radon mitigation

[Case]

My house a a radon level of 2-4 pCu/L, with long term readings being in the lower 2s but it's hard to be certain since I frequently open basement windows when it gets higher.  I know that 4 pCu/Li is the EPA recommended action level and that the link btw low radon exposure and lung cancer is speculative, but I tend to want to err on the side of caution.  As I have monitored the radon level for he past year, but I have learned is that the biggest impact on the radon level is whether the ground is saturated or not.  So radon does up in wet periods, is higher in the winter, and can get really high (4-8) if there are large volumes of rain, or the ground is covered with snow.  All of this indicates the radon seeps in most when it cant easily escape the ground around the house.

I have a 1950s house which was renovated.  The basement is just carpet on top of a concrete floor, with cinder block walls (with drywall on top).  There is no vapor barrier.  There are a couple obvious things to do like seal the sump pit, and seal cracks.  However, I can't get to almost all of the walls since they are finished.  I could pull up all of the carpet if I had to.

I have talked to a few companies about sub-slab depressurization systems.  Most companies wont warranty below 4 pCu/L (long term reading) and only one would warranty to 2 pCu/L.  Therefore, I have no guarantee from any company that what they install will actually help my situation.

So, what I am trying to learn here is:
-Do standard approaches of sealing cracks/etc... make much of a difference, or does everyone just end up at a sub-slab system if they want to have much impact?
-any personal experiences you have in reducing radon levels would be valuable to hear about.

Thank you!

[NorCal]

No specific advice, but can I ask what you're using to measure radon? 

I've been wanting to measure the radon in my house for a while, but I've read a lot of reviews that claim the home monitors are largely worthless for getting an accurate reading.  Maybe I'm just looking at the wrong products.

The little I've read really indicates that every house is different, and there's really no way to know what will work unless you try it.  I would start with the cheapest potential solutions and work up from there.

[former player]

I would suggest continuing with your ventilation strategy - it's good not just for radon but for all the other pollutants that come from furnishings, cleaners, clothes, and so on.

I wondered whether improving drainage of the land outside the house might help?  But not when you have deep snow, and on a slab built house changing the saturation levels of the land might have effects on the foundations.  Sealing cracks is cheap and can't do any harm.

I don't have a basement, my house had moderate radon readings when I moved in, with the readings being taken with little ventilation.  I've incorporated sub-slab pits and venting in renovated rooms and make sure the one ground floor room still in original condition (it has a suspended wood floor) is well ventilated. I keep doors and windows open as much as possible in summer and in winter as much as is compatible with staying warm while not spending too much on heating, but I'd probably do that regardless of radon because I'm near the sea and need to keep ventilating so as not to have bad effects from the humidity.

[Case]

No specific advice, but can I ask what you're using to measure radon? 

I've been wanting to measure the radon in my house for a while, but I've read a lot of reviews that claim the home monitors are largely worthless for getting an accurate reading.  Maybe I'm just looking at the wrong products.

The little I've read really indicates that every house is different, and there's really no way to know what will work unless you try it.  I would start with the cheapest potential solutions and work up from there.

I am using the Airthings Corentium.  It gives both a long term average reading, as well as 1 and 7 day readings.  I've read that it's legit.  Expensive but worth getting if you want to know.

[Case]

I would suggest continuing with your ventilation strategy - it's good not just for radon but for all the other pollutants that come from furnishings, cleaners, clothes, and so on.

I wondered whether improving drainage of the land outside the house might help?  But not when you have deep snow, and on a slab built house changing the saturation levels of the land might have effects on the foundations.  Sealing cracks is cheap and can't do any harm.

I don't have a basement, my house had moderate radon readings when I moved in, with the readings being taken with little ventilation.  I've incorporated sub-slab pits and venting in renovated rooms and make sure the one ground floor room still in original condition (it has a suspended wood floor) is well ventilated. I keep doors and windows open as much as possible in summer and in winter as much as is compatible with staying warm while not spending too much on heating, but I'd probably do that regardless of radon because I'm near the sea and need to keep ventilating so as not to have bad effects from the humidity.

