While i agree with Rob on many things, I have one very cautionary note: Us northern cousins in the mitigation field are (currently) very heavily weighted to existing tradesman, that changes methodology as does the new focus of training and exam to communication testing/fan selection.

Trades and something that nobody else knows how to do (communication testing/fan selection) adds value to what we do. Trades are seldom hesitant to charge for their time /knowledge and ability to stay in business. That is one of the reasons we have been able to hold pricing at a significantly higher level than our US cousins.

Indoor fans without quality of workmanship/materials is a significant risk in the radiation world.

Plese add: with rooms above

Doug others on this list may be more expert at what makes a fan, a "radon fan". Here in Canada we struggled with the same thing, In writing our mitigation standard for existing buildings we ended up striking a secondary working group around this issue ( it was the big three of radon fan manufacturers). I believe that the criteria they came up with was:
1/ it was designated by fan manufacturer as a radon fan (not some sales team but the fan manufacturer)
2/ fan had less than ???? 2% leakage
3/ fan was made of a material that was not subject to breakdown

Garages with overhead rooms above are a tricky subject when it comes to air sealing (very subject to individual trade or tradesman quality of work) and that may be why EPA and AARST have said that fans are not to be located in garages.

I would not use polyurethane unless i had checked with manufacturer that they adhere well to poly products, a quick conversation with rep will go a very long way to sucess. we use dow corning construction sealant, low VOC, Cheaper than polyurethane I was buying before, comes in sausage tube, so i can use my battery operated gun. Ships direct to office when buying case quantity.
I would not adhere with just caulk we use a backer bar that is nailed into wall with Hilti nailer squishing caulk to wall and to poly.

Good morning and Happy New Year from frigid Canada: I was having a discussion with my Dow corning sales rep and he challenged me to do some tear apart tests with his products and the caulking products that i was using. i was discussing low VOC products with him at the time. Caulk things together wood, brick, concrete, PVC to concrete, vapour barrier to vapour barrier Etc. and let sit for 30 and 60 days and then try to tear apart.
Well it became the best sales tool that he could have used. I was amazed to see that my go to poly urethane caulk literally fell out from between two pieces of 15 mil poly at 60 days, thank god we had always taped our seams as well as caulk.

I am now a die hard fan of low VOC silicone because I KNOW IT WORKS and it is cheaper (when i buy in bulk) it is also in sausage format so i have another tool that my handy homeowner does not have that's why he is paying me to do it. I recommend that you always go up a step and talk to manufacturers when you can (they do all this research) what works where and where not.

Interesting that you mention garage practices, in Canada I have been corrected many times by designers and code officials that a fire collar is not required by our building code as a garage wall is not considered a fire seperation bbut is considered a smoke seperation (we still install fire collars).

This has been a long time coming. Thanks to the committee members for all of their hard work and time away from their families and workplaces congratulation to the team!
Committee Co-Chair
Bob Wood

While I understand the employer not wanting his people certified as they may branch out on their own. May cost employer more etc. It is a two day course. I feel as an employer I want all my staff to be certified, including the office because it gives my staff the ability to create the knowledge base that allows them to create relationships with us being experts for our customers.

Schedule 20 does exist in theory the manufactures could make it in 4" they just don't have a market for it. The US Mitigators saw SDR 35 as an inexpensive alternative in highly competitive markets without realizing that it was not rated by manufacturer for above ground use. I would not want to be in those shoes in a highly litigious society that they work in.

Shawn i think that the lack of people moving forward into mitigation is the industries fault .... no i really mean this. We have allowed Government driven testing programs to drive Risk communication wording and it is their bias to choose wording that is normative to be non- threatening.
Risk communication really really depends on the words we use to communicate it is not good enough to communicate using the stuff we understand we need to give the recipient of those words an understanding of what we are trying to say.
if we use new words like "radon in your home is naturally occurring". They don't know what radon means we do, But the general public will skip over and ignore terminology that they do not understand (we have been trained to do this since we were taught to read) and have a bias in their listening skills that their castle ( their castle is great; after all they pay for it every month). If we were to change that statement to "the radiation caused by radon in your home comes from the ground around and under it." You get rid of a word "natural" the normative belief is that everything that is natural is good for you is the bias thinking. insert the word "radiation" radiation is normative belief is radiation is bad for you. just changing around some the terminology significantly changes peoples reaction and understanding to what we are saying.

I think that requiring a real estate transaction radon test would save more lives. Possibly it would increase my business, it has been my belief that a radon requirement during a real estate test would drive many people into the industry and drive down prices and significantly affecting my profit margins negatively. It would likely take my sales up but overall profit would remain about the same. It would however smooth out my yearly sales a bit and soften some of the business cycles.
CARST is in the final stages of a real-estate guidance that may be uptaken by Goverment that involves a short term sample during conditions period with moneys going into escrow if a sample result comes back above a much lowered guidance level. A long term test once new owners are in and mitigation will proceed with sellers money if radon test comes back above an agreed upon level(Heath Canadas guidance?) This system if adopted will preserve Health Canada's long term test focus, preserve real estate commissions for realtors (so they can get on board) , most of all it will protect many more home buyers and cost the government nothing, a byproduct is that it may raise radon awareness significantly.

