Roof vents prolong the life of a roofing system by reducing moisture within the system. Two-way roof vents a.k.a. Breather vents not only release moisture, they also reduce air pressure. They are designed specifically designed to eliminate negative air pressure, promote air flow eliminating any moisture / condensation between flat roof areas. The vent has cap to prevent water and snow getting in and it attaches to the roofing membrane thus making it watertight. It is recommended that there should be one vent for every 1000 sq. feet of deck area.