If I were going to do this, I would measure the opening of the existing vent, then go to Lowes, ACE, or Home Depot (or online) for a Gable fan of around the same size, large enough so the screw mounting holes will be outside the existing hole. These typically mount with 4 screws one in each corner. The sheathing is typically 5/8 so 5/8 inch screws would not penetrate the shingles or under layment. I would also install a thermostat to control the fans.
__________________
Pennsylvania, for 60+ years, most recently, Allentown, now TV. 
|