In Martin Holladay’s article on creating sealed crawlspaces, he seems to recommend rigid foam or spray foam over the vapor barrier that extends up the crawl space walls.

I’m unable to get sheet material into my crawlspace, but I have doubts that the spray foam would adhere to the poly vapor barrier. 

Google searches turn up contradictory statements along with a large chunk of “check with the manufacturer.”

Does anyone have advice or experience with this? Does spray foam stick to poly? Thanks for the help!