What is the minimum space that should be maintained between insulation and the roof deck sheathing?

The minimum space that should be maintained between insulation and the roof deck sheathing is essential for allowing adequate ventilation, which helps prevent moisture buildup and potential damage to the roof structure. A space of 1 inch is generally recommended to ensure that air can circulate properly and minimize the risk of condensation forming within the insulation or on the roof deck. This circulation can help maintain consistent temperatures and reduce the chances of ice dams forming during colder months, which can lead to water infiltration and damage.

A larger space than 1 inch is not typically required for effective ventilation, and while greater clearances can still contribute to airflow, the key focus is maintaining that minimum gap to support functional ventilation.