if you install a poly but don't seal it, is it there for decoration? it is not a radon barrier, it is no a moisture barrier and it is not a air barrier unless it is sealed!

Let me take a stab at this, (I am sure their are others that could be more eloquent).
There are three major types of nuclear radiation;alpha beta and gamma. Each of them delivering a different "dose". The pipe walls themselves are are shield from almost all of the dose from Alpha and Beta radiation. Shielding for Gamma requires significant layers of lead, or concrete or lots of water. when we did work in the nuclear plants we used lead bricks that were 2"x 4" and could build up a wall to protect workers sometimes several layers thick. the workers building the lead wall would get dosed but that was managed as well i.e. plywood sheets went up then first layer of bricks then second layer of bricks. The workers doing the required work would get dosed at a significantly lower level because of the lead bricks between them and the gamma source. Dose is a factor of exposure level and time exposed. Gamma energy dose is considered to be is straight line from source and distance from source without shielding is a factor for dose as air itself is a shield from gamma radiation.
The gamma radiation from radon emitted while traveling through the pipe, would be partially blocked by the pipe wall itself but most would continue on through, but it would be my guess, there would likely be less gamma transmission through the air than would have been there before SSD system was installed, from the radon decay in air that was occurring.
(that was probably too technical)

Radiation from radon that concerns us most from a health effect point of view is the decay products of radon that because they are electrically charged stick to lungs really well (like a band aid to a hairy arm) and stuck to lungs they will likely cause damage to lung cells as they go through radioactive decay, giving off alpha beta and gamma radiation.
Radon itself will cause similar damage by going through its decay process while in the lungs or while in the bloodstream.

My mentor (Thanks Terry) taught me that Alpha radiation has 30X the relative biological effect to gamma or beta radiation, but only had enough power to penetrate about 1 cell deep. That is why alpha radiation does not cause a lot of skin damage (top layer is already dead cells) but does cause significant damage to live lung tissue. It would be my guess, there would likely be less gamma transmission through the air from the radon inside the piping than would have been there before SSD system was installed, from the radon decay in air that was occurring.

Please do not mistake my belief, I believe that a radon mitigation system with only negative pressure inside the building is a better system, because it prevents errors in the installation from overcoming the good a radon mitigation system does. i just don't happen to believe that it is the system that is required if you have competent professional installers. that are having the quality of thier work confirmed by multiple layers of testing. Soap test fan and joints radon test the building short term and long term.

Rich a great point but were those couplers leaking? i over the last 40 years of being a commercial plumber have or caused to have literally 1,000,000's of mj joints to be installed on cast iron plumbing systems. if they do not leak on installation test they do not leak later. plumbing systems experience much more pressure than our radon mitigation systems do.
i don't know how many fans you have exchanged but my experience is that once a fan is in for even a few days, it is difficult to break that seal even with the stainless steel band removed. While i will acknowledge this is anecdotal it is my field experience.

Doug the big 3 radon fan manufacturers did set up a committee and did develop a method or system for indoor fans for the CGSB standard that was developed in Canada for both existing residential building mitigation and new construction of residential buildings.

What a great question: Here in Canada as a group of mitigators and team teachers we see the ones that excel at learning as the average mitigator not because it is true, but because those are the ones who ask us questions. Marcel and Colin more than Rob, Bruce, Jeff and myself (i use first names because for those that know us that will be enough for those that need last names contact me off this forum), because they are the mitigation instructors, We are the group of the old guard and i am sure that many new people in the industry would not want to ask us for fear we would want to steal their new idea and they haven't yet seen that we have the philosophy that rising tides raise all ships. little do they know that I regularly ask questions of my radon guru's and when it comes to the tough ones i ask a lot of questions of our radon guru's.

When you are doing radon mitigation you are running a lot of radiation through a pipe, it is not unusual for radon concentrations in that pipe to be in the realm of 10-50 thousand radioactive strikes per second. Yet it is extremely common for builders to say i can get my labourers to do that. Lack of knowledge about what we do all the parameters we consider and dismiss, is ignorance not bliss. i do not know how to change the value that others (public, builders, health professionals, government) put on our work of radon mitigation, i do believe that it not understood therefore undervalued. After all it is just nuclear science, and building science that gets run through a pipe. done right it has a great value to society, done wrong it is a pipe sucking on dirt.

