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I ran a radon test and found it to be 16 piC/l, four times the level at which they suggest performing mitigation, 4.0 piC/l. I had the crawl space vents blocked. I opened up the vents and retested and it is now 5.5 piC/l, closer to acceptable.

My crawl space is a 4' high over a dirt base. If I remember correct there is a plastic visquine layer under the dirt. There are 4 small vents in the foundation.

When I added the chimney cavity 20 years ago I ran a full length PVC pipe in it from the base of foundation out the top of this chimney chase. It is not connected to anything.

Is there anything I should try before going to the effort of full mitigation? Considering just opening the vents reduced the radon to a 3rd of its previous level, I was thinking some sort of fan in one of the vents pushing air out might make the difference.

 

[Bud9051]

Radon mitigation involves depressurizing the soil below a slab or plastic covering, not just exhausting bulk air. Basically it removes the radon before it enters the crawl.

If you do indeed have "a plastic visquine layer under the dirt" that might work, however I'm not sure why they would put the dirt back down there. Find a spot and do some digging to determine the presence of a plastic layer and what type of soil is down there. Best to have a layer of gravel so any depressurizing will allow radon gas from the entire floor area to move to the exhaust fan.

Do you have any sump pits as they would be an indication of pipes installed around the perimeter of the footings.

Bud

 

[spitz1234]

You could try a erv/hrv that will definitely lower your radon level.

Sent from my SM-G960U using Tapatalk

 

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Do you have any sump pits as they would be an indication of pipes installed around the perimeter of the footings.

Bud

I built the home myself and from what I remember 20 years ago. The excavator dug out for the foundation. We came back from lunch to find a swimming pool where my home was going to be. I live on a creek and the high spring groundwater percolated up without the weight of the soil.

From what i remember we layed down a type of landscaping fabric followed up by some soil to hold down the water. I think there is also a layer of Visqueen somewhere in there its been a long time.

When I had my vents covered my radon was 16.3, when I opened up the vents it dropped to 5.5. Showing simply moving air through the crawlspace dropped the radon significantly. I am hoping a simple exhaust fan drops it to an acceptable level.

I have a lot of things stored in the crawl space. I dread the thought of having to move it all out to install a vapor liner. Also the pipe in the chimney is buried deep in the snow. Both projects would have to wait till spring.

I realized I also have another option. I just had my furnace replaced. There is a 4" ABS pipe still going from the first floor of my home to the roof. I could bring this pipe into the crawl space to vent the radon out.

I hate going into the crawl space but will go down and explore today.

 

[Bud9051]

Wind will blow some air in and out of the crawlspace, but natural air flow through a house is in through lower leaks (or vents), up through the house where it is looking for a way out, this is referred to as "stack effect". I'm concerned that the reduction in crawlspace radon just means that air is now moving through the occupied living space. Where did you take the radon readings, crawl or first floor?

Installing an exhaust fan that blows crawlspace air to the outside will lower the pressure down there and not only bring in more ventilation, but also more radon gas. The idea with mitigation is to capture that gas before it enters the living space and take it directly to the outside.

Where your numbers are on the low side (assuming your measurements were in the crawl) a small exhaust fan may do little harm.

Didn't see an answer to my question about a sump pit?

Bud

 

[Photobug]

Didn't see an answer to my question about a sump pit?

Bud

There is no sump pit.

Our first test was in the living room, first floor of the home.

The second test was a dual test (two testing packs) also in the living room.

The only difference between the two was the open vents in the crawl space. The vents are fairly small and possibly restricted by snow build up this time of year. I think possibly shoveling to clear might get some more circulation through there.

I have two bathroom style exhaust fans sitting around. I am tempted to put one blowing out. Maybe try blowing one out and one in at opposite vents.

I have found a guy that does Radon mitigation and also consulting and sells the fans and equipment for it. I sent him an email to see what he says.

Thans for your suggestions so far Bud.

 

[Calson]

Contact a couple of radon remediation companies and get quotes to see what is recommended and the costs involved. As mentioned, normally there is preparation done while the house is being built if in an area where radon is likely (radon maps are easy to find online).

Post construction with a slab the contractor will cut out a section of the slab and remove dirt and replace it with gravel and then install a vent pipe that will have a powered fan inside it and vent the air to the outside. With a basement they will often drill a hole in the rim joist for a vent pipe. The venting does require the use of an electric fan somewhere in the assembly.

https://www.cpe.rutgers.edu/CT-Radon/downloads/Consumers-Guide-to-Radon-Reduction.pdf

 

[Photobug]

Contact a couple of radon remediation companies and get quotes to see what is recommended and the costs involved.

There is only one Radon company in town. I try to avoid any contractors if I can do it myself, because everything is so expensive in my town.

This my resource for solving my Radon issues.

https://www.indoor-air-health-advisor.com/

The owner is a air quality professional that does consults for free all he aks is I buy my fans and supplies from him.

I am hoping I don't have to lay down a barrier in my crawl space. That will be a major pain. I realize my current vents are almost completely blocked by snow. I am hoping cleaning one of them out and providing a source of exhaust. I will let you know how it goes.

 

[3onthetree]

If you are thinking of just installing an alternative exhaust fan, here's a solution by @HenryMac
https://www.diychatroom.com/f2/radon-mitigation-fan-install-658835/

 

[Photobug]

If you are thinking of just installing an alternative exhaust fan, here's a solution by @HenryMac
https://www.diychatroom.com/f2/radon-mitigation-fan-install-658835/

Exactly what I was looking for. I will measure our vents to see if it will fit. It seems like if the Radon is close to the 4 piC/l level some simple ventilation brings it down to an acceptable level. My only concern is needing to keep the vents free of snow. We have had 300+ inches already this winter.

 

[ColoradoMark]

I installed my own radon mitigation. Even though I have a crawl space, the slab method is all I needed to drop my radon from 9.4 to 2.6

It ain't pretty but it works:

(learn from my mistakes)