What is a flat flush door?

A flat flush door is a door with a completely smooth face, built from a light softwood frame with a core and a skin of sheet material on both sides. In Dutch it is called a vlakke deur. The core is for example cardboard, often in a honeycomb pattern, and the skins are plywood, hardboard or MDF. These doors are factory-made and are the most common type of internal door.

Flush door or flush-fitting door?

In British usage “flush door” describes the face of the leaf: flat and plain, as opposed to a panel door. A flush-fitting door is something else: it describes how the door sits in its frame, level with it rather than lapping over it. A flat flush door can therefore be either flush-fitting or rebated.

Construction

• Frame: a light softwood frame (in the Netherlands usually spruce) around the edges of the leaf.
• Core: cardboard honeycomb in light, cheap doors. Heavier doors have a solid core, for example particleboard, which is stronger and insulates better.
• Lock block: the frame is reinforced at lock height, giving a solid fixing for the lock and furniture.
• Skins: thin sheets on both faces, veneered, laminated or primed.

Application

Flush doors are mainly used as internal doors in housing and commercial buildings. Light hollow-core doors are not suitable as external doors.

Tips

• Trim with care: the frame is narrow. Cut too much off the bottom and you cut through the frame, leaving the skins without support.
• Lock in the right place: only drill or rout at the lock block. Elsewhere there is only core behind the thin skin.
• Fixings on the leaf: screw hooks, door stops or closers into the frame, not into the skin in the middle of the door.
• Sound: a honeycomb door blocks little sound. For a bedroom or study choose a solid-core door.

Related terms

• Interior door
• Flush-fitting door
• Rebated door
• Panel door
• Hardboard
• Spruce wood

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