The Health Canada dispersion study was the game changer for me when i looked at the data sidewall discharge has very little risk associated with it. Unless someone places little sally's sand box in front of it.

Good afternoon- couple of thoughts This feels like the old list serve with everyone chiming in to help. thank you George for posting this, turned into a really good discussion.
1/ as a plumber who is a radon mitigator i never/ amost never (i have once in 15 years ) use sump lid as my connection point. When you need to get sump lid off in a hurry during a flood they never shut the radon fan off and it can cause back-drafting and carbon monoxide poisoning. Should have known better will not replace Dad or kids..... i know it is allowed but most of my work is caused by builders or site trades not adequately following building code. I will not risk contributing to someones demise because they did not read my nice label on sump lid in an emergency situation.
2/ as a sump lid seal we use a Dow caulking called draft attack (i think in USA it is called seal and peel) it is a removable caulking work great as long as you don't put it between lid and sump. We use sheet lexan that we have supplier cut into 2' x4' sheets for us. get two sump lids out of a sheet and cost are significantly lower than buying sump lid covers. We custom cut it to fit. Always place a warning label.
(we tape the empty caulking tube to sump discharge pipe so they know what they have to go buy to reseal sump lid)
3/ We cut an hand hole into lid with a 4" hole saw and use a 4 inch PVC test plug that drops in and does not need to be caulked in.
4/ if you are going to penetrate the fire wall in the garage, in Canada most have a 1 hr fire rating you may want to install a fire collar on the pipe (not required under Ontario building code ) but we always mention it and customer usually buys it. it is really important to make sure that the opening is sealed (don't want car exhaust to go into basement) and we usually use a fire rated caulking.

Ok i wasn't sleeping i have just been focused on this covid thing ( i think my son has it after a trip to NY state to pick up radon materials).

Rob will tell you that way back in 2005-2008 when we were getting started in the radon industry. I would not install a SSD system with pressurized piping in the building. as a plumber i was concerned not about the quality of my work or my teams work but if we opened the door to interior fans pushing radiation through the interior of a home what would happen when somebody who doesn't have my skill set and knowledge gets in the industry. (Rob said we already install natural gas, propane, furnace exhaust and plumbing in the interior of homes)

Rob quite calmly listened to my rants and said we'll see. Offer it to a hundred customers and we will talk. So i did. slowly the percentages climbed 30% of homes then 50% then..... i think in the last 200 systems we have installed maybe 3 garage style systems with insulated piping in garages and heat tracing (high end homes who did not want noise or no place to exhaust that made any sense). All the rest have been interior fans and sidewall discharges. exterior system just freeze up with our ground soils moisture content and -20 days.
I freely admit i am a convert. Reluctantly only because i dislike swelling Rob's head about him being correct again.

I will freely admit i am a very strongly opposed (in first draft it was Hate) to one other practice that i am told continues to happen in the US. That their are a few (or many) mitigators in the US are still using SDR 35 pipe and that it is a practice that needs to be stopped. it is criminal to use a pipe that is not certified by the manufacturer to be used above ground to convey radiation laden air anywhere. in a country (US) that claims to be risk adverse for fear of legal damages how this practice survives I do not understand.
Gentleman and Ladies it is time to come indoors. Interior fans and sidewall discharge works.

I have been thinking that after we get past this virus issue in 2021 I am hoping we will have a a much more attentive audience in Government and in the public (a tiny little thing in the air that causes significant health risk in your home and workplace). Every body has some only way to know is to test and fix if high levels are found. i am sure much brighter minds than mine can come up with some really good ways to deliver an effective message that we could look at driving in the fall.

