What is the required clearance between the bottom of the roof sheathing and the insulation for a cornice vent?

The required clearance between the bottom of the roof sheathing and the insulation for a cornice vent is important for ensuring proper ventilation in the attic space. A clearance of 1 inch is specified to allow for adequate airflow and to prevent insulation from blocking the venting system. This clearance facilitates a constant movement of air, which helps to manage moisture and temperature within the attic, thus reducing the risk of mold growth and maintaining the overall integrity of the roof structure.

Having a minimum clearance also aligns with building codes and best practices in construction to ensure that the airflow can help evenly distribute temperature and reduce the likelihood of condensation forming within the insulation or on the underside of the roof sheathing. Ensuring that this space is maintained prevents issues that could arise from inadequate ventilation, such as ice damming or premature roofing material deterioration.

In this context, a clearance of 1 inch is not only a requirement but also a practical measure for effective attic ventilation strategies.