What is spaced sheathing primarily used for?

Spaced sheathing is primarily used for ventilation under wood shingles, which is crucial in roofing applications. The design of spaced sheathing involves creating gaps or spaces between the boards, allowing for air circulation. This airflow plays a significant role in preventing moisture buildup, which can lead to wood rot, mold, and damage to the shingles themselves. Proper ventilation is essential in maintaining the longevity and effectiveness of a wood shingle roof, as it helps to regulate temperature and moisture levels.

While the other options present potential functions of roofing materials, they do not align with the primary purpose of spaced sheathing. For instance, providing a solid base for tile roofing is not applicable since spaced sheathing is not designed to support heavy roofing materials like tiles. Similarly, while adding weight could theoretically stabilize a roof, it is not the primary intent of spaced sheathing. Lastly, improving insulation is typically associated with different types of materials and methods, rather than with the primary function of facilitating ventilation, which is the core purpose of spaced sheathing.