When is a head lap particularly important in roofing?

Head lap is particularly important in roofing systems, especially in steep-slope roofing. It refers to the overlap of shingles or other roofing materials at the top edge of the course below, which is critical to ensure that water sheds effectively off the roof surface.

In steep-slope roofing, where the incline is significant, the potential for water infiltration through gaps or overlaps is greater. The head lap helps create a water-tight seal by ensuring that water flows over the overlaps rather than seeping in. This is key in preventing leaks, protecting the underlying structure, and prolonging the lifespan of the roof.

While head lap is also relevant in low-slope roofing applications, its critical function and impact are more pronounced in steep-slope systems where gravity plays a more substantial role in the movement of water across the roofing surface.