Full Overlay, Half Overlay and Inset Hinges: Definitions and Differences
Full overlay, half overlay, and inset configurations define the precise position of a furniture door in relation to the cabinet carcass. With a full overlay, the door completely covers the side panel. A half overlay is used for central partition walls where two doors meet. With an inset fitting, the door sits completely flush inside the carcass openings.
What Exactly Do Hinge Overlay Types Define?
Choosing the correct hinge from the range of concealed hinges / cabinet hinges depends entirely on the design of the piece of furniture. The mounting type determines how far the closed door covers the edge of the carcass side. Technically, this difference is achieved through the hinge arm crank. The crank acts like a mechanical elbow angled at different depths depending on the overlay type, ensuring the door swings smoothly past the cabinet side during opening.
The Three Overlay Types in Detail
Full Overlay (Straight Arm)
The full overlay is the standard solution for individual cabinets. Here, the closed furniture door covers almost the entire front edge of the outer carcass wall. Only a minimal gap reveal remains (usually 1.5 mm to 2 mm) to prevent the door from catching on adjacent units when opened. Fittings designed as full overlay concealed hinges feature a straight hinge arm with a crank of 0 mm.
Half Overlay (Dual Mounting / Twin Application)
The half overlay configuration is used when a wider cabinet is divided by a vertical central partition wall, requiring doors on both the left and right to mount onto this single partition. Because two doors share one carcass side (typically 16 mm or 19 mm thick), each door must only cover half of the panel thickness. Half overlay concealed hinges therefore feature a medium crank of around 9.5 mm.
Inset (Cranked Arm)
With an inset door, the front does not rest in front of the carcass frame; instead, it sits completely inside the cabinet opening. The front face of the door sits flush with the front edges of the cabinet side panels, base, and top panel. To swing the door clearly out of the carcass during opening, inset concealed hinges require a prominent crank of usually 16 mm to 18 mm. Alternatively, these fittings are specified simply as hinges for inset doors.
Dimensions, Standards, and Typical Values
Regardless of the overlay type, modern concealed furniture hinges share standard dimensions crucial for installation:
- Cup Drilling: The drilling diameter for the hinge cup in the door is almost always 35 mm for standard applications. Fittings in the 35 mm concealed hinges category cover most furniture building projects.
- Drilling Pattern: The hole spacing for fixing screws beside the hinge cup varies by manufacturer (e.g. 45 mm, 48 mm, or 52 mm).
- Opening Angle: The standard for conventional cabinet doors is 110°. Matching 110-degree concealed / cabinet hinges allow comfortable, wide access to the cabinet interior.
- System 32: Mounting plates inside the carcass are generally fixed within the standardised 32 mm hole pattern, typically 37 mm back from the carcass front edge.
Application and Selection
Choosing the correct hinge begins with the furniture technical drawings. To achieve an even gap reveal, every modern concealed hinge provides three-dimensional adjustment screws (depth, height, and lateral overlay).
Alongside the mounting type, additional mechanisms determine convenience. For silent door closure, soft-close concealed hinges / cabinet hinges are standard modern choices. These incorporate an integrated hydraulic damper directly inside the hinge arm or hinge cup, gently decelerating the door over the final centimetres of movement.
Related Terminology
- Cruciform Mounting Plate: The mating plate for the concealed hinge, screwed directly onto the interior carcass wall.
- Gap Reveal: The essential clearance between two doors or between a door and adjacent panels to prevent moving parts from colliding.
- Hinge Hole Cutter: The specialised drill bit (Forstner bit) used to bore the precise 35 mm recess into the furniture door.