A Quick Guide To Installing Prehung Doors In Bedrooms

Replacing a bedroom door with a prehung door is a moderately challenging DIY project that requires some carpentry skills and tools. Prehung doors are advantageous as they come with the door already attached to the frame, making installation more straightforward than traditional doors. This guide will cover the steps to replace a bedroom door with a prehung door.

First, it is important to understand the difference between a prehung door and a slab door. A prehung door is a complete unit with the door, slab, and hinges ready for installation, whereas a slab door only includes the door itself, requiring separate hinge and frame installation.

To replace a bedroom door with a prehung door, follow these steps:

1. Remove the existing door and jambs: Take out the old door, hinge pins, hinge plates, strike plate, and loosen the trim with a putty knife. Carefully pry away the side jambs and head jamb.

2. Measure the rough opening: Ensure the opening is 1-2 inches larger than the prehung door to allow for adjustments.

3. Set the prehung door into the opening: Slide the prehung door into the rough opening, ensuring it is centred and the jamb is flush with the wall.

4. Stabilize the hinge side of the door: Check that the hinge side of the door is plumb (vertically straight) and stabilize it by adding shims to both sides near the top.

5. Secure the hinge side jamb: Nail into the jamb at the shimmed areas, ensuring the door remains centred and plumb.

6. Level the door: Close the door and check that the top portion is level. Adjust by shimming the latch side as needed to achieve a uniform reveal (gap between the door and jamb).

7. Line up and secure the latch side jamb: Bring the jamb on the latch side flush with the adjacent drywall, ensuring a 1/8-inch reveal. Nail through the jamb where you have shimmed.

8. Secure the top jamb and test the door: Put nails through the top jamb and previously nailed shims. Test the door to ensure it swings freely and closes properly.

By following these steps and paying attention to detail, you can successfully replace your bedroom door with a prehung door, achieving a professional-looking result.

Removing the old door and jambs

Loosen the trim with a stiff putty knife. Be careful not to damage the wall. If the trim is in good condition, you can reuse it with the new prehung door.

Remove the door from its hinges using a screwdriver or drill to take out the hinge pins. Set the door aside.

Take out the hinge plates and the strike plate from the door frame.

Remove any trim or moulding around the door frame using a utility knife. Score along the edges of the trim to prevent damage to the wall when prying it off.

Take out the old door frame. Cut through any nails or screws attaching the frame to the wall using a reciprocating saw. Clean up any debris or protruding nails left behind.

Check for plumb and square. Use a level to check if the wall and floor are level. If the hinge side of the wall is lower than the latch side, slip shims underneath until the level is even. Tack the shims to the floor with finish nails.

Remove the old door jambs. Carefully pry the side jambs away from the studs and then pry down the head jamb. You can pull the jambs apart, but it is easier to leave them connected and remove them as one piece.

Measuring the rough opening

Step 1: Remove Interior Moulding

Start by removing any interior moulding or trim surrounding the old door. Use a wide, flat pry bar to gently pry away the moulding from the door jamb. This step will expose the rough opening, which is the structural frame that surrounds the door.

Step 2: Measure the Rough Opening Height

To measure the height of the rough opening, you will need a measuring tape. Measure from the bottom of the threshold nose (the piece of wood or stone at the bottom of the door) to the bottom of the rough opening header (the top of the door frame). Take measurements at the centre and both sides of the opening, and record the smallest value. This smallest measurement will be your rough opening height.

Step 3: Measure the Rough Opening Width

Next, you will measure the width of the rough opening. Using your measuring tape, take measurements at the centre, top, and bottom edges of the opening. Record the smallest measurement as the rough opening width. It is important to take multiple measurements as older homes may have settled, resulting in slight variations.

Step 4: Check for Plumb and Square

Use a level to check if the sides of the rough opening are plumb (vertical). While the sides may not be perfectly vertical, they should be close enough to allow adequate room for the new door. Also, check if the opening is square by measuring diagonally from corner to corner in both directions. If the diagonal measurements are equal, the opening is square.

Step 5: Consider Flooring and Wall Thickness

If you plan to install new flooring, consider its thickness when measuring the height of the rough opening. This adjustment will ensure the new door clears the new floor surface. Additionally, evaluate the thickness of the wall framing, as it can affect the choice of door jambs. Standard interior walls are typically framed with 2 x 4 or 2 x 6 studs.

Step 6: Verify Measurements

It is crucial to verify your measurements to ensure an accurate fit for your new prehung door. Re-check all your measurements and make necessary adjustments. Remember that the rough opening should be slightly larger than the door to allow for adjustments and accommodate variations in wall framing.

