Mitigating Radon From Crawlspaces

[@buzzkil419]

General Electric is offering to put a system in my basement but my house has two crawl spaces and a slab in between them that is about 3 ft lower in grade and the house was built in 1880 with a stone foundation so I don’t know how well they could seal a piece of plastic down there

[@mardigrasw]

What brand plastic?

[@hrned]

I have a crawlspace that has dirt on about half (700 sf) and slab on the other half (another 750 sf). I understand the basics for covering the dirt, but do I need to anything for the slab portions? Also, do you recommend 20 mil cross-fiber plastic or will 6 mil do? Last, do I need to use hard pipe, or will perforated drain pipe (black, corrugated) suffice?

[@douglaskladder637]

Often both foundation areas are treated with a common depressurization system (i.e. fan and vent pipe). However, if you have time you may want to phase this with and treat the crawlspace first as that often provides the greater reduction. But plan out your system such that if you also need to treat the adjacent slab, the depressurization system can be extended to a slab core. 20 mil is typically not necessary. The determination is how likely the poly is to be damaged with traffic in the crawlspace such as accessing a low boy furnace in the crawl. 4-6 mil reinforced poly is very common. Perforated and corrugated drain pipe is fine for under the poly sheeting. However, any portion of the vent piping above the poly and routed to fan and above fan should be solid, schedule 40 PVC or ABS. 4-inch diameter is most common. You want smooth wall pipe to reduce air flow restriction and noise. Also, a fair amount of condensation will occur in the pipe so be sure joints are primed and glued well and pipe slopes back to suction point so water does not accumulate.

[@hrned]

@@douglaskladder637 Thank you very much for your comprehensive response. I am going to check out your website, but is there a rule of thumb of the amount of corrugated pipe/square foot?

[@acousticgreg1]

What kind of caulking did you use? Where can I pick some up?

[@RadonCerti]

Greg: The caulk most commonly used is polyurethane. One brand name is Sikaflex. All of the radon supply houses like Professional Discount Supply and Radonaway carry it as well as you can often find it in the large box stores. But I would check with the specialty supply places as they will also have the right fans, labels, performance indicators, etc. There are also been improvements in some of the tapes that the polyethylene suppliers make that are quite good-but be sure it is compatible with the poly you use and the type of foundation walls you have.

[@gearheadcg]

Does a crawl space system have to have a u gauge ?

[@RadonCerti]

If the crawlspace system utilizes a depressurizatiuon fan a U-tube or similar performance indicator would be needed. The performance indicator is intended to indicate if there is a problem with the radon fan. Since a radon fan is used on a crawlspace system or a slab system or a sump system a U-tube would be needed in all three cases

[@gearheadcg]

@@RadonCerti this one is a submembrane system I believe

[@JasonBerg-v1q]

Dam that is pay someone to do that work

[@thefooshisloose]

If you are a white collar who has never seen a hard days work and thinks a 3 hour day is long then yes, you should pay a real person to do that work for you. No one wants to purchase your house full of Radon when you go to sell it and you have done a half a$$ed job in the basement because you think it is underneath your pay grade so yes please pay someone to do that work for you.

[@berthull9333]

Once the pressure on each side of the fan equalizes there will be no air flow. Let's do this a lot simpler: Why not just open up a couple wall vents? In extreme cases you can install a powered fan in one of the the wall vents so that fresh air is continuously exchanging with crawlspace air.

[@djo9c1]

Additional fresh air (lower in radon) will be pulled through porous soil to displace what the fan is pulling up.

[@kg4lod]

All things are tradeoffs. Vented crawlspaces cause high energy bills and mold problems. They're much more vulnerable to termites and other pests. Vent fans in vented crawlspaces are much less effective against radon than sealed crawl spaces because radon gas is heavier than air. The lighter air is moved by the fan and the radon stays concentrated below the living spaces of the home.

[@berthull9333]

@@kg4lod if the radon gas is heavy and doesn't get moved by the fans, then how would it cause a problem in the living space?

[@kg4lod]

@@berthull9333 Radon gas emits (radiation) a small amount of high energy particles that can penetrate and damage your DNA (gamma particles, like X-rays). Living on top of a radon gas cloud isn't a good idea. You're correct that, in general, vented crawlspaces have lower radon concentrations than sealed crawlspaces, but vented crawlspaces pose significantly greater risks to the health of the occupants and longevity of the structure through other hazards like mold, moisture-related rot, and pests. Vents are hit-and-miss. If they don't offer enough passive airflow or create dead spaces, radon can accumulate -- and adding a vent fan at that point is unlikely to be very effective (unless you seal up the vents and incorporate the crawlspace into the conditioned building envelope). The vent fan in a vented crawlspace is more likely to more nitrogen (e.g. air; 28 atomic mass units) than radon (222 atomic mass units; 10x heavier). To move heavier gases, you need to develop significant static pressure which (practically) no vent fan can do in a cavity freely exchanging with the open atmosphere.

[@thefooshisloose]

You can't just "simply" try to force the air out as described in this elementary fashion. It is much more complicated than this and due to fresh air returns and window proximity you will end up making things worse by pumping the air directly into the living space. This system needs to be engineered for the whole home system and not just a short sighted "get the radon out" type of approach. Radon is a very serious problem in some areas and is not taken seriously enough for the health of families especially in areas where they don't understand it due to lack of literature.

[@jeff5101]

what a scam industry

[@goat9199]

#deadnow

[@rekostarr7149]

@@goat9199 ahahaha

[@thefooshisloose]

Filed bankruptcy in 2023 due to radiation chemo therapy from all the years of huffing radon gas. Wife divorced him, kids changed their last name, even the dog ran away due to OP being an ignorant a$$clown on a biblical level. RIP when you are 6 feet under brother, maybe only then will you have peace with this world.

[@thefooshisloose]

@@goat9199 #natural_selection