Things You'll Need
Continuous hinges, often called piano hinges, extend along the entire length of a door opening and consist of two metal leaves connected by a steel pin. Continuous hinges often are used to rehang doors that have been subject to high levels of abuse. Because they are fastened down the length of the frame, they can accommodate frames that have been drilled or damaged repeatedly. These hinges also are used to hang oversized or overweight doors to help improve operational performance over time.
Measure the height of the door frame from the finished floor to the bottom of the frame header. Subtract 7/8 inches from this measurement to determine how long your continuous hinge should be.
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Transfer the measurement to your hinge and mark the location with a pencil. Close the hinge so that the back of each leaf is visible (you will not see the countersunk screw holes). Use your metal saw to cut the hinge to length. File down the edges of the hinge so they are smooth.
Insert a nail into the top of the cut (smaller) section and use a hammer to force the tip of the hinge out of the barrel. This tip is a simple cover that will be reinserted into the bottom of the hinge section you will be installing. Use a hammer to tap it into place. It is important to reinstall this tip so that the hinge pin stays in place once the door is installed.
Connect the hinge to the face of the frame. It should be positioned so that it lies completely flat across the door and frame when the door is closed. Leave a 1/8-inch gap between the top of the hinge and the top of the frame, as well as a 1/16-inch gap between the side of the frame and the centerline of the hinge barrel. Use the screws that come with the hinge to fasten it in place, or use 3/4-inch self-drilling screws. Every pre-drilled hole on the hinge must be filled with a screw, or the hinge may not work properly.
Place the door into the opening and align the top of the door with the top of the hinge. The edge of the door should be 1/16 inch from the centerline of the hinge barrel. Use the enclosed screws or 3/4-inch self-drilling screws to fasten the hinge to the door.
Some continuous hinges have covers. If you buy a unit with a cover, it also will come with cover clips. These cover clips are placed under the head of the screws (like a washer) when they are fastened to the door and frame. You can connect the cover to these clips by hand once you've installed the door.