What allows a roof to leak air but not water?

The correct answer involves the design and function of air barriers in roofing systems. Properly shingled termination between air barriers creates a configuration where air can pass through while still effectively managing moisture. This technique ensures that the interfaces of air barriers are layered in a way that allows for ventilation and air movement, yet prevents water intrusion.

When roofing systems are correctly designed with overlapping materials and sufficient slope, the water is directed away from sensitive areas, while air pressure differences can still allow for air leakage. This characteristic is vital in maintaining the integrity of the building envelope, ensuring that air quality and energy efficiency are maintained without compromising the waterproofing of the surface.

Other options highlight issues that would generally lead to problems in roofing systems. Holes in the roofing membrane would allow both air and water to penetrate, creating a serious breach in the system. Improper flashing can create pathways for water to enter and compromise air barriers. Closed windows during rain do not relate to the air-water barrier relationship in roofing but rather pertain to the management of air pressure and moisture within the building's interior environment. By understanding this, it becomes clear how proper termination techniques are essential in achieving the desired balance of air permeability and water resistance.