What is the minimum space required between the insulation and the roof sheathing?

The minimum space required between the insulation and the roof sheathing is essential for maintaining proper ventilation and preventing moisture buildup in attics. A one-inch gap allows for adequate airflow, which is critical in reducing the risk of condensation that can lead to mold and rot within the roofing structure.

Having this space is a requirement based on building codes and best practices in construction, as it ensures that the insulation can perform effectively without creating a barrier that traps heat and moisture against the sheathing. This gap helps create a "ventilated attic," supporting temperature regulation and improving energy efficiency in residential buildings.

This specific requirement is grounded in the need to balance the thermal envelope with sufficient ventilation, ensuring that homes remain comfortable and structurally sound over time.