One thing about the Canadian industry is that we continue to loose good people (mitigators and testors) who are unable to continue in the business for lack of work. My service area spans 10 hours of drive time with approx 10 million homes and we are fortunate to do 150 miigations a year. Without my VOC work and some new construction projects we would not be able to stay in business. We just celebrated 10 years in business and I finally gave up my day job.

One thing that many people don't know about rubble-stone walls is that the mortar that holds them together is not concrete based but is a lime based mortar, these lime based mortars require moisture to keep from sanding out in essence they breathe the moisture in and out. They were not designed to be finished on the inside. Finishing over lime mortar with concrete will result in the mortar sanding out in the interior of wall which will in all likelihood cause a structural failure over time (may take 50 years). In designing a system to weatherize a rubble-stone wall you would need to keep this in mind.

I would suggest something that was done on a historic building rebuild that i was involved with: where the architect had us mechanically fasten dimple-board on interior of the rubble wall and then seal the outside of the dimple-board with a medium density foam 2" thick (like Demilec "Soya" ) to below the concrete floor for a R-12 insulation, air barrier, vapour barrier and radon barrier, and a drainage plane to sub-slab gravel then use open cell spray foam or batt insulation to achieve required insulative requirements. By following this procedure you will allow rubble-stone wall to still breath in moisture and not likely harm the ability of the lime mortar to continue to breath in and pass around moisture.
Don't forget to spray foam and insulate the joist headers, as these i understand can be up to 12% of the energy loss on a modern building.

As Bruce said above do not forget that spray foam must be installed by certified contractors and that Isocyanates are a chemical sensitiser, and as Jay above said spray a coat of fire retardant if they are to be left exposed (not behind drywall)

Bob Wood

Wow! What a great piece on radon. It is amazing and very powerful when a news organisation gets it all correct! congrats to all who were part of this.

Good morning: we also use the lexan method we buy it from a sheet supplier and get them to cut it into 2' X 4' sheets for us so it easily fits onto truck and reduces cost significantly from buying from big box stores. One of my guys was having trouble sourcing lexan locally and has gone to checker plate aluminium does it ever look sharp!

Jim we will miss you i still talk to my customers about the radon chambers that we built in Vegas in fact we now have a 24 x 18 inch one that we take out to home shows etc what you taught me was you can talk radiation till you are blue in face but when people can see it they now get what you are talking about.
its about communication and that is what you were always so good at. Thanks for teaching me! have a great retirement and I hope you still come out now and again!

We have done a number of these buildings. As the floor vapour barrier was not in good shape we had to install a new vapour barrier on top of existing floor (pt plywood) , we removed base board and tied into wall vapour barrier and installed a new plywood floor over top of. Our communication testing allowed us to use a small fan and these buildings communicated right up the walls. Significant radon reductions from 1200 -1800 Bq/m3 down to less than 20 Bq/m3.

Larainne I am suggesting that we (as North American mitigators) have a dilemma we have one standard in US and a very different standard in Canada. Your way works really well (post testing in real estate transactions) show this and Canadian (post testing for concerned home owners) show this. Post testing is part of what we are required to do as a mitigator. Having two significantly different ways of pipe routing for mitigating is confusing for non educated clients. While i was initially a staunch supporter of EPA style systems, I must produce a product that does not cause my clients significant grief during the winter months. I often wonder if research was re-conducted if these issues would reemerge. Radon at 5.3 pCi/l is 4 parts / quadrillion or 4 parts X 10 ⁻¹⁵ it does not take a lot of air mixing to diffuse that back to background.

I am not sure how that is happened during EPA House evaluation as we in Canada have installed 10,000's of systems using band joist or rim joist discharges with houses passing both short term and long term follow-up testing. I agree that the US EPA style systems are inherently safer as they have no pressurized piping within the building envelope, this allows for many installers to have little or no construction, pi[ping or building envelope experience to effectively mitigate homes in moderate climates. Most dispersion studies i have read show dispersion effectively back to background within 3-4 feet even within the plume path so it baffles me how reintrainment (even with very high levels, how this could have happened during EPA home tests. Radon is a science and a sometimes and maybe world.
Here in Canada we do have some extremely cold spells and up the side of the home or up through the roof systems with low- moderate flow just freeze up solid doing our clients no good at all, I never though i would say this, side wall discharge and fans indoors just works better in our climate.

Did you try sucking on the block wall, had one a while ago could not get it despite slab being all under negative pressure. Grab sampled in the block and found 100 pCi/l in wall. Sucked on block all 4 sides down under 2