Setting the door into the rough opening

Now that you've prepared the rough opening and removed the old door and jambs, it's time to set the new prehung door into place. Here's a step-by-step guide:

• Slide the prehung door into the rough opening: Carefully lift the prehung door assembly and slide it into the opening. Make sure it sits pretty flush and close in the hole. You may need an extra pair of hands for this step, especially if you're dealing with a solid core door.
• Brace the door: Open the door 90 degrees from the frame and shim under it to prevent it from falling. Adjust the shims so that the top of the frame is sitting flush with the drywall.
• Mount the hinge side of the frame: Install shims above the top hinge, between the frame and the stud. Ensure the shims are placed in a way that creates an even thickness. Adjust the shims to remove any gaps and create a snug fit.
• Secure the hinge side: Use a small straight edge to ensure the frame is flush with the drywall. You can use a brad nailer with 2" nails or a drill, countersink bit, and screws for this step. Drive 2-3 nails on each side of the door stop, going through the shims to keep them in place.
• Shim and secure the rest of the hinge side: Move down the door and install the center and bottom shims in the same way as the top. Adjust the shims as needed to ensure the door frame is level and plumb. Then, attach the hinge side to the stud.
• Close the door and confirm: Remove the shims from below the door and slowly close it. Keep an eye on the gaps and listen for any binding. The top and striker sides should have an even reveal gap.
• Attach the striker side: Slide shims into place on the top striker side, referencing the door to ensure an even reveal (the gap between the frame and door). Make adjustments as needed. Once you're happy with the alignment, attach the striker side to the stud.
• Shim and secure the bottom of the striker side: If there's a gap between the shims and the frame, apply pressure to the frame to close the gap. Nail the frame to the stud and make any necessary adjustments to ensure a perfect gap.

At this point, the door should be mounted and standing in place. You can now proceed with the finishing touches, such as caulking, sealing, and painting.

Stabilizing the door and securing the hinge side jamb

First, ensure that the hinge side of the door is plumb, or perfectly vertical. You can use a level to check if the door is plumb and make adjustments if needed.

Next, stabilize the door by adding shims to both sides of the hinge side jamb, near the top. Shims are tapered pieces of wood that help fill gaps and create an even thickness. Make sure to install the shims with the tapered ends facing opposite directions to ensure an even thickness. Adjust the shims so that they fill any gaps but do not cause the door frame to twist or become uneven.

Once the shims are in place, use a small straight edge, such as another shim, to ensure that the frame is flush with the drywall. Then, use a nail gun or drill to secure the shims and the hinge side jamb to the stud. Fire a few nails or screws on each side of the door stop, going through the shims to keep them in place and prevent the frame from bowing.

After securing the top part of the hinge side jamb, move down the door and install the center and bottom shims in the same way. Just above the hinges, place the shims snugly, ensuring there is no play when you shake the hinges side to side. Check the door frame with a level and make any necessary adjustments.

Finally, attach the hinge side jamb to the stud by nailing or screwing through the shims, working from the middle to the bottom.

Levelling the door to ensure it will swing freely

Levelling the door is crucial to ensure it swings freely and closes securely without sticking or sitting too loosely in the frame. Here are some detailed steps to help you achieve this:

Step 1: Check the Level of the Door

Use a level to check if the door is plumb, or perfectly vertical. This step is essential to ensure the door functions properly and does not bind or swing open on its own. You can use a level or a plumb bob for this task.

Step 2: Adjust the Shims

If the door is not level, you may need to adjust the shims. Shims are thin, wedge-shaped pieces of material placed between the door frame and the wall to fill gaps and create a snug fit. You can use cedar or composite shims, which are commonly available.

Place shims at the hinge locations, ensuring that about half of each shim is above the hinge. This will provide support and help keep the door in place. You may also need to shim the latch side of the door at roughly the same height as the hinges.

Step 3: Fine-Tune the Reveal

The reveal is the horizontal gap between the top of the door and the head jamb. It should be uniform from left to right and maintain a consistent gap of about 1/8" to 3/16". If the reveal is not uniform, you may need to adjust it by pushing up the head casing or making minor adjustments to the shims.

Step 4: Check the Vertical Reveal

Check the vertical reveal between the door and the jamb on the latch side. This gap should be about the thickness of a nickel (approximately 1/8"). If it is not consistent, you may need to adjust the casing and move the jamb by hand. Ensure that the leading edge of the door clears the jamb by a consistent amount (approximately 1/8") when opened.

Step 5: Test the Door

Open and close the door to ensure it swings freely and stays in place at various positions. If the door swings on its own, you may need to adjust the shims or ensure that the frame is plumb. Check that the door closes smoothly and latches properly.

Step 6: Shim the Latch Side

Slip a pair of shims between the main jamb on the latch side and the trimmer, near the top of the door opening. Nail them in place when they are just touching the back of the jamb without putting any pressure on it.

Step 7: Shim the Bottom of the Door

Place additional shims a few inches above the base of the jamb to provide support and prevent the jamb from flexing. You should also shim just above and below the strike plate to ensure a secure fit.

By carefully following these steps and making any necessary adjustments, you will be able to level your prehung door, ensuring it swings freely and functions smoothly.

Frequently asked questions