Why should Metal Valley flashings be no longer than 10 feet?

Metal Valley flashings should be no longer than 10 feet primarily due to the effects of thermal expansion and contraction. As temperatures fluctuate, metals expand when heated and contract when cooled. If the flashings are too long, this movement can lead to buckling, warping, or other forms of deformation, which compromises the integrity of the roofing system. Properly managing the length of these flashings ensures that they can accommodate natural thermal movements without compromising their function, which is to redirect water away from the valleys and prevent leaks. This consideration is critical for maintaining the performance and longevity of the roofing system.