We are having our roof replaced and want to add a roof vent for our current bathroom vent that is just a vent hole above the shower that is terminated into the attic. There is no power. In the future we want to add a bathroom power vent, but for now we need it to go to the roof and vent out without pressure. Also want to prevent birds and rodents from entering. Please suggest a good roof vent that will be installed with new roofing, not leak, prevent rodents, and allow air to vent out without pressure.