Door hinges are specified under ANSI/BHMA A156.1 (Butts & Hinges), with template dimensions in A156.7 and continuous hinges in A156.26. A complete specification names the hinge type, grade, size selected by door width and weight, bearing type, base material and finish, and pin type — including non-removable pins on out-swing exterior and secure openings.
Hinges are the least glamorous line on a door hardware schedule and the one most often left to “match existing” or a distributor’s default. That is a mistake on commercial and multifamily work, where a hinge carries the full weight of the door through hundreds of thousands of open-and-close cycles. Undersized or under-graded hinges sag, bind the latch, and pull screws out of the frame long before the rest of the opening wears out. This guide covers the three hinge families a finishes package deals with, how each is sized and graded, and the confirmations that keep a hinge schedule from failing an inspection or a first-year warranty walk.
The three hinge families
Full-mortise butt hinges. The standard leaf hinge: two leaves joined by a pin, each mortised into the door edge and the frame rabbet. This is the default for the overwhelming majority of swinging doors in both multifamily units and commercial corridors. Butt hinges are governed by A156.1 and dimensioned to the templates in A156.7, which is what makes a hinge from one manufacturer interchangeable with the prepped door and frame from another.
Continuous (geared and pin-and-barrel) hinges. A continuous hinge runs the full height of the door edge, distributing load along the entire opening rather than at two or three points. Governed by A156.26, continuous hinges are specified on high-abuse and high-frequency openings — stairwell doors, high-traffic corridor and amenity doors, and heavy doors that would otherwise wrack a butt-hinge frame prep. They resist sag, resist door drop, and eliminate the pinch points that make butt-hinged doors an accessibility and finger-injury concern.
Concealed (SOSS-type) hinges. Concealed hinges mortise entirely into the edges of the door and frame, leaving nothing visible when the door is closed. SOSS is the brand name most specifiers use as shorthand for this invisible-hinge category. They are a design-intent product — used where a flush, minimalist, or hardware-free look matters, such as concealed doors in amenity spaces and high-design unit interiors. Concealed hinges are selected by model to a rated door weight and thickness; they are not a high-cycle commercial substitute for a butt or continuous hinge.
Sizing by door width and weight
Hinge size is not a guess. Hinge height is driven by door thickness and width, and hinge weight class (standard vs. heavy) is driven by door weight and frequency of use. The reference table below covers the common cases in interior finishes scope.
| Door condition | Typical hinge | Quantity | Notes |
|---|---|---|---|
| 1-3/8" interior unit door, ≤ 36" wide | 3.5" or 4" standard-weight butt | 2–3 | Grade 2/3 acceptable for low-traffic interior |
| 1-3/4" door up to 36" wide | 4.5" standard-weight butt | 3 | Most commercial and unit-entry openings |
| 1-3/4" door 37"–48" wide, or heavy | 4.5"–5" heavy-weight butt | 3–4 | Upsize for width and door weight |
| High-frequency / high-abuse opening | Continuous (geared) hinge, A156.26 | 1 full-height | Distributes load along full edge |
| Flush / concealed design intent | Concealed (SOSS-type), rated to weight | per model | Design product, not high-cycle rated |
Hinge quantity follows the height rule: two hinges up to a 60-inch door, three up to 90 inches, four up to 120 inches — one additional hinge for every 30 inches of height. Heavy or high-frequency leaves get upsized before they get more hinges.
Grades and bearings
A156.1 grades hinges by cycle testing, mirroring the familiar Grade 1 / Grade 2 / Grade 3 tiers. Grade 1 is the commercial and high-traffic standard; Grade 2 and Grade 3 step down for lighter residential interior use. On the bearing question:
- Ball-bearing hinges carry the load on bearings between the knuckles, dramatically reducing friction and wear on heavy or frequently used doors. Any door with a closer, any heavy door, and essentially all commercial openings should be ball-bearing. When precise, cite the standard family (A156.1) rather than a specific cycle count you cannot verify for a given model.
- Plain-bearing (plain-bushing) hinges are acceptable only on light, low-frequency interior doors — a unit closet or a passage door with no closer.
The failure pattern is predictable: a plain-bearing hinge under a door closer squeals within months and wears loose within a year or two. Specify ball-bearing wherever a closer, weight, or traffic is present.
Non-removable pins and material
On any out-swing door where the hinge barrel is on the exterior or non-secure side, the hinge pin is reachable — and a standard loose pin can be driven out to defeat the door. Specify NRP (non-removable pin) hinges, or security-stud hinges, on out-swing exterior doors and on secure interior openings (electrical, IT, storage, and mechanical rooms). This is a code- and security-driven confirmation, not an upgrade.
Base material tracks environment: steel for interior painted-jamb openings, stainless steel or a corrosion-resistant finish for exterior and wet-area openings. Finish must coordinate with the rest of the opening’s hardware finish package — a satin nickel lever with a bright chrome hinge reads as an error on a walkthrough.
What Innergy confirms and how we spec hinges
On Innergy projects, hinges are scheduled per opening alongside the rest of the door hardware, not defaulted to a distributor’s box quantity. For each opening we confirm the hinge height and weight class against door width, thickness, and weight; specify ball-bearing on every closer-equipped and heavy door; and flag every out-swing exterior and secure opening for NRP pins. We match hinge finish to the opening’s finish package so the schedule reads as one coordinated selection.
We also confirm that continuous hinges are called out on the openings that actually need them — high-abuse stairwell and amenity doors — rather than blanket-applied at cost, and that any concealed SOSS-type hinge is rated to the real door weight rather than chosen on appearance alone. This is the same door-schedule discipline covered in our door hardware specification guide for multifamily construction, applied to the hinge line specifically.
Related door hardware specifications
Hinges are one line on the opening. The lock or latch that follows is covered in our mortise and cylindrical lock specifications, the door control in our door closer specifications, and the operable trim in lever, knob, and handleset specifications. On egress openings, coordinate the hinge with the exit and panic device specifications, since a panic-device door is almost always a continuous-hinge candidate.
Door hardware falls in our Division 8 openings, mirrors, and shower doors scope for multifamily and commercial projects. To have a coordinated hinge and hardware schedule reviewed before procurement, contact us and we respond within one business day.