Prehung doors slot into existing door openings. If you’re ready to install your own prehung door for a DIY project, follow this step-by-step guide as you work.
- Assemble equipment. To successfully install a prehung door, you will need the prehung door itself, wood shims, nails, a hammer, a hand saw, a circular saw, a file, sanding equipment, a tape measure, and a pencil. Depending on your door model, you may also need extra hardware like a strike plate.
- Unwrap the door. Keep the prehung door in its packing restraints until you are ready to install it. This will keep it stable and prevent it from swinging. (Prehung door frames can be surprisingly flimsy until they are bolted to a wall.)
- Prepare your rough door opening for installation. Your opening should be a half-inch wider and taller than the prehung unit you’re about to install. Make sure all surfaces are completely level with no twists and no nails or screws sticking out of the rough opening.
- Trim your door jamb to fit the opening. Use one of your saws, a file, or a sanding device to trim your door jamb to the necessary size. Plan on a two-inch gap between the bottom of your door and an unfinished floor, or a half-inch gap between the bottom of your door and a floor with finish.
- Level and attach the hinge side of the doorframe. Start installing the door on its hinge side. You can temporarily hold it in place using wood shims and finishing nails.
- Move on to the latch side. Once your hinge side is set in place, move on to the latch side of the doorframe. Once again use shims and finishing nails to attach the frame to the rough door opening.
- Attach the top of the frame. Insert a shim into the very top of the prehung unit. Nail it in with finish nails.
- Continue to add shims where needed. A typical prehung door will have wood shims every foot (twelve inches) to hold it in place and maintain its rectangular shape.
- Finish with plaster and trim. With the prehung door properly nailed into the rough opening, you’re ready to add plaster and door trim to finish the project on an aesthetic level.
