Another thing I am rethinking is the piping that the radon mitigation calls for under the vapor barrier.
I stuck a pipe under the vinyl, measuring for connection to the vent pipe and it looked kind of ridiculous. A short piece of pipe there close to the vent is not going to pull much in the way of radon laden air from under the sealed vapor barrier into the vent. And it would block the vent from pulling air from the entire crawlspace.
If radon gas does escape from under the vapor barrier, then the fan should pull it out of the crawlspace before it got a chance to make its way through the insulation and flooring. I’m going to take out this pipe to the vent and just allow the fan to draw air from the entire crawlspace. This matches the crawlspace conditioning requirement that household air is drawn through the crawlspace area instead of outside air. I’ll put a vent to the crawlspace in the master bedroom so that there is an intake. The stairs also have some cracks that would allow house air to be drawn into the negatively pressured (due to the fan) crawlspace.
Just waiting for delivery of more R-7 pipe insulation and the crawlspace area will be complete–until we decide to add extra insulation to the unburied walls.