How do I ensure the prehung door is plumb and square in the opening?
The key to a properly functioning prehung door is ensuring the frame is both plumb and square within the rough opening. This involves using shims to precisely adjust the frame’s position until it is perfectly vertical (plumb) and the top and bottom are level and of equal width (square), then securely fastening it in place.
Ensuring plumb and square starts with a rough opening that is properly sized, typically about 2 inches wider and taller than the prehung door frame. Begin by inserting the prehung door into the opening. Start shimming at the hinge side of the door, placing shims behind the top hinge, middle hinge, and bottom hinge. Use a level to check the hinge side jamb for plumb, adjusting shims as needed until it’s perfectly vertical. Drive one screw through the jamb at each shim location, but don’t fully tighten them yet. Next, move to the strike side of the door. Place shims behind the top, middle, and bottom of the jamb, ensuring the gap between the door and the jamb is consistent its entire length. This ensures the door will close properly without binding. Check the strike-side jamb for plumb, adjusting shims as needed. Also check that the head jamb (the top) is level using your level. Once you’re satisfied, drive screws through the jamb at each shim location on the strike side, again avoiding over-tightening. Finally, test the door’s operation. Open and close the door slowly, checking for any binding or rubbing. Adjust shims as needed to eliminate any issues. Once the door swings smoothly and closes properly, fully tighten all the screws in the jambs. Then, score the shims with a utility knife and snap off the excess for a clean finish before applying casing or trim. A square and plumb frame guarantees a door that operates smoothly and seals correctly.
How do I adjust the door strike plate if the door doesn’t latch properly?
If your prehung door isn’t latching correctly, the first thing to check and adjust is the strike plate. The strike plate is the metal plate mortised into the door jamb that the door’s latch bolt engages with to keep the door closed. Adjustment involves either moving the strike plate slightly up, down, in, or out so that the latch bolt aligns properly with the strike plate’s hole, allowing the door to close and latch securely.
To diagnose the issue, carefully observe how the latch bolt interacts with the strike plate as you slowly close the door. If the latch bolt is hitting the top or bottom of the strike plate opening, the entire plate needs to be adjusted vertically. Loosen the screws holding the strike plate in place. You may need to slightly enlarge the screw holes in the jamb with a drill or file to allow for movement. Gently tap the strike plate up or down with a hammer and a block of wood to protect its finish, then retighten the screws. If the latch bolt is hitting the strike plate on its outer edge and preventing the door from closing fully, the strike plate needs to be adjusted inwards, towards the interior of the house. Sometimes, the strike plate needs to be shimmed outwards if the door is too tight against the jamb. This can be done by placing thin cardboard or wood shims behind the strike plate before reattaching it. Conversely, if the door rattles or doesn’t feel secure when latched, the strike plate might need to be mortised deeper into the jamb. Use a chisel and hammer to carefully remove a thin layer of wood from behind the strike plate before reattaching it. Always make small adjustments and test the door’s latching action after each adjustment to avoid over-correcting the problem. Consider using longer screws to secure the strike plate more firmly to the door frame, especially after adjustments have been made, for added security and to prevent the plate from shifting over time.