 You hope you can get one contractor for both, but maybe you have to get a roofer for the ventilation, and then maybe you have to get an insulating company to insulate the attic if you need it. You may not need the insulation part. And I think you do, though, because in California, because it's not really cold, they don't do a lot of insulating, which is weird because you need insulating for air, too.