Good morning George: I would suggest that strongly that you consider from day 1 installing an active system in your new home from the beginning. Recent research here in Canada (CARST 2019) has shown that active radon systems (radon systems with a fan running continuously) save electricity, if the home is being air conditioned.
The entry of uncontrolled moisture from the soil through 70' of cracks or cold joints (that are less then 1/2 the thickness of a credit card) that the air conditioning system use a significant amount of electricity to condensate out. The cost of this electricity is 3 to 5 times the cost of electricity to operate a radon fan all year. Active radon systems not only control radon (when well installed and properly sized) but also control entry of many other unwanted soil gases, methane's, VOC's, old pesticides and also control humidity entry.
The other question that you asked is about the amount of radon that would be in your home based on EPA mapping. Please understand that radon levels are variable house to house year to year and hour to hour and can even change significantly with different occupants.i.e. my mother would not sleep in a bedroom without the window open, (cracked in winter but all the way open in summer while running A/C it drove my dad nuts). Today i would know that if that window was on leeward side of the house (it was) that her radon levels would be up, on windward side they would be lowered. In the 15 years i have been mitigating radon we have seen many neighbors have vastly different radon levels even in tract homes that were built by same builder same year.
Good luck with your new home!

As a radon mitigator i went out and bought a spray rig to be able to spray foam as a radon barrier for new construction. Spraying rubble walls over a geotext sheet is easily the best way to fix a rubblestone wall that may be emitting radon and if it is a lime mortar it is good for walls too, (lime mortar needs to keep moisture in it or it will sand out over time). Get the spray foam contractor to do joist pockets as well as this is usually a tough place to seal and can have huge energy savings, up to 15% of energy loss in modern construction occurs at joist headers.
2" thick Demilec soya 2lb spray foam is the minimum for radon that has been certified in Canada, I understand that BASF product line is in process of getting that certification as well but do not have it yet.
i would strongly support (if it were my client) that they consider a 3 or 4" thickness just from an energy savings perspective 2lb foams are about R-6 per inch

Yes, here in Canada we have an approval system for construction products that meet or exceed standards. this process is long and expensive. Demilec soya (not high lift) has received its CCMC # as a radon barrier. we have bought a spray-foam rig to service the new construction market for radon control.
Like all products in the radon world effectiveness is in the details and the competence of individual installer.
Most good sprayers are not of the small job temperament and they love to spray large quantities quickly.
so you will want to talk to several contractors. Spray-foam has some nasty chemicals while it is off gassing and owners and pets need to be out of house while it is being sprayed and for 24 hrs after completion.
I have been around construction in Canada a long time and have not seen a structural sandstone block wall could you share some pictures.
if this is what i am imagining, you may do well to provide something for the foam to hang on to as moisture and freeze/ thaw / movement of blocks may break bond of foam to blocks over time. I would ensure that the the spray foam does the rim joist cavities and spray foam in Canada must be covered with either drywall or another fire rated barrier.

Whoops chart did not translate to this format . what i was trying to show that if worker was exposed at 75 Bq/m3 or 2.0 pCi/l for 40 hrs week/ 2000 hrs per year they are at 1mSv dose under 2018 ICRP guidance.

Please let me clarify i agree wholeheartedly with communication testing. Dumping radiation into your workplace, is just people who lack knowledge of the risk they are exposing themselves to (that was nicer than just saying "STUPID" wasn't it?). Again I say Russian roulette with radiation. Radiation is not a cumulative risk it is a one instance where 6 things go wrong at same time and you have stage 4 lung cancer and you die.

if you own a company and you have employees make sure you clearly document work procedures to lower radon levels in workplace (introduce outdoor air and vent vacuum exhaust outside away from your outdoor air source) otherwise don't plan on leaving anything for your wife or kids, because your workers wife and kids will have it.

Bill as a Radiation Safety Officer and a mitigator I disagree with your premise wholeheartedly. I hesitate to say this out loud or worse write it down to someone who has been my go to reference for radon knowledge for over 10 years. I hope we can disagree on this without you taking offence. Radiation science continues to march forward on knowledge about the risk to humans and the ICRP has recently changed the risk that humans are exposed to from radon upwards by 2 1/2 times from 1993 knowledge.

Radiation protection mantra is "As Low As Reasonably Achievable" (ALARA). while you may be mitigating a home that is at 5.3 pCi/l or 200 Bq/m3 under slab radon is typically 10x to 100x the concentration in the home. These numbers are generated by many 100's of homes we have mitigated in Ontario Canada. Homes between 1x and 10x typically have large opening somewhere between the sub slab and the interior of home i.e. opening under tub or shower.

Dumping that level of radiation into your work space because you are trying to hurry to next job is Russian roulette with radiation. Either we are handsome radiation workers worth a bunch $$$ or a bunch of dumb ugly hicks who don't know better. I am hoping my wife sees me as the former.

