Stop Sagging Doors
Nov 1, 2000 12:00 PM, By Bob Cronk
- Full surface mounting. Full surface continuous geared hinges are installed on the face of a door and frame. This profile usually is used in retrofit situations, but also can be used with new doors and frames. The hinge is installed with 12-24 fasteners in the frame leaf, and fastened with sexnuts and 1/4-20 shoulder screws through the door. Full surface hinges also usually are designed with four locator holes per hinge to aid in the adjustment of the door to fit plumb and square in the entrance opening before installation of the door and frame fasteners. This profile can be used on aluminum, wood and hollow metal doors up to 21/4-inch thick. A common use for full-surface hinges is on school building doors that have sagged due to damage or wear on the original butt hinge or pivot.
- Half-surface mounting. Half-surface continuous geared hinges are installed on the face of a door, with the frame leaf concealed. This profile usually is used in retrofit situations, but also can be used with new doors and frames. The new door must be undersized by the clearance needed at the lock side of the door, plus 3/16-inch (1/8-inch frame leaf + 1/16-inch clearance = 3/16-inch) on the hinge side. The frame leaf is installed on the rabbet of the frame with 12-24 fasteners, and the door leaf is through-bolted to the door surface with sexnuts and 1/4-20 shoulder screws. This profile can be used on aluminum, wood and hollow metal doors up to 21/4 inches thick. A common use for half-surface hinges is on school building doors that have been weakened at the hinge edge, but the door itself is still serviceable.
Continuous geared hinges are available with fire ratings ranging from 20 minutes to 3 hours. Some concealed, full- and half-surface hinges need pins or studs to be fire-rated. Most manufacturers have gained approvals for positive pressure fire ratings.
Continuous geared hinges have improved since they were introduced more than 25 years ago. Modern continuous geared hinges have templated hole patterns, lubricated bearings, permanent lubricants on the geared areas (which nearly eliminate maintenance needs), extended wear life, non-handed design, stainless-steel fasteners, security features, electrical modifications and decorative hinge caps.
The Builders Hardware Manufacturers Association (BHMA) is working on establishing a cycle test standard for continuous geared hinges.
Continuous geared hinges are manufactured in standard industry lengths (79, 83, 85, 95 and 119 inches) that allow for threshold clearance in most openings. Mounted flush with the top of the door and allowing 1/8-inch header clearance, standard length hinges allow 7/8-inch clearances at the bottom. Hinges can be cut to exact lengths on site, or at the factory. After cutting, a non-handed new continuous hinge may become handed, depending on the model. Most hinges are finished in 628 (US28) clear anodized aluminum, or 313AN dark bronze anodized duranodic colors. Custom anodizing and painting allow the hinges to be matched with other hardware finishes.
A properly installed continuous geared hinge can easily last 10 to 20 years or longer in an entrance and tolerate a great deal of abuse and heavy traffic with little or no maintenance required.
