Radon Mitigation in Mobile Home

Well Merry Christmas to me!

Well let's just say I'm not having a great day today. After my sister has just completed some wildly expensive radon mitigation in her home as her radon levels where astronomical (~ 1400 Bq/m3), I finally set up the radon monitor at our house and the first night of measurements is NOT looking good at all (~539 Bq/m3).

I'm not sure why I had the impression that radon was not an issue in mobile homes (due to a lack of a foundation) but I was very wrong. All my knowledge for radon mitigation is for homes with a foundation or basement/crawlspaces.

Any advice for short term and longterm mitigation strategies for radon levels in a mobile home?

For short term all I can think of is opening up some windows, but I live in Canada and it's currently winter! Which I'm fine with layering up but I also have a 10 month old baby, so I also need to keep her cozy but also not lose my mind thinking about the impact of radon on her health.

For long term solutions, all I can think of it ripping up our flooring and installing new barriers underneath?  

Any help is appreciated! I'm also going so start my own research and I'll post any findings here!

While I don't have specifics because it will come down to your concentration, I do have some positive news.

You are not alone.

The only way mobile homes will not accumulate radon if present is if it doesn't have skirting. With skirting, now you have a place for accumulation to happen and it to seep into your living spaces.

I'm not sure what kind of venting system your mobile home has, or if it has one, but to fix this issue you will have to have some kind of ventilation system installed to prevent the accumulation. This can be done in addition to sealing up cracks/crevices that are in your floor.

Don't let this crush your Christmas celebration, if anything its good that you have caught onto this invisible risk!

Hi Ashley,
I've tried to find some information for you, and it seems to come down to floor construction and ventilation.....

From wikipedia Radon

The four principal ways of reducing the amount of radon accumulating in a house are:[10][163]

Sub-slab depressurization (soil suction) by increasing under-floor ventilation;
Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms;
Installing a radon sump system in the basement;
Installing a positive pressurization or positive supply ventilation system.

They also say earlier that is is the decomposition products ("daughters") that are the risky chemicals, rather than Radon as such. Also that they stick to dust particles and have an electrostatic charge. Using that charge to 'capture' the daughter chemicals doesn't seem to be a method of control though - I guess because you would be concentrating the chemicals in capturing them and then have to dispose of a radioactive waste somehow.

If you have a gap under the moblie home that would be like having a crawl space right?

Homes built on a crawl space may benefit from a radon collector installed under a "radon barrier" (a sheet of plastic that covers the crawl space).[10][165] For crawl spaces, the EPA states "An effective method to reduce radon levels in crawl space homes involves covering the earth floor with a high-density plastic sheet. A vent pipe and fan are used to draw the radon from under the sheet and vent it to the outdoors. This form of soil suction is called submembrane suction, and when properly applied is the most effective way to reduce radon levels in crawl space homes.

Don't panic though - they also say that the concentrations can vary a lot over time, so your exposure may be less than you think (or of course more :( ).

This is the UK Radon site and they recommend "Mechanical under-floor ventialtion or Natural under-floor ventilation" for concentrations of Radon above approximately 500 Bq /m3 for dwellings with suspended floors.

How do you heat?
A warm home in a cold climate will naturally breathe from the bottom up, because convective pressure pushes warm air out the top and pulls cold in the bottom - unless you make it do something else. If you have a heating appliance that vents combustion air but doesn't have it's own makeup air, this will add more negative pressure to your home, which just adds more to the pressure gradient. In some cases, poor ducting design (ex: improperly sealed return air ducts that run underneath a home) can alone be a big concern.

Assuming the radon is being pulled up from underneath - Opening a window should significantly decrease the pressure differential between your home and outside, which should significantly decrease the amount of air that gets pulled in from underneath. It should markedly reduce radon levels in pretty short order - BUT - underneath will often be warmer than outside this time of year, which means that space will make it's own convective pressure and want to push radon contaminated air up into your house no matter what.

