Radon Mitigation

[WoodChuckDad]

As part of my new home build, I am installing a radon mitigation system. The information I have been reading suggests that I only need a single vertical vent pipe. I was planning two pipes to allow air to flow in one and out the other.
My plan was to lay out a rectangular circuit of pvc pipe with holes in it under the foundation. On each end of the rectangle I would have the pipes joined to a sanT that goes straight up thru the walls and out the roof. On one I was going to install a fan to pull the air out.
After some reading g on the internet this morning I can't find any examples of an inlet hole in a radon pipe design. They all have one pipe. It seems that it would be like sucking on a bottle. Without air flow how could this work? Also, would the inlet pipe introduce moist air into the gravel below the slab and potentially cause a problem? Anybody have experience with this?

Thanks in advance.

 

[fried1765]

As part of my new home build, I am installing a radon mitigation system. The information I have been reading suggests that I only need a single vertical vent pipe. I was planning two pipes to allow air to flow in one and out the other.
My plan was to lay out a rectangular circuit of pvc pipe with holes in it under the foundation. On each end of the rectangle I would have the pipes joined to a sanT that goes straight up thru the walls and out the roof. On one I was going to install a fan to pull the air out.
After some reading g on the internet this morning I can't find any examples of an inlet hole in a radon pipe design. They all have one pipe. It seems that it would be like sucking on a bottle. Without air flow how could this work? Also, would the inlet pipe introduce moist air into the gravel below the slab and potentially cause a problem? Anybody have experience with this?

Thanks in advance.

Helped my son in Atlanta install a system 3 years ago.
You only need one pipe (exhaust) with a fan.

 

[WoodChuckDad]

Thank you, Fried. I guess I will just go ahead and get it laid out. It seems pretty straightforward.

 

[RNeumann]

You are way over thinking this! Dirt is porous and the off gassing is so minute that that’s all the “flow” it needs. Surprising, but the engineers and drawings you found are correct.
When I do this-
One horizontal pipe with holes under the floor running say 1/3 or so of the length of the building (raised or slab). This has nothing to do with the foundation btw. 90° up through the floor and into a wall- if it’s a slab obviously placement is critical. Take the pipe through the roof and vent like the rest of the plumbing.
The crawl space or slab will need a sealed vapor barrier- this is 99% of the radon reduction.
I use the heavier green vapor barrier plastic, 4” SDR35/3034 perf pipe and reduce down to a 2” vent that matches the rest of the plumbing pipe- PVC or ABS.

If their is any chance of underground moisture you can take the other end of the perf pipe and daylight it to the same location (not same pipe!) as your gutter and foundation drains. This will act as a big under slab/floor french drain.

 

[BoylermanCT]

What has been shared is correct, you only need an outlet pipe no inlet pipe. If you want two pipes, you could have two systems, one on each end of the house. I have a radon system that was installed on one side of the basement. But having another one on the other side, 60 feet away might not be a bad idea. Radon is a silent killer so you can't remove too much of the gas! You may also want to consider a radon system for your water. If it is in your water, it get released when the water comes out of the tap or shower head.

 

[Lemo]

You might look into a product called form-a-drain if you aren't too far along. I used it when we built several years ago and just have one 4" pipe for radon evacuation. It functions as a form to pour the footings and is left in place.

 

[oosik]

I simply put a low velocity fan in one of my basement vents. My basement is unfinished with a gravel floor.

 

[Firemanbuck82]

Radon is a silent killer

To be fair, radon isn't toxic, so it doesn't kill you like chlorine gas would. The cancer you get from breathing it for years might kill you though.

 

[chim]

About 7 years ago I contacted Val at the website below. He had me gather some information and advised how to install a system myself. I did as instructed and all is well now.

Indoor Air Pollution, A Major Source of Health Problems

 

[ADSNY]

As has been said, you don't want two pipes. The principal behind Radon mitigation is putting the sub-slab area under a negative pressure (ie. vacuum). If you have an inlet pipe, you will A) not be allowing the sub-slab to depressurize; and B) creating a loop that most likely will not communicate with all areas under the floor/membrane.

Also, make sure the radon fan is mounted outdoors. That way, if its discharge pipe is ever accidentally disconnected you won't be filling your house with radiation.

 

[rd_macgregor]

I wonder if a wind-powered turbine vent would do well enough (at some locations, anyway), rather than have a powered fan going all the time?

 

[Sawyer Rob]

Whether you need an exhaust fan or not, depends on how much radon you have...

Last house I was involved in, HAD to have a fan to meet code... and that was in up state NY.

SR

 

[WoodChuckDad]

As has been said, you don't want two pipes. The principal behind Radon mitigation is putting the sub-slab area under a negative pressure (ie. vacuum). If you have an inlet pipe, you will A) not be allowing the sub-slab to depressurize; and B) creating a loop that most likely will not communicate with all areas under the floor/membrane.

Also, make sure the radon fan is mounted outdoors. That way, if its discharge pipe is ever accidentally disconnected you won't be filling your house with radiation.

I went with one pipe because that is the prevailing method. But I question the negative pressure concept of one pipe and no inlet for air. Mostly because of experience with a wood shop and saw dust collection. When you collect dust from a closed saw table you get the most effective dust collection by having a vacuum pipe attached and an inlet for air. Air flow makes the system much more effective. You still maintain a negative pressure environment but you have air movement which makes the system work much better.

 

[ADSNY]

I went with one pipe because that is the prevailing method. But I question the negative pressure concept of one pipe and no inlet for air. Mostly because of experience with a wood shop and saw dust collection. When you collect dust from a closed saw table you get the most effective dust collection by having a vacuum pipe attached and an inlet for air. Air flow makes the system much more effective. You still maintain a negative pressure environment but you have air movement which makes the system work much better.

Difference is, with a shop vacuum setup, you know the pathway of the contaminants you want to remove. Under a slab, you have no idea and may be bypassing the source of the radon by giving the air a path-of-least-resistance to follow.

 

[Sawyer Rob]

I went with one pipe because that is the prevailing method. But I question the negative pressure concept of one pipe and no inlet for air. Mostly because of experience with a wood shop and saw dust collection. When you collect dust from a closed saw table you get the most effective dust collection by having a vacuum pipe attached and an inlet for air. Air flow makes the system much more effective. You still maintain a negative pressure environment but you have air movement which makes the system work much better.

SO, you think it's the same, to pull sawdust through a solid floor/metal cabinet, as it is to pull a gas through porous dirt??

No comparison at all...

SR