Heavy rain. When a tropical system or a stalled storm sits over the area, rainfall totals climb fast, and the flat terrain across this part of Harris County drains slowly. A flat commercial roof has to move that water off quickly, and when drainage falls behind, the ponding and leaks follow. On a corridor this built up, the runoff has to compete with everything else draining around it.
Heat and UV. Long Gulf Coast summers push membrane surface temperatures far above the air temperature for months at a stretch. UV degrades the membrane, dries asphalt-based systems, and stresses the adhesives and seams. Heat is the steady force aging every flat roof in Webster whether or not a storm ever arrives. Why drainage is the real issue on these roofs



