What is the minimum free opening required between sheathing and insulation in an insulated sloped ceiling?

The minimum free opening required between sheathing and insulation in an insulated sloped ceiling is 1 1/2 inches. This space is crucial because it allows for proper ventilation and air circulation, which helps to prevent moisture buildup in the insulation and roofing materials. Adequate airflow is needed to manage humidity and reduce the risk of mold and structural damage.

In Virginia, building codes emphasize the importance of maintaining this minimum distance to ensure that insulation does not block vents or impede airflow. This gap also plays a critical role in maintaining energy efficiency by ensuring that the attic space remains appropriately ventilated, which can help in regulating temperature and reducing heating or cooling costs.