The answer to 'why is my fascia leaking' is that the fascia board, which runs along the roof's edge, is likely damaged or improperly sealed, allowing water to penetrate. This can be caused by weathering, poor installation, or rotting wood. Symptoms may include visible water stains, mold growth, or peeling paint on the fascia.
To fix a leaking fascia, you'll need to inspect the area closely and determine the root cause. This may involve replacing damaged fascia boards, sealing gaps and cracks, or addressing any underlying roof issues that are causing the leak. While some minor fascia repairs can be done DIY, it's often best to call a professional roofer, especially if the damage is extensive or the cause is unclear.