R806.2

Section R806.2 is titled 'Minimum vent area' and covers the requirements for providing adequately sized openings to allow for air circulation within attic and rafter spaces. The ratio of the minimum net clear ventilation relative to the area being ventilated is established. The purpose of this section is to prevent excessive mold growth, moisture collection inside the building, and premature degradation of framing members. This section has an exception which allows for a reduction of the ratio in certain geographical locations, where the ventilation is done in a specific arrangement. The purpose for the exception is to allow for lesser ventilation where the risks of moisture accumulation are reduced.

The model shows a partial roof section with the attic area highlighted as well as the soffit and mushroom vent areas highlighted which must be 1/150 of the attic area (presuming the building is not in climate zones 6, 7, or 8).