I do not know your situation, but it is hard for me to envision how a door cannot be protected. Every door I have seen has a flat permieter, so the sensor can be mounted on the door. And if the casing will not accomodate that little tiny slim magnet is some fashion (mounted straight, sideways, on the jamb protruding into the door area and move the sensor over) that would be really unusual. And I would think the same with windows. But . . . I am not there and have not seen. Just thinking if that will not work, hard to envision how any sensor & magnet will.