Pre-hung doors make setting and aligning them much simpler by including all necessary hardware within one unit, making installation quicker and ensuring it remains plumb and level.
But pre-hung doors can be heavy and cumbersome to transport alone, requiring assistance from friends or partners to help. To save yourself the effort of maneuvering them alone, enlist the aid of someone willing to assist – perhaps their helper would even benefit as they assist each other!
Measure the Opening
Before installing a pre-hung door, it is essential to take accurate measurements of both its frame and rough opening to ensure a perfect fit for your new door. Accurate measurements will help to make installation smoother and alleviate any frustration during its assembly.
To measure an opening, first remove the interior casing using a putty knife and pry bar. This will reveal the rough opening frame; measure its width from one stud to the next before noting your measurement.
Start by measuring the height from the floor or subfloor to the top of the header, taking measurements at three points and using the largest of them as your final height for your new door – add two inches for frames and shimming!
Remove the Existing Door
Before installing a new door, it’s essential that the existing frame is level. If it isn’t, simply shim the jambs until they are aligned accordingly.
To remove an existing door, first pry off its casing with a flat pry bar. Next, loosen its hinge pins before carefully pulling out. Take care with its heavy weight; use a drop cloth as protection.
If your new door is too tall for its current frame, a circular saw can easily trim it to size. If it is too short, wood shims can fill any gaps to ensure uniform opening across your entire frame for prehung doors, making sure they swing open and closed smoothly while also protecting against water damage to frames.
Install the Jambs
Before fastening the jambs, verify that the new door is centered in its opening and level and plumb. Use a 4-foot level to assess alignment before shimming hinge-side jamb until its bubble falls between lines on the floor.
Shim the latch-side jamb similarly, nailing through these shims into the studs for a clean reveal when installing casing later.
Once your frame is flush with the wall, nail blocks to each side to hold it until drywall can be completed and you can remove these temporary supports. Shim the door slab until its stops on either side are tight enough against them to prevent swinging through an open frame.
Install the Door
Once the shims are installed, it’s time to install the door. Begin at its hinge side with help from someone nearby for support before working your way upwards towards its center.
Prior to driving in the final screw on the latch side, first check for door plumb by placing a carpenter’s level on the sill. If it is out of plumb, add more shims on latch side and secure them using finish nails if necessary.
Once your top is flush with the studs, apply a bead of caulk around the door jamb to protect the exterior trim and avoid water damage to walls. This will provide added protection to these important components of your project.
Finishing Touches
No matter whether you’re building from scratch or installing pre-hung doors into existing frames, starting off right requires having the appropriate tools. A kit of wood shims and 4d, 6d or 8d finish nails as well as trim pieces specific to your prehung door should be at the forefront of your mind when choosing tools and supplies for installation.
Before placing the door into place, use a carpenter’s level to check it is level and plumb.
If it’s not, use shims as needed to raise the side jambs until they are level with the wall and use nails and caulk as recommended by your door manufacturer. Once complete, hammer in nails as directed.