Before beginning installation of your pre-hung door, gather several essential tools and supplies – wood shims and finish nails are musts!
Noting how and where your door swings is known as handedness. Additionally, make sure the opening is generally plumb since buildings can settle over time causing inconsistencies that you can correct with ease.
Measure the Rough Opening
If you are replacing an existing door, measuring its rough opening will help determine what size prehung door is necessary. Although this process can be complicated, a few simple steps should help make this easier for you.
At first, remove any interior trim around the doorway before taking measurements from stud to stud at both center and lowest points of opening.
Record these measurements, then head out to your local hardware store.
Cut the Jambs
Use a framing square and plumb bob to check that the new head jamb is plumb and level, as necessary removing interior casing exposing frame studs; and shim the jambs as necessary to straighten them and ensure they remain level.
Install a 4-foot level in the doorway. If one side of its bubble falls below another, place shims under it until it reads plumb and adjust accordingly.
Install the Jambs
Prehung doors come from the factory with their door frame (known as a jamb) slightly too long; it’s simple and straightforward to make any necessary corrections.
Make sure that the door frame is plumb (or vertical). Shim the hinge side as needed.
Before nailing in additional pairs of shims to stabilize and protect the frame from flexing as the door opens or closes, nail additional pairs on both the latch side of the frame as well as above and below the strike plate to prevent it from flexing with each door swing. This should help to stabilize it further.
Shim the Door
Shims make installing prehung doors simple. A level will help make sure that their jambs are parallel with both walls and plumb.
Begin on the hinge side, adding shims until the jamb is flush with the wall. Next, move onto the latch side and repeat.
Once finished, use a utility knife to score and snap off each shim carefully so as to not damage the door.
Install the Hinges
Once the hinge side of the jamb is fitted with precision, switch over to installing its latch side strike plate and doorknob. Check the gap at the base between frame and wall by using a level.
Shim the top and bottom edges of each trim piece so that half is situated above the hinge, and half above the latch. Nail them securely to the frame and studs, before using a level or plumb bob to assess gaps between pieces.
Install the Door
Installing your new door is an effortless way to completely transform the appearance of your home, just be sure to create a level, plumb, and square opening when installing it.
Prehung doors feature doorknob cutouts, frames and hinges – making installation much simpler than slab doors. Be sure to have help available as these heavy doors may need some adjustments; use shims under each head jamb if it is out of plumb before leveling them out using side jamb shims if necessary.
Install the Hardware
Utilizing a level and tape measure, inspect the hinge side of your door frame for levelness and plumb. Shim as necessary until your frame is square.
Experienced carpenters should be able to install a prehung door within an hour, but if not, consider hiring a professional for assistance; door installation contractors in your area can be found here. When installing, evaluate which side the door swings.
Finish the Job
Installing a pre-hung door requires help from another person due to its weight and difficulty of movement. Once mounted, add its hardware (doorknob and lockset).
A slab door is defined as any solid or hollow core door without frames or hinges, while pre-hung doors come pre-mounted with everything needed for assembly, including cutouts for doorknobs and all necessary hardware. They may require some assembly expertise but should not be difficult for anyone with basic carpentry skills to install successfully.