There are several ways to help with the proper ventilation. You can install ridge vents which are continuous running vents along the ridges or peaks of the roof that are then capped of with roofing shingles so they look good and give you added ventilation. A few inches of the roof sheathing is cut back from the peak on each side to allow for the proper ventilation.
Gable vents are also a great addition to help with the flow of air in the attic that will help keep things cooler. You can also add thermostatic controlled gable vent fans that are set to come on at a predetermined temperature.
Also, make sure that you have vented overhangs. If the overhangs are covered with aluminum, you can get the material vented and install one vented piece for every two non-vented pieces. We have also installed all vented pieces to really help with the air flow in problem houses. If you have wood overhangs then you can have vents installed in the wood.
Roof vents can be placed on the back side of the house where they are less apt to been seen and these help a lot also. There are also some great roof ventilators that can be used.
One such ventilator is called the Aura Ventilator which acts like a turbine to remove heat from the attic. There are also solar powered ventilators like Aura Solar Powered Roof Fan which is powered by the sun and can provide huge energy savings.
Now that we have that out of the way, let’s talk about roofing material. First of all, the lighter the color of the roof the better it will be at reflecting the heat. Trust me, dark colored roofing really holds the heat and thus your air conditioner will run longer then with a lighter colored material.
The Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, and the Florida Solar Energy Center have put together a chart that shows the best roofing materials for Solar Reflectance and Roof Temperature.
Remember keeping the roof well ventilated and the roof cool will also help with the dampness issues and save you energy as well.