Radon is considerably heavier than air, and can absolutely collect in the void under a skirted home. Add negative pressure to the home, and you've given yourself a radon reservoir to suck air from. If your house is skirted, that skirting should be ventilated. It's not uncommon to see a skirting job where someone did everything in their power to seal under the home 100%, and I get it, heating is expensive. That space *needs* to breathe though, for radon and moisture dissipation purposes.

Be careful, because frozen plumbing sucks - but if you're skirted, and that skirting doesn't have any visible gaps/open seams/vents, I would add a few small vents to allow underneath to passively breathe on it's own.

Long term? It might not be a practical job in the winter, but laying a vapor barrier underneath the home that extends past the skirting can allow you to keep underneath nearly completely sealed (which is good for the heat bill) without risk of ground vapor (radon or water) accumulating. Be careful - adding vapor barriers wrong can cause unexpected moisture issues, and bad vapor barrier installations kill a lot of structures by inducing rot where it wouldn't otherwise have occurred.

My under skirting is made of soffit vent vinyl.It has perforations in it for ventilation,apparently it wasnt enough ventilation because a big wind blew some of it in and under the home.I put some back but left a few pieces out for more ventilation.I dont have extreme cold here so i dont worry about pipes freezing very often although they have,they are pex or black plastic and dont burst so its not a huge issue for me but if you are worried about radon this might be a solution,just taking one out of each end might be enough for getting rid of radon but still keep in some warmth from the ground.Just keep your water running in extreme cold.

How good is your radon monitor? Are you sure it is accurate?
Before you spend lots of money/effort, should you get a second "opinion"?

Thanks everyone! I will keep doing more research but it seems like it may be a summer project to address a vapour barrier under the floors/home. I have cracked open the windows in the nursery a little. We will have to see if that helps the readings.

We have both a furnace and a wood stove for heating in the winter. The furnace duct runs under the house as well as the plumbing so I think that it would make the most sense to address the vapour barrier under the floors as well as and cracks/seams in the furnace ventilation.

It's usually super windy here, and we definitely could feel the cold air running under the house via our frigid floors on those days. I'm guessing maybe we can figure out some sort of venting under the home for the winter season that doesn't depend on their being 80 mph winds!

As far as I know, the radon monitor is of good quality. It's my Dad's. My sister's was consistently reading around 1400 br/m3 and after addressing the basement ventilation (sub-floor pipe to collect and vent the radon), pouring a new layer of concrete, and sealing any cracks they were able to get it down to below 75 bq/m3 before they had even installed a vapour barrier yet!  

Yes, a problem to be addressed.

No, not a life-threatening emergency that should interrupt your sleep.

I have this notion of adding vents to the skirting and redirecting the bathroom fan to ventilate the space. My 2c.

Well cracking the windows has reduced levels to about 290 bq/m3. We've been having a mild winter so it hasn't been too much of an issue with reducing the temperature in the home.

We are going to place the monitor under the house to see what readings are like this week.

What about putting a simple vent fan (or fancier radon fan) that just gently sucks air from the crawlspace and blows it outside?  If it sucked too much air out it would get replaced by the frigid outside air and maybe cool the floor off too much and freeze pipes.  But a gentle bit of suction may remove the radon before it rises up into the house...

Ashley,

I was about to mention venting the crawlspace but I see that Mike beat me to it.  Definitely talk to someone more knowledgeable than me, but my two cents says that venting will do a lot to get rid of the radon problems.  Maybe you can really seal up the underside of the home itself?  But that’s probably a job for spring.

Eric

Mike Haasl wrote:What about putting a simple vent fan (or fancier radon fan) that just gently sucks air from the crawlspace and blows it outside?  If it sucked too much air out it would get replaced by the frigid outside air and maybe cool the floor off too much and freeze pipes.  But a gentle bit of suction may remove the radon before it rises up into the house...

