Installing a pre-hung door in your house can be relatively straightforward with some basic hand and power tools, including utility knives, hammers and tape measures as well as drills, cordless screwdrivers and 48″ or longer levels.
Learn the fundamentals of framing by becoming acquainted with terms like jack stud, header and trimmer stud. Once familiarized, follow these steps for a smooth installation:
Measure Your Door
Before beginning installation, it is a good idea to take measurements of your door opening in order to ascertain what size pre-hung door you should purchase. Furthermore, determine which way your swing direction (either right or left), as well as measure the width of your jambs.
To take measurements accurately, first remove any trim or brickmould from the rough opening. Once you can gain access to the frame, use a pry bar to take measurements – measuring three places along each jamb width and height and recording their largest measurements as your door frame width and height respectively.
Measure Your Walls
Before you can size a pre-hung door correctly, you must first get an accurate measurement of its rough opening. To do so, carefully remove the interior casing around both door and frame using a pry bar without damaging walls or damaging other objects in the room.
Once the old casing is removed, measure from stud to stud along the bottom frame on both sides and record its smallest height as this will become the basis of your new door and jamb sizes.
Additionally, measure the depth of the wall jamb (part that connects drywall). If this measurement is uneven, shimming may be necessary in order to equalize any gaps that exist between it and drywall.
Cut the Jambs
After setting up the frame, make sure it’s centered in its opening and square across both sides; if not, adjust by using shims until it does so.
If the casing rests flush against the frame, use 8d finish nails through its header stud and trimmer stud to secure it to the wall. If the frame is off balance, place a shim at its hinge locations behind the casing as additional support.
Once the frame has been secured, use a level to assess both jambs and door itself for uniform reveal reveals, making any necessary shimming adjustments as necessary to bring frame and door plumb. Check also that hinge side for evenness of reveal.
Install the Jambs
Utilizing an accurate level and tape measure, create a uniform 1/8-inch gap between the door frame and framing. Regularly check and test the door to ensure it swings freely without becoming stuck or jamming on either the floor or top of its frame.
Shim the hinge side of your frame so it sits flush with the drywall (if your opening was framed with drywall). Slip a level underneath shims at one corner, adjust until its bubble is in the center, and secure with finish nails before repeating this process at other hinge locations.
Hang the Door
Pre-hung doors make installing doors much simpler for homeowners who may not have experience installing hinges, lock sets or door knobs themselves. Installing such an entry can take just one trip to their garage!
Use a level or plumb bob to check that wall and trimmer studs are plumb, then adjust hinge side of frame until it is plumb while filling gaps on latch side of frame.
Place a 4-foot level on the floor in your doorway. If its bubble is lower on one hinge side than another, slip some shims beneath it until the frame meets with the wall levelly and secure them securely with tape or nail gun nails. Tack shims in place.
Pre-hung doors are all-inclusive units that include the frame, slab with cutout for doorknob and hinges required to assemble it – much simpler to install than slab doors that require mortices, hinges and handles to be fitted separately and assembled individually.
Use a level to ensure the doorway is square and that the door has an even reveal. Check that the hinge side jamb is lower than the latch side jamb; if necessary shim the jambs to level them out and make sure the door swings freely and closes easily while its top and striker also have an equal reveal gap.