Soffit vents are pretty much standard on all homes in Canada, as with gas code, the minimum clearance for a furnace is 3 feet from a soffit vent, however the rim joint is the top of basement foundation wall, where the main floor , floor joists sit and are banded, with “rim joist”
You can’t get much further away from a soffit. 10-20feet.

Here is the conclusion

I will reach out to Health Canada, to find the dispersion testing they did on one of my 20,000 Bqm3 homes, it was really great.

Since Bob Wood, seems to be sleeping.
I have over 3000 Canadian Radon systems, no reintrainment and every home gets a AIR THINGS monitor, just as a we have smoke and Carbon Monoxide detectors.
Today’s fans don’t leak, so long as you stick to the big 3
PVC pipe, is highly robust and it has proven the test of time, with millions of HE furnace installations- leaks = death, literally!
So we have chosen to eliminate the major failure that -40 deg temps, impose on a Radon system-using indoor fans.
But 0 failures in 14years.

Good presentation, 1 thing, vent your vacuum outside.
You can buy PFE test rigs from Radonmatters

That first one is scary, for sure- Being Canadian and actually do specialize in indoor installations, aside from fan sizes, 99% of our systems look the same- they seem to use, whatever is on the truck. Nothing “standard “ - but that’s what you get for $749.00
Is Colorado not a regulated state?

I remember the first membrane my partner installed, I had left him alone, to do the work, on the last day, I got a panic call from, him, saying the membrane is rising off the floor- what do I do- I laughed and said: Perfect, means your seal is perfect- plug in the fan.
By the time, I got off the phone, the membrane was tight to the ground.
Maybe not a direct answer to your question, but it’s all about air pressure and which one, is stronger.
We never leave poly exposed, we only use Fire/ smoke rated products.

We use the system 600, available at Lowe’s, there are a number of commercially available products, that have been tested in our Radon Chamber such as Demilec Inc.

Concrete must be clean, no matter what you use, but we now use 2lbs spray foam exclusively.
2 coats 1” -tough as anything once cured.
3-4” on concrete and the same on membrane edges

Well Terry, I have over 3000 systems, with fans in the basement and rim discharges and every one, is below 100Bq m3 or 2.7
Some were as high as 20k
So if that helps, stir the thoughts.
One note, stick with the big 3, there is a fan, out there, from another manufacturer, that does leak!!

I personally don’t have much trust in any fan, aside from the big 3, all of which, were tested by our Canadian National Research Council for leakage- especially important in Canada, where our fans, go inside- nothing survives-40 degs!
Stop looking for cheaper alternatives is my word of advice.

Schedule 20 pipe or actually SDR35 thin wall pipe, is designed for sub grade or continuously supported and is stamped right on it- for use below grade only- that said: it is extremely brittle in cold temperatures and cracks very easily- these cracks occur laterally and can go undetected.
Go to a plumbing wholesaler and purchase sch 40 or 4” 636 vent pipe-I have cut out dozens of thin wall systems and will continue to flag them- repeated offences, could lead to certification suspension.

I will try and dig up our Health Canada survey of 100 homes, that 3 of our Canadian Mitigation contractors installed, we all target less than 2.7 or 100bq/m3-

Membranes, are much cheaper- however there are many benefits to spray foam.
https://www.demilec.ca/documents/Radon-Brochure-English.pdf
Our research council, tested their products in their radon barrier testing facility and it was found to be excellent.

We have done 2 to date and both luckily had a moisture barrier under them, so we verified it’s integrity by reading communication under poly and building pressure simultaneously- in both cases we were again lucky and ended up moving +/- 80cfm at 1” WC - btw- 6” hole in floor, is much easier to get your hands into-to seal your suction pipe to poly- we just blue skinned it in place and slipped a flange onto floor for stability.

New regs in Scotland seem to mimic ICRP guidelines so I think it’s a matter of time, to see levels, below 100bqm3 or 2.7 in every country

Never seen a leak on any of 2000 plus indoor fan systems! Plumbers don’t have leaks, why would a radon mitigator?

What about RIBITS facility at NRC in Ottawa?

Now, that would be great!

I have to agree with Bob 100%, anything to get the word out, but with 50% or more variations in readings- for various climatic and home use reasons-it could provide a false sense of security.
So long as all information is provided with loan program- and they actually read it. I feel, they should do, more good than harm.
But the question still remains- will they be motivated enough to mitigate?