In regards to improving drainage, I think I am just about maxed out.  I live on the top/side of a hill, so the front of my house should be as well drained as is possible.  The back does get some water accumulation in heavy rains, so I could pursue a french drain system to improve that.

Since I am on the east coast, keeping windows open tends to increase humidity.  I use a dehumidifier in the basement, which is critical.  Keeping the windows open thus contributes to heating/dehumidification costs, though I'm mostly ok with that.  But nonetheless, 'zero' radon is the only safe radon, so I'll continue to pursue this off/on.

[lthenderson]

The farmhouse I grew up in, built in the early 50's, had a radon level somewhere around 8.0 in the basement. My folks hired a company that dug a trench through the concrete around the slab perimeter and buried a pipe hooked up to a pump that removes the air and exhausts it outside the house. The radon levels went down to something like 0.2 after that.

I would worry that just opening up windows (especially if you are referring to egress windows or little ones up near the top of the basement wall) would do little to the actual concentrations at floor level as radon is heavier than atmospheric air.

[jessetayriver]

Hi,
I'm new to the forum but have been reading MMM for quite a while.

Some quick points:

In most cases, site drainage should massively prioritize the footprint of the house over groundwater around the site. In 1.5" rain, each horizontal square foot will receive ~1 gallon. This generally means that several downspouts will see hundreds or potentially thousands of gallons of water depending on the severity of rain in your area. Eject downspout water to daylight >10' from the house where the grade slopes away. Check to ensure there are no roof bypasses (flashing, gutters, etc) that bypass the collection system. Position downspouts to where water is easily managed rather than fetishize aesthetics and symmetry.

A sizable number of basements are depressurized by the operation of an HVAC system that is located in the basement. This is because return panning is historically significantly more leaky than supply, and often constitutes a considerable fraction of overall system airflow. IOW, a lot of HVAC systems 'suck' on the basement, which greatly increases radon infiltration. You can quantify this by turning on your furnace/AC, closing the door behind you on the way down the basement stairs, and placing your hand at the base of the door. If you feel air pulling across the bottom of the closed door, your basement is probably depressurized by the equipment. The good news is that this is fairly easy to fix. Either leave the door slightly ajar (use that thing at the top of the door that people use for cats or whatever) or install transfer grilles in the basement stairwell.

[NaN]

My house a a radon level of 2-4 pCu/L, with long term readings being in the lower 2s but it's hard to be certain since I frequently open basement windows when it gets higher.  I know that 4 pCu/Li is the EPA recommended action level and that the link btw low radon exposure and lung cancer is speculative, but I tend to want to err on the side of caution.  As I have monitored the radon level for he past year, but I have learned is that the biggest impact on the radon level is whether the ground is saturated or not.  So radon does up in wet periods, is higher in the winter, and can get really high (4-8) if there are large volumes of rain, or the ground is covered with snow.  All of this indicates the radon seeps in most when it cant easily escape the ground around the house.

I have a 1950s house which was renovated.  The basement is just carpet on top of a concrete floor, with cinder block walls (with drywall on top).  There is no vapor barrier.  There are a couple obvious things to do like seal the sump pit, and seal cracks.  However, I can't get to almost all of the walls since they are finished.  I could pull up all of the carpet if I had to.

I have talked to a few companies about sub-slab depressurization systems.  Most companies wont warranty below 4 pCu/L (long term reading) and only one would warranty to 2 pCu/L.  Therefore, I have no guarantee from any company that what they install will actually help my situation.

So, what I am trying to learn here is:
-Do standard approaches of sealing cracks/etc... make much of a difference, or does everyone just end up at a sub-slab system if they want to have much impact?
-any personal experiences you have in reducing radon levels would be valuable to hear about.

Thank you!

Wow, if my house was down to 2 pCu/L I would be thrilled. Really, why bother?