High radon test results and remediation?

[A930Rocket]

My parents are selling their house in Atlanta/Dunwoody and they have an offer on the house, conditional on the inspection report and radon test results.

The house is on a full finished basement and there are two HVAC systems, one for the second floor and one for the first floor/basement as well. The basement does not have a thermostat and temperature is based on the second floor thermostat.

The house is 45 or so years old and it has typical issues for his age. Nothing insurmountable there. The bad news is that the radon test came in at 8.XXX.

Has anyone dealt with high radon numbers and is there any remediation possible to lower the numbers quickly?

[island911]

Air exchange.

Radon is a gas that that comes in through the ground due to the lower partial pressure of a heated space.
SO perhaps a HVAC system that pushes positive pressure on the house. (?)

That's all I know. Never had to deal with it.

[Z-man]

Remediation is possible. My home had high radon levels when we inspected it upon purchase. The house was already built with contingency in place, but not fully hooked up.

My system: a cavity is created under the basement floor. an open PVC pipe runs from that cavity through all floors and up to the attic. This was already in place when we purchased the home. All that was needed was to add a pump (ie fan) to the pipe in the attic, and run the pipe through the roof to vent out the radon.

How the system works: by creating a low pressure pocket under the basement floor, the radon gas will populate that space. It will then get pulled out of that cavity by the vacuum created by the fan in the attic. The fan continues to push the radon out through the roof. Since installing the system, my radon numbers have been in an acceptable range.

For your parent's home, they will likely need to bust through the basement slab to create a similar pocket. Then depending on the house size and ability, they will run a PVC pipe either up through the roof, or out the side of the house. Either way will work, but roof exit is more ideal.

I will take some pictures to illustrate the system...

[reachme]

Yes best is probably to bust through the floor but as said above Radon is a gas and there is a reason they tell you to take the test with the basement windows closed. Open windows dissipates the gas.

My readings were on the edge 16 years ago when I bought but it was new construction so no settlement cracks in concrete. Since then I keep basement windows open as often as I can. I've retaken several times (closed windows) and still at or below. I've read it can vary naturally quite a bit in the same basement even over a short time

Any kind of air exchange under floor or not in the basement will lower your numbers. If you have well water coming in that could be another source

[cabmandone]

https://www.amazon.com/The-Original-Radon-Sump-Dome/dp/B00A422NV8/ref=asc_df_B00A422NV8/?tag=hyprod-20&linkCode=df0&hvadid=193994427542&hvpos=&hvnetw=g&hvrand=11353125936473712210&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015981&hvtargid=pla-313394905846&psc=1

Once you've done that, epoxy the saw cuts in the floor. Saw cuts, cracks in the concrete and the sump pit are the easiest paths for radon to enter.

[masraum]

I guess "Flex Seal" isn't an acceptible solution? If you can make a boat out of a screen door...

[MBAtarga]

Our house has a mitigation system that was installed when the house was built. I'm not sure how involved installation after build would be. Our system has a suction pipe under the basement slab as well as high on the wall leading under the garage slab which is level with the 1st floor - it all expels on the outside wall at the basement entrance.

[Chocaholic]

We had one put in a few years ago. No big deal and not very expensive. Exactly as others described. As I recall cost was about $1800. Ours wasn’t even very high but we we did it for peace of mind.

[A930Rocket]

Great ideas guys. If I’m not mistaken, there’s a chase already from the basement to the attic, I would just have to look at it and see.

With a finished basement, how big of a space or void would we need under the slab? Would it need to be centrally located or is it OK to have it offset?

[A930Rocket]

Originally Posted by Chocaholic

We had one put in a few years ago. No big deal and not very expensive. Exactly as others described. As I recall cost was about $1800. Ours wasn’t even very high but we we did it for peace of mind.

Choc, can you PM me any details for somebody in Atlanta?

If the contracts go through, we are supposed to close October 15, so I’d like to get this done quickly.

[A930Rocket]

I’m guessing it’s 3500 ft.² plus.

My crude drawing shows the basement. It has a storage room at the front left, storage room at the right rear, and a 3 x 4 closet under the stairs. The green square is the chase from the basement to the attic.

The basement goes from the left of the bay window, to the right side. The left front storage room is under the area of the left side gable.

[dad911]

When was your house built?

Since the late 80's we have been roughing radon systems in new construction.

Poly under the slab, 1 pipe per 1500 SF of basement to the attic, through the roof. Only nee to add a fan.

On an older home, typically drilling a hole in the slab, PVC pipe to attic/above roof, and a fan will drop radon level.

[A930Rocket]

Originally Posted by dad911

When was your house built?

Since the late 80's we have been roughing radon systems in new construction.

Poly under the slab, 1 pipe per 1500 SF of basement to the attic, through the roof. Only nee to add a fan.

On an older home, typically drilling a hole in the slab, PVC pipe to attic/above roof, and a fan will drop radon level.

1976. Radon was unheard of back then.

[dad911]

In that case, probably have to drill a hole in the slab, and pipe it out with a fan. Plenty of diagrams on the web.

If you have a sump pit, it needs to be sealed, and you can connect the pipe and pump from that if convenient.

In the 70's, we used to put an expansion joint around the slab next to the wall. If you have that, you need to seal it, with a backer rod and caulk. Also caulk any cracks in the slab.

[A930Rocket]

Originally Posted by dad911

In that case, probably have to drill a hole in the slab, and pipe it out with a fan. Plenty of diagrams on the web.

If you have a sump pit, it needs to be sealed, and you can connect the pipe and pump from that if convenient.

In the 70's, we used to put an expansion joint around the slab next to the wall. If you have that, you need to seal it, with a backer rod and caulk. Also caulk any cracks in the slab.

It’s a finished basement. The only two areas not finished are marked ST. The rest is a bathroom/BA, bedroom/BR and the open area.

[HardDrive]

Sellers condition statement: "XXX radon level detected during testing. Seller will not remediate, buyer should factor condition into purchase offer if they feel condition is important."

Move on.

[A930Rocket]

Originally Posted by HardDrive

Sellers condition statement: "XXX radon level detected during testing. Seller will not remediate, buyer should factor condition into purchase offer if they feel condition is important."

Move on.

They already agreed to our full price. Now it’s a matter of negotiating home inspection repairs and the radon test.

I told my brother, let’s come up with a number we can all agree on for repairs and sell it. I live six hours away and nobody has time to fiddle with it.

[dad911]

IDK about Georgia, but in NJ even though we rough a system during new home construction, only a licensed radon remediator or the homeowner can install the fan. Going rate around here is $1400-$2k.

[sc_rufctr]

Yikes... I've never heard of Radon gas in houses.

[LWJ]

Yes. Get a pro system. They are common in high radon areas.