Not only do they get in the way for a semi flexible solar panel, obstruct the wind flow for an aerodynamically favorable roof, They leak. We install internal fans and have screens on our doors. We also have a pass through screen between the bedroom and kitchen, and best of all we don't put a big hole in the roof for a fantastic fan. Last thing I want over my head on a major rain storm, is a leak. Want more proof ? Check out the following links: http://www.rvitch.com/forum/index.php?topic=61849.0 http://www.popupportal.com/threads/darn-vent-leaks.85559/ http://www.casitaclub.com/forums/topic/13338-leak-at-fantastic-fan-on-roof/ https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23517866/print/true.cfm I could go on, but I think you get the point...
