Siding can be vulnerable for two reasons. First, if ignited, combustible siding can provide a path for flames to reach other vulnerable components of your home, such as a window or the under-eave area. Second, if penetrated, a horizontal or vertical lap joint will provide access for flames to enter the structure.
If you currently have combustible siding, incorporating a noncombustible or low-combustible zone next to your home will reduce the vulnerability of your siding.
Replacing existing siding can be expensive. There are some less expensive options such as the use of metal flashing.
Paying careful attention to the vegetation management in the area immediately adjacent to your home will enhance the sidings protection regardless of the material.