Installing a pre-hung door in your house can be one of the most satisfying home improvement projects you’ll ever undertake, yet it can be tricky. To ensure a proper job is completed, you will require both a large level and wooden shims for this endeavor.
Start by checking the jack stud on the hinge side of your frame with a level and making any necessary shim adjustments so it is level. If any framing elements are off level, use shims until everything is level again.
Removing an Existing Door
Installing a new front door into an existing frame is an undertaking that can have immediate effects on curb appeal, energy efficiency and security. While DIY options exist for this job, professional services often need to be brought in to get optimal results.
Start by taking apart and removing the old door and trim. Next, inspect its frame for signs of rusting, rotting or leaks; use wood shims if needed to adjust it if necessary – ideally the top edge should be level with both floor surface and hinge mortises on wall – before using wood shims to level and level out its height ideally using wooden shims as necessary – although you could always opt for more expensive wood treatments instead if desired.
When purchasing a prehung door, be sure to provide your rough opening measurements to the salesperson so they can ensure you purchase one that will fit. Otherwise, they may suggest purchasing a “slab door,” a plain door without jambs or lockset holes drilled. Many home centers and lumberyards provide these slab doors.
Prepping the Opening
Once the old door has been removed, you are ready to install your new frame. Begin by checking the opening with a level, to ensure it is square and plumb; if not, add shims on hinge side of jamb legs until it is. Also inspect jack studs (the interior studs on either side of header) using both levels and shims until it reaches plumbness.
Next, dry-fit the new door into its opening. Since it can be heavy to maneuver into place, enlist the assistance of someone to assist. Make sure it shuts properly without gaps at the top or bottom before nailing through shims into head jamb studs using 8d finish nails; additionally shim trimmer studs where casing will rest against them to plumb them out; finally nail through casing into studs using 8d finish nails before fastening in place with drywall screws.
Hanging the Door
Once your pre-hung door has been cut and fitted to fit its new space, it’s time to hang it! First, make sure the hinge side jamb is level with the wall – use a framing square or straight piece of wood as a scrap to ensure it sits square with your wall surface.
Start by placing a four-foot level on the bottom of the hinge side jamb, making any necessary shimming adjustments until its bubble aligns perfectly with the trimmer stud. Do the same on the latch side.
As doors can be heavy, have someone assist with this step if necessary. Once your frame is plumb and secure with 8d finish nails through shims and trimmer stud into wall, nail 8d finish nails through casing at hinge locations using 8d finish nails so as to stop movement of frame after hanging door.
Finishing the Job
Pre-hung doors make most of the hard work easy for you. Still, this heavy and difficult task should only be undertaken by those with basic carpentry experience alone and may require basic carpentry tools for installation.
Your rough opening should be one to two inches larger than the dimensions of the door unit itself to allow for adjustments during installation and to facilitate level-and-plumb alignment of your new interior door. This extra room gives you room to shim the door into its proper alignment for smooth functioning.
Once all shims have been attached to the frame with nails, nail the trim directly to it using finish nails at 12-inch intervals. Test that the door is square by opening and closing it; if not, use additional trim shimming as necessary before re-nailing to correct. Next install your lockset, trim around its outside edge, install doorknob, hardware, trim exterior trim etc.