The answer to 'why is my roof vent water stains' is that there are several common causes, including improper installation, damage to the vent flashing, or issues with the roof's waterproofing. Water stains around a roof vent can indicate that moisture is seeping in, which can lead to leaks and potential water damage if not addressed.
Some of the most common causes of roof vent water stains include poor sealant around the vent, cracks or holes in the vent flashing, and issues with the roof's underlayment or shingles. Over time, the sealant around a roof vent can deteriorate, allowing water to penetrate. Damage to the vent flashing, such as from weather or physical impact, can also create entry points for water. Additionally, if the roof's waterproofing layers are compromised, it can allow water to seep in around the vent.