What is the purpose of the head lap in shingle installation?

The head lap in shingle installation serves the critical purpose of protecting against wind uplift. This is achieved by ensuring that each shingle overlaps the one below it sufficiently, which minimizes the likelihood of wind getting underneath the shingles and lifting them off the roof. When shingles are properly installed with the correct amount of head lap, they create a more secure and waterproof barrier.

Having the right head lap is essential for maintaining the integrity of the roofing system during heavy winds and storms, thereby increasing the durability and lifespan of the roof. Although other factors, such as drainage and compliance with building codes, are important in shingle installation, the primary function of the head lap is focused on preventing wind damage.