Installing a pre-hung door may seem straightforward on paper, but for DIYers without much experience it may still prove challenging. Make sure your new door and frame are level, plumb and flush against any drywall surfaces for a successful outcome.
To level a frame (also referred to as a jamb), insert wood shims under each side until it is even. Add additional shims on both the hinge side and latch side as necessary in order to plum the hinge side perfectly.
Measure the Rough Opening
Before installing a pre-hung door, the first step in measuring its rough opening. This space will become home for both frame and jamb once assembled, so for accurate measurements remove all interior trim around your entryway before taking measurements from three points between studs at three different spots and record which measurement has the smallest measurement.
Measure both sides of the rough opening’s height. Both frames should have equal top and bottom surfaces.
Once you have taken measurements, arrange your door and jamb unit in its intended opening. Shim the side jambs as necessary so they are at an acceptable height; too-low bottom frames could interfere with later installations of flooring. Use a level to check that your frame is square before installing the door; if not, nail shims to its framing lumber for adjustment if necessary.
Remove the Existing Door
Installing a pre-hung door can quickly transform the appearance of your home in only a few hours, making an impressive statement without breaking the bank. DIYers with basic carpentry knowledge can tackle this project without much difficulty; just ensure that all measurements are taken accurately so as to save yourself any unnecessary aggravation!
Before beginning, close and latch your existing door in order to easily dismantle its hinge pins. Begin at the bottom and work your way upward, using a pry bar for leverage if necessary. Though this may take some effort and strength, you should be able to remove these pins without damaging either trim or drywall.
Once complete, take the necessary steps to tidy up the rough opening by clearing away debris from previous frames, sanding down jambs to prepare them for cementing, caulking gaps, joints and corners to protect against leaky doors causing water damage – you can find caulking as well as paintable sealants from most hardware stores.
Remove the Jambs
Shimming a pre-hung door may be necessary unless your wall is perfectly level and plumb; evenly spaced shimms should be added throughout its frame to ensure it opens and closes correctly.
Before beginning, apply a bead of caulk along the back of brick molding at the hinge side of the frame to keep drywall screws from pulling out when nailing them in. This will prevent their removal during nailing sessions and help ensure smooth results.
With hinge pins removed and door trim loosened with a utility knife, carefully pry off the frame from its hinges with help from a partner so you can control as the door slides off its hinges. Shim the latch side jamb if necessary if its level drops lower than hinge side jamb; use a 4-foot level on floor and center its bubble over both hinge and latch jambs; if the level dips lower on latch side jamb, use shims under it until its bottom meets studs flush.
Shim the Door
Before installing your new door, first ensure the existing frame is square with its surroundings using a level or plum bob. A framing square should also be used to check trimmer studs are square to their walls.
Start on the hinge side and add wood shims until a gap equal to the thickness of your door handle between it and the wall is created between door frame and wall. Adjust shim locations on latch side as necessary.
Use a level to check that the frame is plumb and centered in its opening before using 4D finish nails to tack through shims and into framing lumber, using utility knives if necessary to score and snap off excess shims. Paint or stain them to match surrounding frame trim or your new door and install doorknob, lockset, strike plate hardware as necessary.