How Offset Pivot Hinges Work

How They Work

• An offset hinge swivels on pivots on tabs that project slightly from above and below the door, rather than being in-line as are traditional hinges. In common with most hinge types, they have two plates, but the plates are mounted at the top and bottom of the door, not on the edge opposite the latch. Each plate is properly called a “leaf.” An offset hinge can be located with the tab projecting forward or behind the door -- depending on your direction of travel -- so recessed doors can open without trapping on the edge of that recess.

Installation

• The door-mounted components of offset pivot hinges are recessed, a practice properly referred to as “mortising,” into the top and bottom rails of doors. When fully mortised, the outer face of the hinge is flat and level with the outer face of the wood into which it has been recessed. The stationary counterparts are mortised into the door frame at the top, and either recessed into or mounted onto the floor at the bottom. It is imperative that the mortises cut for the hinge components are perfectly square, level and straight; any variances will prevent the door from opening smoothly and could create a juddering sensation. If the mortises in the door and the frame do not align exactly, the door can trap in regular use and can jump its hinges if slammed.

Terminology

• Referencing the offset size is done from an imaginary line along the center of the top or bottom of the door where the leaf is to be mortised: If the pivot is 3/4 inch forward of the center line, this is a 3/4-inch offset pivot. While 3/4 inch is the standard offset, 1 1/2-inch offsets are available.

Options

• Offset pivot hinges are manufactured in numerous configurations that offer alternative mounting options and pivot points. All have in common that, when in place, they are far more concealed than regular hinges: With the door closed, only the small tabs of the offsets that project out from under and above the door are visible. This is desirable, for instance, in the manufacture of fine cabinetry and expensive, imposing custom doors. Modern versions are manufactured with needle roller bearings and needle roller cage assemblies. Companies that specialize in their manufacture offer them in a wide variety of finishes. A version called an “asylum pivot” can be purchased with sloping, rather than square, top leaves; this adaption is intended to stop people hanging themselves from the projection.