Why is it necessary to have laps at the joints of rolled roofing?

Having laps at the joints of rolled roofing is essential primarily to prevent leaks. When installing rolled roofing, the overlapping sections create a barrier that minimizes the chances of water penetrating the seams. Water is known to find its way into even the smallest gaps, and without proper laps, these joints could be vulnerable points that lead to leaks. The overlaps ensure that water flows over the edges rather than seeping underneath, effectively directing it away from the structure.

While proper drainage is important in roofing systems, the main purpose of the laps is to enhance the watertightness of the installation. Aesthetic value is not a primary concern in roofing applications where functionality is critical, and additional insulation is not a factor directly influenced by the laps in roofing material. Thus, ensuring that laps are correctly made is a crucial component of rolled roofing installation to maintain the integrity of the roof structure.