Exterior fiberglass doors have a stiff insulating core, are clad in fiber-reinforced polymer, and have an artificial wood grain applied to them.
Doors made from fiberglass tend to survive a long time. Fiberglass is impervious to the effects of moisture and humidity; therefore it won’t warp like wood will. It won’t corrode or rust either. However, fiberglass can be dented or fractured with enough force.
Insulation is a major concern in many parts of the world, yet fiberglass doors are ideal since they can withstand extremes of temperature and humidity. They will not rust like steel doors do in damp environments.
A fiberglass exterior door will never need painting or staining and can last up to 20 years if installed in a decently protected area.
Doors made of wood are sturdy, but they deteriorate after being exposed to the weather for too long. Unlike wood, fiberglass doesn’t rot, split, peel, or delaminate with time, and it can withstand far more severe weather conditions without deteriorating.