Say you split a hollow-core door vertically in half. Inside, you’ll see three layers — two veneer or exterior paneling layers and an interior honeycomb-patterned cardboard layer. Connecting these three layers is a wooden frame.
The honeycomb-patterned cardboard layers make hollow-core doors less expensive and lighter to apply. But it’s air-filled, meaning it’s more prone to noise transfer than other solid-core or wooden doors.
