Crawl Space walls and Rims joist

When I audit double wide home there are walls of the crawl space and rim joist that need to be treated and usually with spray foam.  I can’t seem to figure out how to have the walls of the crwal space and the rim joist be modeled seperately.  The doesn’t seem to be any wall in the crawl space and just the rim joist is not enough money so i have to over ride and do the input of the cost of the measure.  Is there a better way?