The white pipe sticking up out of the roof is a plumbing vent. The rubber boot at the base of the plumbing vent is part of the flashing kit for this vent, and the boot has dried out and split. Here's ...
Plumbing vent boots can be all plastic, plastic and metal, or even two-piece metal units. Check plastic bases for cracks and metal bases for broken seams. Then examine the rubber boot surrounding the ...