Hi Doug

Several Canadian regions have had this in place for a while. The city of Guelph in Ontario where I live was one of the first to introduced it about 7 or 8 years ago for their new builds in order to comply with provincial building code requirements. There was some builder push back and confusion at first but it runs like clockwork now. Even before that there were provisions for this in a supplemental building code (SB9) for a few mining regions in Ontario.

Bruce:
Thanks for the input. I just looked at the City of Guelph's website and it read as though the mandatory measurement was only required when Option#1 (a Rough in System) was used but not required if Option 2 (soil gas barrier on walls and slab or Option #3 (soil gas barrier on walls and an active system)

Bruce and Doug: Hi my old friends! Their are now over 15 municipalities in Ontario that are or have implemented a version of the Guelph interpretation of Ontario Building Code. They are even requiring large commercial builds HVAC engineers to state how they are preventing Radon from entering the building.It is resulting in at least developers are reaching out to radon mitigation companies for quotes. Not nirvana but it is a positive change.

Doug. You are correct. That is a fault simply because of what is in older building code. The City can't legally enforce more than what is in code. There is also a slightly different stream for ICI buildings where post mitigation testing is completed. That being said, myself and every consultant I know in the area wraps in post mitigation testing for residential and commercial. Here in Ontario the new home warranty makes the builder liable for high radon so they want the testing done.

Thanks, Bruce and Bob: So, practice is exceeding code at least in larger buildings (I assume ICI is Industrial, Commercial and Institutional buildings, Correct?).

OK, we have heard from Canada. I ask the question again for our US based contractors: Is anyone aware of any jurisdiction that has adopted Appendix AF of the 2021 IRC?

Huh. I didn't realize it was Appendix AF now. For six years I've referred to it as Appendix F. I guess this is new with the 2021 version of the IRC?

As to the original question, there are a handful of municipalities in PA that adopted Appendix F. Maybe around 15 in the whole state. And they adopted it years ago. That's about it as far as I know.

I don't know if any of them updated to Appendix AF.

edit: I guess there were 18 municipalities that adopted Appendix F, last I checked one of them was working to remove that ordinance. Some of those municipalities hadn't seen any new homes built the year that I asked. One of them claimed they're pretty much "built out" already, I guess that means not much room left to build anywhere.

This post is 9 months old, but does anyone know of a list of all municipalities which have adopted Appendix F or AF? There is an old EPA Radon web site that is still available that has a pull down list by state (https://19january2017snapshot.epa.gov/radon/building-codes-radon-resistant-new-construction-rrnc_.html), but I am looking for all cities in a single list. We are attempting to get Appendix F of the IRC adopted by the City of South Lake Tahoe, CA. Based on the above info I will look into Appendix AF of the 2021 IRC as well.

I did not get any response to my previous post so I took the old EPA pull-down data state by state and built it into an Excel spreadsheet. It turns out there are 154 cities and counties and 30 states which have added RRNC Appendix F regulations to their building codes, at least as of 2017. It would be great if the EPA kept an up-to-date list of cities that have adopted Appendix F and AF.

If anyone would like a copy of the spreadsheet, it is available on my website: http://radonattahoe.com/present.htm

Thanks, Jeff, for your contribution. I hadn't been following Doug's thread. I wasn't aware that EPA had such a list that was a reasonable attempt at being comprehensive, even if it's not necessarily updated.
Much better than my own rough answer (given in a separate thread).