Which door type has its entire core filled with solid material?

• A. Purlin
• B. Solid-Core Door
• C. Rafter
• D. Ridge

Answer: (B)

Understanding door core types helps you know why a solid-core door is described as having a solid interior. In a solid-core door, the interior material fills the entire thickness, made from dense wood, particleboard, or similar solid substance, so there are no hollow spaces. This adds weight, strength, and better fire resistance and sound dampening. Hollow-core doors, by contrast, have empty cavities inside and are lighter and cheaper but not as strong or soundproof. The other items are not doors at all; purlin, rafter, and ridge are roof structural members—horizontal supports and the peak where rafters meet. So the door type with its entire core filled with solid material is the solid-core door.