What should be done with the first course of shingles before installing subsequent courses?

Starting with a full strip for the first course of shingles is crucial for ensuring a solid and reliable roofing system. The first course acts as the foundation for all the subsequent courses, and using a full strip helps to establish a uniform and consistent layer. This not only contributes to the aesthetic appeal of the roof but also aids in proper water shedding.

Using a full strip ensures that the overlaps and alignment of the shingles above are optimal, which helps to prevent leaks and water ingress. It also allows for proper nailing patterns to be established, holding the shingles securely in place against wind and other environmental factors.

In contrast, other methods mentioned, such as leaving gaps for drainage or overlapping by 6 inches, could create potential weaknesses in the roofing system, leading to issues with water management or structural integrity. Additionally, proceeding without installation ignores the necessity of laying the shingles altogether, which could compromise the entire roofing project.