Does your home have exterior doors that are unprotected? Many homes have a flat, unprotected exterior wall with a door. This is common for both front and back doors and was a particularly popular design for the front of homes built in the 1980s. The problem with this style is the exposure the exterior doors often receive. Ultraviolet rays from the sun will damage basically any surface over time, especially if that surface is not maintained correctly. The most significant (and costly) damage is usually from rain.