Plastic dries out quickly in our environment. The sun’s UV rays cause oil migration much the same as it does to exposed asphalt. On this roof a plastic boot was used as a stack flashing to seal the pipe. A gap between the pipe and surrounding flashing is visible and allowing seepage. This boot should be removed and replaced with a new lead boot.
Straight Line is 1 of 5 contractors in California that is certified by all 3 major roofing manufacturers