In Canada from a radiation protection standard, workers are assumed to be exposed for a working day at highest level they are exposed to, unless they are actively tracking their exposure on a hourly basis.
Radiation protection NORM guidance is currently 200 Bq/m3 for Canadian workers for radon exposure based on ICRP 65 (1993), (currently under review).

current radiation protection limits say: (Canadian rules for sure and I believe USA rules as well)
Below 1 mSv dose ................. ALARA
1-5 mSv dose ................ track exposure, document and save for duration of worker life (25 years)
and lower dose ALARA
5-20 mSv dose................track exposure using approved dosimeter (very expensive in our world)
submit results to Government approved agency and lower dose ALARA

See below chart of exposures and how much they have changed since 1993. I apologize in advance for rounding errors.

workplace exposure 2000 hours
ICRP 65 (1993) ICRP Sydney 2015 ICRP 137 12.7 recommendations
Radon level Dose Dose Dose
Bq/mᵌ pCi/l
3000 81 8.69 mSv 45.39 mSv 40.05 mSv
1000 27 6.21 mSv 15.13 mSv 13.35 mSv
800 22 4.984 mSv 12.10 mSv 10.68 mSv
300 8.1 1.869 mSv 4.539 mSv 4.005 mSv
200 5.4 1.246 mSv 3.026 mSv 2.670 mSv
150 4.0 0.934 mSv 2.269 mSv 2.002 mSv
100 2.7 0.623 mSv 1.513 mSv 1.335 mSv
75 2 0.467 mSv 1.134 mSv 1.001 mSv
60 1.6 0.373 mSv 0.907 mSv 0.801 mSv
50 1.35 0.311 mSv 0.756 mSv 0.667 mSv
40 1.0 0.534 mSv

Necessity is the mother of invention....... what was the pressure field extension? i hate yellow jackets every time i get close to a nest i get bit WAY TO GO BILL !!!!

Radioactive mutations is likely how we got to be here! i like being at the apex of the food chain! thank you ancestors. :-)

Sorry i was unclear , the"it" was radon diffusing into the plants and soils........ What i was trying to say was the introduction of plants and soils into a volume of air that has a known activity (baseline). the plants offer now a smaller volume of air in the chamber when the radon adsorbs by diffusion into houseplants could change significantly the measurable alphas in the air from radon and daughter products until stable levels are achieved (the plants and soils now have a radon concentration of close to 5200 Bq/m3) . After stability is achieved it is also possible that the alphas created by radon and daughter products would not likely leave the plants and soils to be able to be measured, and what appears to be plants reducing radon could be pillows reducing radon.

The reduction could be simply achieved by the plate out factor, of a much larger surface area, created by the plants in the chamber. If one was only determining the levels in the chamber from alpha strikes, thereby inferring radon reduction but not really achieving it..... i still don't think this would stand up to field testing. i do hope someone got a PHD out of this, but i have trouble believing this. (that's Plumbing, Heating and Drains) which is the only one i have...........Bob the plumber

So if i read this research paper correctly in a chamber over 72 hrs the plants reduced radon levels faster than test decay rates. i did not follow the math see by how much. i also did not see how they were measuring the radon levels based on gamma emmisions or alpha emmisions. Some adsorbtion into anything of volume in a chamber would reduce ability to measure the actual radon in the chamber by reducing the measurable alpha because alpha would not get out of plant or soil once it diffused in.
i am very suspect of this science could stand up to actual field testing. likely the belief that put forward by "plant lady" is just another well meaning non scientist spouting radon facts based on partial understanding of radiation science...... just like radon is a big heavy atom so it sinks to bottom of house claim i have heard over and over please if you are in the business squish this radon myth any time you can.

Oops i meant untrained uncertified

Looks like untrained certified read some stuff on internet, Billy BF with a truck kind a mitigator, they are learning, I see a transfer from sheet metal to PVC, no manometer no labels, probably no insurance, but at $749.00 very difficult to be sustainable as a business, in USA courts will take them out sooner or later.

Interesting that you would only test 10% in a school, that is usually the number of rooms we find high in a commercial building/school our guidance in Canada is to test 100% of ground contact rooms with 3 month tests, then review high test for occupied hrs. (definition of occupied is sometimes challenging) .......