Yes, we are thinking along those lines. I'm not sure if also a fan that collected hot air from above our wood stove that went vented to under the house with additional vents in low points of the skirting would allow for warm air to be blown under the house and help vent the heavier radon gas at the same time?

Would a black plastic barrier on the ground under the house keep the radon in the ground rather than it rising up into the floor? I have no idea if this would work but it might help,perhaps someone with a better understanding of the situation would know.

It should.  I know someone with a crawlspace under a house that has radon.  The official fix is to put plastic down on the ground, seal it to the perimeter of the foundation to keep the gasses out of the crawlspace, and add a perforated pipe under the plastic with a fan to suck the radon out and blow it outside somewhere.

I'm sorry to hear about the high radon levels in your home, especially with the added concern of having a young child. It's crucial to address this issue promptly to ensure the health and safety of your family.

Depending on the construction of your mobile home, you may be able to make modifications to the foundation to improve ventilation and prevent radon infiltration. This could include installing vents or creating additional barriers to radon entry. It's important to note that radon mitigation in mobile homes may require different approaches than traditional homes with basements or crawl spaces. Consulting with a professional and conducting thorough research will help you identify the best course of action for your situation. Additionally, regularly testing radon levels after implementing mitigation measures is essential to ensure effectiveness and ongoing safety.

While any thoughts, talk or reading on any sort of radiation is scary, the science I have read says that there is an endemic level of background radiation which needs to be subtracted from any readings.  And serial readings need to be done, not cumulative readings.  First and foremost, any natural product such as plaster (gypsum) plaster wall board and earth or rock will give off radon.  Our house is compressed earth with slate floors so should be radon central.  Good ventilation is the easiest way to drop the levels in the areas of collection.  

I am assuming that a mobile home is one that is on a trailer chassis.  If the floor is sitting directly on the Chassis, you can simply add an underfloor of wood and put expanding poly urethane in the gap to seal it.  A larger gauge architectural mesh can be used as the siding between the under floor and ground area rather than a solid siding.  Let nature do the ventilating.

I am an eternal skeptic.  If some one is touting something is dangerous - what is the evidence?  People have lived in the earthen environment since time immemorial and there does not appear to have been galloping lung cancers back when....  My reading of the tea leaves is that smoking in the presence of very high concentrations of radon may increase the risks from smoking.  But there is no empirical data I could find.

My eternal skeptic brain also says that if that same someone is touting the solution such as plastic lining, fans and other expensive gadgetry, it is so they can make a shed load of money.  I wonder whether the gasses given off from plastics, plasticisers  and glues/ sealants are less toxic than radon?

Kids play in the dirt, get dirty and are exposed to a huge variety of different chemicals and decaying minerals, fungi, germs and other micro organisms on a daily basis.  For my money and from my experience, ventilation in and around the home is the best and most natural solution.  As we go through winter, internal toxins, radon, mould spores, plasiticisers, bacteria and the like will build up.  If the day permits, open the doors and windows in one or more rooms in rotation to vent them.  Come summer, all will be good to open up.

I cannot remember which plants they are, but there are some that will take up toxins within the home, acting like a natural cleaner.  With a bubs that is likely to be into everything, the plants can be hung in baskets out of harm's way.

In short, my advice is to do your own research on accredited national radiation sites (ours is arpansa) , ensure that the cure is not worse than the problem and look for natural solutions first.  Above all, consider that someone flogging a great solution is only out to line their pocket at the expense of yours.

Hope this will allay some fears.  Good luck with it all.

The plant from my post above is philodendron.  My wife says that we have had them in a few houses we lived in.
Here is a site which may be useful in the discussion: https://www.petalrepermies.com/philodendron-benefits/

Paul Fookes wrote:The plant from my post above is philodendron.  My wife says that we have had them in a few houses we lived in.
Here is a site which may be useful in the discussion: https://www.petalrepermies.com/philodendron-benefits/

I'm down for any excuse for a new house plant!