My first-floor half bath vents into the crawlspace, which violates the code, and I would like to correct it. A feasible way is to extend the hose from the current vent in the crawlspace to the nearest wall, and to cut an opening there. However, the wall in the crawlspace is concrete with rim joist sitting on it, and both are difficult to cut, and may affect the strength of the structure. I want to use the existing vent opening in the wall, is it feasible? Is it easy to remove the vent? Is there any adapter as the opening is a rectangle?