Notice the roof is a huge piece of wood. With metal bars on top. Zinc coating on the metal. A great choice to boost longevity. Metal beams with zinc on top of wooden beams. Not paint !!! It deals amazing with humidity.
Preserves metal against rust. In that zone dew point could form quite often. The membrane on top won’t be in direct contact with wood. Highly recommend to char the beams. Burn them with fire. Way cheaper than paint and it will last a lot. Bugs will avoid it.
Note the huge wooden beams. Half of it is filled with insulation. And the other is for airflow. (under the roof membrane).
This airflow will “counter fight” dew point. The air will be almost always hotter under the membrane than in the outside air. That means it will take up all of the humidity from the air. It will dry out anything. Check out the sections again.
Wood’s death is water. The metal bar “insulates” the wooden beams from the rooftop. We need a few membranes right on the insulation. These membranes won’t let water droplets penetrate into the structure in case they fall down from the roof membrane).
These membranes (positioned right on the insulation) will let water vapors evaporate. Constant airflow will take care of it. The roof will be bone dry.
Notice in the summer sun the insulation itself is shaded. The hot air will leave the structure easily. No air conditioning needed.