4 Inch Self-Closing Door Hinge

The Waterson 4-inch self-closing door hinge (Model K51M) combines an overhead door closer and hinge into a single unit, eliminating the need for separate closing hardware. At 4 inches tall, it fits standard residential and light commercial door preparations. Features include adjustable hydraulic closing speed, UL 3-hour fire rating, ADA-compliant settings, and available corner radius options of 1/4" or 5/8" to match existing door hardware.

What Is a 4-Inch Self-Closing Door Hinge?

A 4-inch self-closing door hinge is a combined closer-hinge unit where the automatic closing mechanism is built directly into the hinge barrel — rather than being a separate overhead closer mounted above the door. The "4 inch" refers to the height of the hinge leaf, which is the standard minimum size for Waterson's closer-hinge product line.

The K51M model integrates:

• Spring mechanism — Provides the closing force that pulls the door shut
• Hydraulic buffer — Controls closing speed to prevent slamming and meet ADA timing requirements
• Adjustment panel — Numerical settings for both spring tension and hydraulic speed, adjustable with a standard hex key

This self-contained design eliminates the visible overhead closer arm and track, producing a cleaner aesthetic while meeting all code requirements for self-closing doors.

Applications: Where to Use a 4-Inch Self-Closing Hinge

The 4-inch size is particularly suited for residential and light commercial applications where smaller hinge mortise preparations are standard:

Hinge Count and Placement for 4-Inch Hinges

Correct hinge quantity and placement significantly affects the performance of self-closing hinges. Waterson recommends the following approach:

On fire-rated door assemblies, three self-closing hinges are typically required to meet NFPA 80 performance standards for heavier fire-rated doors.

Corner Radius Options and Screw Patterns

Self-closing hinges used as replacements or upgrades must match the existing hinge mortise preparation in the door and frame. Waterson K51M 4-inch hinges are available in multiple corner configurations:

Screw patterns are available in zig-zag (standard commercial template) and architectural arch configurations to match existing door preparations and avoid wood splitting in replacement applications.

ADA Compliance and Closing Speed Adjustment

Residential doors on accessible routes — such as apartment entry doors or accessible unit entry doors — must comply with ADA and ICC A117.1. The Waterson K51M self-closing hinge satisfies these requirements through its dual-adjustment system:

• Spring tension adjustment — Reduces opening force to below the ADA maximum of 5 lbf for interior doors
• Hydraulic speed adjustment — Slows closing to meet the ICC A117.1 minimum of 5 seconds from 90° to 12°

These two adjustments work independently, allowing installers to meet both the force limit (for accessibility) and the closing time minimum (for self-closing function and fire code) simultaneously on the same door.

Fire Rating and NFPA 80 Compliance

The Waterson K51M 4-inch self-closing hinge is UL-listed with a 3-hour fire rating — the highest available for self-closing hinges. This makes it suitable for any fire-rated door assembly from 20-minute to 3-hour ratings, including:

• Residential unit entry doors in apartment buildings
• Fire-rated door between attached garage and living space
• Stairwell and corridor fire doors in multifamily buildings
• Mechanical room and utility space fire-rated doors

Important: when using the 4-inch K51M on fire-rated assemblies, the hold-open feature must not be activated. NFPA 80 requires fire doors to self-close and latch from any open position without being held open.

Available Finishes

The Waterson K51M 4-inch self-closing hinge is available in multiple finishes to match door hardware specifications:

Frequently Asked Questions

Q: What is a 4-inch self-closing door hinge?

A 4-inch self-closing door hinge is a combined closer-hinge unit that integrates an automatic door closing mechanism into a standard hinge body. The 4-inch measurement refers to the hinge leaf height. Unlike a traditional door hinge that only pivots, a self-closing hinge contains an internal spring and/or hydraulic system that automatically pulls the door shut after it is opened, eliminating the need for a separate overhead door closer.

Q: How many 4-inch self-closing hinges do I need for a door?

Waterson recommends starting with two self-closing hinges for residential applications and adding a third if needed for heavier doors or stronger closing action. The top hinge placement is most critical for self-closing function — it generates the most return torque. For doors over 200 lbs or commercial applications, three hinges are standard, with four available for doors up to 440 lbs.

Q: Are 4-inch self-closing hinges ADA compliant?

Yes, when properly adjusted. ADA requires interior door closing force under 5 lbf and closing time of at least 5 seconds from 90° to 12° per ICC A117.1. The Waterson K51M 4-inch self-closing hinge features adjustable hydraulic speed control and spring tension that can be field-set to meet both requirements simultaneously.

Q: Can 4-inch self-closing hinges be used on fire-rated doors?

Yes. Waterson 4-inch self-closing hinges carry a UL-listed 3-hour fire rating and comply with NFPA 80 self-closing requirements. They are an approved alternative to overhead door closers on fire-rated door assemblies. Note: the hold-open feature must not be installed on fire-rated doors, as NFPA 80 requires fire doors to close and latch from any open position.

Q: What corner options are available for 4-inch self-closing door hinges?

Waterson 4-inch self-closing hinges are available with 1/4-inch radius corners or 5/8-inch radius corners (to match existing door or frame preparations), in both zig-zag and architectural arch screw patterns. The door side and frame side can have different corner profiles for custom applications. Standard lead time is approximately 30 days for non-standard corner combinations.