Door materials1. Solid wood: Solid wood doors can be made from a wide variety of woods, which makes a difference in the overall price. Hard and soft woods, including cherry, mahogany, alder, maple, pine and others are used fairly often, although the most common solid-wood door is the 6-panel pine door. These doors are generally used on exteriors, but may occasionally be used indoors. Keep in mind that solid wood will shrink and expand with changing temperatures and humidity, so it's best not to use solid wood doors for a bathroom, sauna or other damp setting. 2. MDF: Most interior doors today are made of medium density fiberboard. MDF as it's called is an engineered product, so it's very stable and won't warp like wood. It also doesn't have any grain, so it's entirely smooth and very easy to paint. 3. Hollow core: These doors are usually made of plywood or molded composite skin. They tend to be less expensive because the inside of the door panel is hollow. But this means that sound and temperatures can pass through the door more easily.4. Solid core: Like a hollow-core door, a solid-core door has an exterior
skin made of plywood or a molded composite. But a solid core door is filled with a wood fiber blend. These doors have much better sound deadening and temperature control qualities than a hollow core door, but are still not as expensive as a completely solid wood door.