My original roof lasted 26 years. It is 11 squares in size. Back then, they used felt underlayment which as you know is breathable. With the felt underlayment, they only had 4 turtle vents (that is Louver vents).
The question is: when I get my roof replaced now, they are going to install synthetic non breathable underlayment. In that case, will the four turtle / Louver vents provide enough attic ventilation ? Or, do you think that we will need to increase the amount of vents.
If you think that 4 louver (turtle) vents will not be enough, can you please suggest what type of vents and how many, if applicable, would be appropriate with the non breathable underlayment in the case of my roof ?
Should I add ridge vents to the turtle vents ? Or replace Turtle vents with ridge vent ? Or simply increase the number of turtle vents, and if so then how many ? What do I need to do to compensate for replacing the felt with synthetic non-repeatable underlayment ?