Pipe flashing is used anywhere pipe or tubing penetrates a buildings roof. It is a thin piece of impervious material that is used to prevent water from passing through a joint, or other susceptible point.

It is made of lead or galvanized steel with a rubber boot and sealed with rubber cement. It is generally installed above bathrooms or kitchens to vent methane gas from sewer system. They come in a variety of sizes from 1 1.5 inch to 5 inch in diameter. If lead, they only need to be changed if damaged by squirrels or other debris breaking them, they should last the lifespan of the roof. If metal or neoprene boot, they will need to be changed in 5 year increments. The sun will crack them.