What Is a Butt Hinge? The Traditional Door Hinge Explained

What Is a Butt Hinge? The Traditional Door Hinge Explained

A butt hinge is the classic, widely used hinge for internal and external doors; it consists of two rectangular leaves joined by a central pin. One leaf is morticed into the door edge and the other into the frame so the leaves sit flush when the door is closed. Butt hinges are found across timber door applications in domestic and commercial settings because they are simple, robust and easy to fit or replace.

Components and how they work

The basic components of a butt hinge are:

• Two leaves: flat plates with countersunk screw holes that sit into a mortice in the door and frame.
• A central pin: removable or fixed; it forms the pivot and may include ball bearings for smoother action.
• Knuckle: the cylindrical sections that wrap around the pin; number of knuckles affects strength and aesthetics.

When properly morticed, butt hinges allow the door to close flush with minimal projection. They are available in a variety of sizes and finishes to suit internal timber doors, external entrance doors and fire doors.

Materials, finishes and suitable uses

Common materials include brass, steel and stainless steel. Brass is popular for traditional or decorative internal doors; stainless steel is the preferred choice for external doors and damp environments because of its corrosion resistance. For high-traffic or heavy doors, choose ball-bearing butt hinges to reduce wear and ensure smoother operation.

• Brass: aesthetic, but can wear faster on heavy use without bearings.
• Stainless steel: durable and corrosion resistant; suitable for external doors and coastal locations.
• Ball-bearing variant: recommended for heavy or frequently used doors; bearings reduce friction.
• Fire-rated hinges: specially tested and marked for fire doors; always check certification when used on fire doors.

Common sizes and selection tips

Hinge size is expressed as the leaf length by leaf width: common sizes in the UK include 75mm, 100mm and 127mm lengths. Typical guidance when selecting a butt hinge:

• Lightweight internal doors: 75mm to 100mm hinges; two hinges are usually sufficient.
• Solid internal doors or external doors: 100mm to 127mm; consider three hinges for heavy doors.
• Heavier timber doors or commercial entrance doors: use larger hinges with ball bearings and longer screws for secure fixing.

Screws: use appropriate length and gauge to reach the frame or a blocking/jamb. As a rule of thumb use screws long enough to bite at least 25mm into the frame; typical diameters are 4mm to 5mm for domestic doors. Countersunk wood screws are standard; stainless screws should be used with stainless hinges to avoid galvanic corrosion.

Fitting a butt hinge: practical trade and DIY guidance

Fitting a butt hinge requires accurate marking and neat morticing so the door closes flush. Basic steps and tips:

• Mark hinge positions: a common layout is 200mm from the top for the top hinge and 180mm from the bottom for the bottom hinge; place a third hinge equidistant between them for heavier doors.
• Mark the outline on the door and frame: hold the hinge in place and trace around the leaf; transfer the same position to the frame edge.
• Mortice the rebate: use a sharp chisel or router for a neat mortice to the same depth as the hinge leaf thickness; aim for tight joints so the hinge leaf sits flush.
• Pilot holes: always drill pilot holes for screws to avoid splitting; countersink where needed so screws sit flush.
• Test pinning: fit the hinge pin temporarily to check alignment before screwing permanently; close the door and confirm even gaps around the door.
• Adjustments: if the door binds, plane small amounts from the door edge or adjust the depth of the mortice; use thin shims behind the hinge leaf in the frame to correct minor alignment issues.

Tools commonly used by tradespeople include a mortice gauge, sharp chisels, a router for speed and accuracy, and a cordless driver with appropriate torque control. For replacement work where the mortice is already present, check for wear; a worn mortice can be strengthened with hardwood inserts or epoxy resin and refitted for a secure fixing.

Maintenance and common problems

Butt hinges are low maintenance but do require attention if problems occur:

• Squeaking: usually cured with a suitable lubricant applied to the pin; remove the pin if possible and apply grease or light oil then work the hinge.
• Loose screws: tighten or replace with slightly longer screws to reach solid timber behind the face of the frame.
• Wear and sagging: signs of knuckle wear or elongated screw holes indicate replacement; upgrade to stainless steel or ball-bearing hinges if usage is heavy.
• Corrosion: swap to stainless steel if hinges are corroding, especially in coastal or high-humidity environments.

Regulations and safety considerations

When working on external doors or certified fire doors, ensure hinges meet relevant performance standards and markings. Fire doors require hinges that are tested as part of the door assembly; uncertified hinges on a fire door can compromise the door's performance. For external access doors consider security screws or reinforced fixings to resist forced removal.

Replacing a butt hinge

For a straight replacement match the hinge size and screw positions where possible. If upgrading to a heavier hinge or adding a third hinge, you may need to cut new mortices and fill old ones neatly. For retrofit installations on older frames use long screws that penetrate into the structural timber behind the lining for greater strength.

Recommended Products

Based on this article, you may find these products helpful:

• Flag Door Hinge - Stainless Steel
• Adjustable Flag Hinge - 100mm
• ERA Challenger 3D Rebated Hinge
• Challenger Door Hinge
• UAP Adjustable Hinge for Composite Doors

Conclusion and next steps

Butt hinges are the traditional, reliable solution for most timber doors; selecting the correct size, material and fixing method makes the difference between a door that hangs accurately for years and one that requires frequent adjustment. For trade projects choose ball-bearing and stainless options for heavy or external doors; for DIY replacements follow careful marking and morticing practice and use appropriate screw lengths and pilot holes.

Next steps: refer to our pillar page for door hinge options at /guides/door-hinges for more detailed comparisons and specifications; contact your supplier for recommendations on hinge sizes and finishes for your specific door; if working on a fire door check the required certification before replacing hinges.