I'm going to re-roof my house and several of you recently helped me on my question about shingle brands. Very useful and I appreciate your help. I now have questions on ridge vents. Three of four contractors would use GAF Cobra. One would use an "elevated" or ridge vent that is higher than Cobra. I think it would be Owens Cornings VentSure. He says this allows hot air to roll out of the attic, whereas Cobra doesn't have the same flow or pull. I do wonder how hot air escapes through a ridge vent, given that hot air rises and so seems to me would accumulate at the top of the attic and sit there. What's the skinny on ridge vents and what do you in the business recommend? Also, what about hot air accumulating at the top of the attic? Thanks for any information.