Radon Mitigation

**Jim Robinson** · 02-28-2011, 07:03 PM

Is it customary to have a rain cap on top of the radon vent line?
Believe it or not, this is the first time I've seen any type of radon mitigation system in my area in eight years of inspection.

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**John Arnold** · 02-28-2011, 07:46 PM

Around here they generally have an elbow at the top.

Hector Acevedo · 02-28-2011, 07:48 PM

I'm not sure if a vent cap is needed or not. Try looking in the IRC appendix F. Look at section AF103.5.3 Vent Pipe. Vent pipe must terminate 12" above the roof. Termination point must be at least 10' from any building opening. Don't know if that helps. Don't see any requirement for a cap.

**Scott Patterson** · 03-01-2011, 06:04 AM

Originally Posted by Jim Robinson

Is it customary to have a rain cap on top of the radon vent line?
Believe it or not, this is the first time I've seen any type of radon mitigation system in my area in eight years of inspection.

Nope, it is not needed. Any water that gets into the pipe will drain out in the pit that the pipe is sitting in.

**Jack Feldmann** · 03-01-2011, 06:42 AM

ditto what Scott said.

Eric Williams · 03-01-2011, 06:58 AM

No use of elbows around here.
Note: This install may be newer. Often times the inside of the pvc pipe is full of mold.

**Darren Miller** · 03-01-2011, 07:51 AM

Originally Posted by Scott Patterson

Any water that gets into the pipe will drain out in the pit that the pipe is sitting in.

If the system is operational, how does the water get past the fan?

**Jim Robinson** · 03-01-2011, 07:56 AM

That's what I was wondering as well. Maybe the fan is waterproof or the motor is enclosed? The diagrams I found online did not have a rain cap as part of it. I don't see what it would hurt to have one, though.

**Darren Miller** · 03-01-2011, 11:17 AM

I have a system in my house. There is no cap or elbow installed.
Every year for several weeks I turn the fan off and run my monitor just to see what the level is without the fan running.

When I turn the fan back on, I can hear the fan/air pushing the rainwater back out (there is a horizontal section of pipe where the water lays).
From this, I can assume the air flow keeps the water out of the pipe when the fan is operational.

**Scott Patterson** · 03-01-2011, 11:27 AM

The most common fan used is by Fantech and they have drains built into the fan housing so that water can drain if it get trapped. Most of water that is in a radon system is from condensation and not rainwater. the fan is pulling up cool air from under the foundation and then pushing it up into the warm pipe and we have condensation!