A hollow core door is an interior door without solid materials in its frame. These doors are lightweight and used in many types of buildings. These doors don't buffer sound well, but are an affordable alternative to solid core wood doors.
Scrap woods and artificial wood finishes are typically used for hollow core doors. The lower cost materials help keep the price of these lightweight interior doors inexpensive. This type of door is considered quite environmentally friendly because manufacturers can use up wood products that would otherwise be wasted. Before the manufacturing of hollow core doors, scrap woods were routinely discarded as waste.
While the hollow core door is certainly not heavy or solid, is it also not completely empty inside its frame. These doors need some type of inner structure to add some support to the frame and there are a few different types of hollow core structures used today. One common type of door filling is structural paper. The paper is often formed into a honeycomb construction and is glued to fit inside the hollow door frame. Other types of support filling for hollow core doors include foam blocks and pieces of board placed in sections inside the door frame.
Hollow core doors should not be used for exterior doors as they are too easy for an intruder to break through. These doors are meant as all-purpose affordable interior doors only. Since they don't look as elegant as good wood doors or have the same sound resistant quality as solid core doors, hollow core doors are often replaced with quality solid upgrades once home owners can afford renovations.
Some frugal decorators salvage hollow core doors and transform them into temporary or even permanent pieces of household furniture. For example, a hollow core door placed on top of two filing cabinets can create a handy desk. Headboards can be made by covering a hollow core door with mirrors or foam and fabric. It is possible to create a large chalkboard out of a hollow core door by painting it with blackboard paint.