DIY home renovations: How to install a prehung door

Replacing or installing a new door in your home requires a lot of patience and a certain amount of skill. This is because once installed, the door needs to be able to latch effortlessly into place, swing easily on its hinges, and clear its side jambs.

If you need to replace a door in your home, consider installing a prehung door. Prehung doors come with their own frames, making sure they function optimally. Follow these instructions on how to install a prehung door to learn how to achieve the perfect fit.

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The tools

Here’s a list of the tools you will need to install a prehung door.

1. A knife or a blade
2. Shims
3. A reciprocating saw
4. A brad nailer
5. Multi-purpose tool
6. An electric drill
7. 3-inch screws
8. 4-foot level
9. A framing square

The process

Removing the old door

1. Start by removing the trim. To do this, run a knife or blade along the side of the trim, or the door paneling as we know it. This will loosen the trim, enabling you to remove it.
2. Make sure you do this on either side of the door. Removing the trim will give you access to the door jamb.
3. Unscrew the hinges and remove the door.

Read more: Prehung vs slab door

Removing the jamb and threshold

1. To remove the jamb, use a reciprocating saw and cut the jamb in half. Remove the pieces.
2. There are usually screws anchoring the jamb to the house. Make sure you remove them. You ought to find them near where the door hinges usually are or near the strike plate.
3. Some doors have metal thresholds. Make sure you remove those as well. If they are present.

Read more: How to lubricate door hinges

Checking levels

1. Place a 4-foot level on the floor in the doorway. 
2. If you find the hinge side to be at a lower level than the latch side, adjust levels by slipping a shin under the level closest to the hinge jamb. Make adjustments until the level is centered.
3. Use a finish nail to attach the shims to the floor. You will not need to use shims if the level is lower on the latch side.
4. Use a door plumb or a level to check the walls and trimmer studs. While you’re at it, use a framing square to make sure the trimmers’ faces are square to the wall.
5. Measure between the trimmers at the top, middle and bottom to make sure they are parallel.

Read more: How to cut door hinges

Dry fitting the door

1. Fit the new prehung door into the rough opening of the door frame to see if the size is right.
2. If you find any of the sides of the frame are too long, you will need to measure how many inches are extra and cut the frame using a multipurpose tool to make adjustments.
3. If the door needs support to be lifted into the proper position, insert shims at the bottom of the door frame.

Making the door frame plumb and level

1. You will need to check how vertically straight and horizontally straight the hinge side of the door is. 
2. See how far from vertically straight the hinge side of the door is to know how much adjustment using shims is needed.
3. Set your four-foot level against the jamb on the hinge side like a straightedge. You will need to insert a shim between the drywall and jamb wherever you notice gaps. This will straighten the jamb and close the gap.
4. Once the door and the jamb on the hinge side are plumb, use a brad nailer to secure the shims to the jamb with a couple of nails.

Read more: Patching plaster walls

Making the reveal consistent

1. The reveal is the gaps between the door and the frame. You will need to make sure this gap is consistent all the way around the door, including where the doorknob is (the strike side) as well as the top of the door.
2. If you notice any inconsistencies, first check the hinge side again to make sure it is plumb.
3. Next, start from the top of the door towards the bottom and insert shims along the strike side of the door to make the reveal between the door and the frame consistent.
4. As you work your way down, pay attention to reinforce the area above and below the strike plate.
5. Once again, use a brad nailer to secure the shims in place. Remove extra shims.
6. If you need to make adjustments to the door stop or the jamb, use a woodblock and a hammer to gently tap them in the right direction.
7. You will also need to check the reveal on the top of the door. Once again, insert shims wherever you notice the gap is not level. Use a brad nailer to secure the shims and remove the excess.

Read more: How to stop air from leaking around a door?

Testing the door

Swing the door to double-check that it swings freely without any obstructions.

Read more: Fix a loose wooden door frame

Installing the door trim

1. Decide how far back you want the trim from the jamb, and mark that distance all the way around the jamb.
2. Measure the marked corners, and make a mitered joint cut at a 45-degree angle of the trim to make sure the angled cuts line up at the corner of the door trim. 
3. Install the trim header piece first. Secure it using a brad nailer.
4. Determine the measurement of the trim of both sides of the door using the points at the header section.
5. Cut the needed measurement of the trim and install using a brad nailer. 
6. Make sure the reveals between the trim and the door jamb are consistent.

Read more: Cased opening

Finishing the project

Finally, install the doorknob and the strike plate. Your new pre-hung door is now installed.

Read more: Loose door knobs

Why DIY?

A prehung door could cost anywhere between $60 and more than $600, depending on the material and the finish you choose. If you’d like to pay a professional to install your exterior or interior door for you, basic labor costs could put you down between $145 and $235 for two hours. Considering this home improvement project will take between 4 to 6 hours to complete, doing it yourself could save you more than $800.

Read more: Wood door maintenance

Written by Narayan Shrouthy. December 21, 2021

Narayan is a content writer for Kukun. With experience in both content writing and editing, Narayan mixes his writing and love for reading with his passion for music. As an active musician, He aims to be a key player in Kukun's content experience.

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xavier.chavez1@outlook.es(@xavier-chavez1outlook-es)

I think this is a good project for doing with my kids, I never thought in that, but the money you say can be saved helped me make my decision