Sealing a Radon Entry Pathway - American Radon Mitigation

Sealing a Radon Entry Pathway

My sister, Calley, recently bought a home in New Brighton, MN. She had a radon test done during the home inspection. The radon was 2.5 pCi/L. 

After she moved in, I was looking at how we were going to install the radon mitigation system. I happened to look behind the furnace and noticed that it didn’t look like there was concrete underneath it. I ended up removing the return duct from the side of the furnace and was able to see a hole open to the soil. 

Return duct was removed from furnace.
The void was visible when the return duct was removed.

This opening to the soil is an easy pathway for radon to enter the home. Radon entry can be increased when the furnace fan is operating as it could create suction on the soil that draws more radon into your home.

A closer look at the opening to the soil below the furnace.
A closer look at the opening to the soil under the furnace.
Radon Entry Pathway
And an even closer look.

This opening under the furnace is fairly common in older homes that were built in the winter months. The concrete floor can’t be poured if there is frost in the soil so builders will heat the home during construction to allow for the floor to be poured.


Now To Seal the Opening

Next, we used a garden hose to rinse the dirt off the concrete and a shop vac to suck up the water. This gave us a clean surface for the new concrete to stick to. 

Then we mixed up half a bag of premixed concrete and filled in the void.

Concrete was used to fill in the cavity under the furnace.
Void filled with concrete.

The last step was to connect the return duct and turn the furnace back on. 

Final Thoughts

When doing radon mitigation, we want any openings from your home to the soil sealed as much as possible. This allows for a more effective and efficient radon mitigation system to be installed in your home.