Standard flush Hinges should be flush with both the door panel and the door frame. This “flush installation” is a distinctive feature of this type of hinge. To achieve this effect, a shallow groove—known as a mortise—is cut into both the edge of the door panel and the door frame.

Why “Flush” Is the Standard Practice

Proper flush installation is not only a matter of aesthetics; it is also crucial to the functionality and service life of the door panel:

· Strength and Stability: The mortise and tenon joints create a mechanical interlocking structure, providing far greater load-bearing capacity than simple surface mounting.

· Sleek and Professional Appearance: This installation method minimizes the gap between the door and the frame, creating a clean, professional visual effect.

· Smooth Operation: Properly recessed hinges ensure the door opens and closes freely without catching on the frame.

How to Achieve a Flush Installation

To achieve a perfect fit, the mortise must be carefully cut so that its depth matches the hinge plate exactly. A common mistake is cutting the mortise too deep, which can cause the door panel to jam or install crookedly.

Key Tip: The hinge plate should be completely flush with the wood surface. If the door is to be painted, some professionals even recommend that the hinge protrude slightly (about the thickness of one or two business cards) from the surface. This slight allowance ensures that after applying primer and finish, the hinge will truly be flush with the surface.

When Is a “Non-Flush” Installation Acceptable?

Although “flush” is the basic principle, there are two key exceptions:

·Flush hinges (a different type): Despite the similar name, this is a special type of hinge designed for surface mounting without the need for mortise holes. It features one leaf that slides into another. These hinges are typically suitable for lightweight door panels, such as cabinet doors, but are not recommended for heavy-duty or high-traffic doors.

·Fixing Doors That Are Too Small: In rare cases, when a door panel is cut smaller than the door opening, a surface-mounted (non-flush) hinge may be used on one side as a shim to improve the fit between the door panel and the opening. This is a workaround and not a best practice.

In short, to achieve a secure, stable, and professional-looking door installation, the hinges must be flush with the door panel. If you are installing lightweight cabinet doors or doors that are unusually small, there are other options available.