The answer to 'what causes fascia' is that fascia boards are the horizontal boards that run along the lower edge of a roof, connecting the roof to the exterior walls of a home. Fascia boards serve several important functions, including:
1. Providing a finished edge for the roof: Fascia boards create a clean, uniform look where the roof meets the walls, covering any exposed rafter tails or roof sheathing.
2. Supporting the roof gutters: Fascia boards provide a sturdy mounting point for the home's rain gutters, allowing them to be securely attached to the structure.
3. Protecting the roof structure: Fascia boards help to protect the ends of the roof rafters from weather damage, preventing rot and deterioration.