Roof Vent Cap Installation
Improperly installed vent flashing can cause substantial damage to a roof. Improperly installed flashings are common when being installed on an existing roof when a bathroom fan is added. It is common to see these installed on top of the roof shingles with sealant applied around the edges. Properly installed, the flange of the vent should be below the shingles on 3 sides, leaving the lower edge exposed on top of the shingles. The attached document shows the correct way to install vent flashings.