-out piece, so you know where to cut.
Using a reciprocating saw, cut the PVC pipe at the mark you just made.
Now you’re going to need to make two wooden pipe supports out of a 2×4-inch board. Since the vent pipe will be 5 inches from the wall, these will help to secure it in place firmly.
Start by cutting four 18-inch pieces using a wood blade on your reciprocating saw. A table or circular saw will work just fine for this step if you have them on hand.
Now screw two of the pieces together lengthwise so they make an “L” shape.
Now that you have your two supports assembled, it’s time to attach them to the garage wall. Use a stud finder to make sure these are going directly into wood.
Attach the first one 3 feet above where the pipe comes into the garage and the other roughly 3 feet below the garage ceiling (or rafters). Now measure and cut the length of pipe you’ll need to reach the ceiling.
Take this piece and attach it to the elbow connector, using the same gluing techniques we discussed earlier. Now grab the entire piece and slide it into flexible duct jacketed insulation.
There are four main reasons for adding this layer of insulation to your pipes:
- It stops mold and mildew from forming on the pipe.
- It will help keep your pipes from freezing in the winter.
- It will help to soundproof your system.
- It stops condensation from forming on the pipe and dripping on your drywall and attic insulation.
The next step is to attach this section of pipe to the wall. Once again, thoroughly cement the end of the pipe and fitting and give it a quarter turn to help set the glue.
Using two more metal two-hole straps, secure the pipe to your two wooden supports that extend out from the wall. The garage portion of your radon mitigation vent pipe is now nearly complete.
Run the vent pipe up into the garage attic
Now the next step is to run the vent pipe up into your garage attic. First, use a marker to trace around the top of the pipe so you know exactly where to cut into the ceiling.
You probably noticed the additional bend in the pipe pictured above. That was necessary because the house cantilevered out over the garage by two feet in this particular case, so we had to extend the pipe to compensate for that.
Chances are, this will not be the case for you, so your pipe can run straight up.
Now drill a pilot hole in the center of the circle you just drew. This will mark where you will need to cut your hole down from the attic. Head up into the attic and, again, use your 5-inch hole saw to drill down into the garage.
Now cover the next piece of PVC pipe with insulation and attach it to the top of the garage section to protrude up through the ceiling.
The final step is to install the second firestop pipe collar into the ceiling. Since this one will not fasten to wood, be sure to use toggle bolts for extra hold and 1-inch fender washers. Once that’s secured in place, spread out your insulation so the entire length of the vent pipe is covered.
Run your vent pipe through the attic
Now you’ll need to head back up into the attic to complete the final section of the vent pipe. The first thing you’ll need to do is apply your smoke sealant around the stubbed pipe to complete the firestop assembly.
From there, you’ll need to run the length of the pipe across the attic until it’s directly beneath the exterior exhaust point. Next, measure the length of PVC pipe you’ll need, cut it, and cover it with insulation.
Now attach another elbow connector, following the same gluing techniques from before. You can then glue and attach that piece to the stubbed-out pipe.
You may need to add a 2×4 for support. Then use another two-hole strap to secure the pipe.
Now measure and cut a length of PVC pipe that will run vertically up to about two feet from the roof’s exhaust point.
Cement and attach a 90-degree fitting to the bottom of this piece and cover with more insulation. Now glue and attach this section to the horizontal piece running across the attic. Use a bubble level to ensure this piece is as vertical as possible.
Cut a hole through the roof
We’re finally ready to cut a hole through the roof for the exhaust point of your system. To do that, you’re once again going to need the 5-inch hole saw.
Drill up through the roof to the depth of your hole saw. From here, go up to the roof and finish the hole from above.
Now that you’re through the roof, it’s time to attach the radon fan and complete your radon mitigation system setup.
Select and install your radon fan
Now you’re ready to choose the ideal radon fan for your home. When it comes to radon fans, there are three main categories:
- Low suction, moderate airflow
- Medium suction, moderate to high airflow
- High suction, low airflow
Knowing how to choose the right radon fan is essential because it’s a significant factor in how effective your radon mitigation system is at reducing your family’s risk of lung cancer.
When it comes to fan selection, bigger isn’t always better, as an oversized fan will unnecessarily spike your utility bill each month. It will also pull out more conditioned air from your home, which will mean more heating and cooling costs.
Complete the rooftop installation
The next step is to head back up to the roof and drop the final section of pipe down through the exhaust point hole.
Now place a roof flashing over the top of the pipe. The self-sealing collar should slide right over the pipe and doesn’t require any caulking around the pipe collar.
Using a piece of chalk, mark where to cut back the shingles so you can slide in the base of the flashing.
Now slip the top portion of the flashing underneath the shingles, so it’s securely in place. Again, use a bubble level to ensure the exhaust pipe is vertical.
Now pull the pipe slightly up, so the collar is popped into place. Use a rag to clean the pipe.
Now head back into the garage attic and cover the inside portion of that pipe with more insulation. Then attach it to the top of your radon fan using another flexible coupler. Make sure your radon fan is perfectly level so that it operates as efficiently and effectively as possible.
Tighten both couplers and spread out the insulation to completely cover the piping. To wrap up your attic installation, you’ll need to have a licensed electrician come out and install a light and an outlet within six feet of your radon fan.
Make sure you have a 6-foot power cord to power the radon fan from this outlet.
Now head back up to the roof one last time to complete the installation. You’re going to want to install a 4-inch fan pipe cap with a screen to keep squirrels and birds—as well as acorns, leaves, and other debris—out of your exhaust pipe.
While this last step is optional, we recommend spray painting the pipe to match your shingles. This paint will make it far less noticeable to anyone looking up at the roof.
Check water heater for back drafting
One of the last things that we do—and we find this step very important—is to check your natural draft water heater for back drafting. If you do not have one of these, you can go ahead and skip to the next section.
How to check for proper water heater draft
- Turn down the heat at the furnace or boiler if there is a shared vent.
- Close all windows, doors, and fireplace dampers (if applicable).
- Turn on everything that exhausts air out of the house. This can include:
- Bathroom exhaust fans
- Clothes dryer
- Kitchen exhaust fan
- Turn on your radon fan.
- Run hot water long enough to get your water heater to turn
- Light your smoke pen and place it underneath the
You want to make sure that the smoke is drawn up into the flue. Building Performance Institute (BPI) standards allow up to one minute of back drafting. If the smoke spills out for more than a minute, it means the house is drawing air down the flue and needs more make-up air.
When your water heater turns on, the exhaust gases will have nowhere to go but back into your basement, which is a significant carbon monoxide concern. Unfortunately, this is a widespread issue that we see all the time.
If this is the case in your home, you’re going to want to have an HVAC or plumber come to correct the issue before you start running your radon mitigation system.
Radon system wrap-up
Once you’ve got everything cleaned up and put away, there are a few final things to check before calling it a day. Now that you have pressure field extension (suction) under the entirety of your home, you’ll want to complete the following radon system checklist:
- Is your farthest, weakest test hole reading over -5 Pa on the micro-manometer?
- Is your U-tube manometer displaying fluid at different levels?
- Have you completed your post-mitigation radon test at least 24-hours after the system has been running?
If you’ve done all that and your radon levels come back low (ideally one pCi/L or less), then your home is in good shape, and your family can breathe easily.
Visit the American Radon Mitigation website to learn more and get a free radon mitigation estimate for your home.