The answer to 'why is my flat roof water stains' is that water stains on a flat roof are often a sign of a leak or other roofing issue. Flat roofs are more susceptible to water pooling and leaks due to their lack of slope, which can lead to water stains appearing on the ceiling or walls below.
Common causes of flat roof water stains include poor drainage, damaged or worn roofing materials, improper installation, and even debris buildup. If left unaddressed, these issues can lead to more serious problems like mold, rot, and structural damage. It's important to address the root cause of the water stains to prevent further damage to your home.