Swapping out a tired hollow-core door for a solid new one instantly upgrades a room, and it is one of the most satisfying weekend projects a homeowner can take on. Interior door replacement falls into two very different jobs depending on whether you reuse the existing frame or replace the whole unit. Understanding that distinction up front decides how hard the project will be, how much it costs, and how long it takes.
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A basic slab swap into a good frame takes an afternoon and costs $40 to $150 for the door. A full prehung replacement, frame and all, runs $150 to $500 per opening and demands more carpentry, but it fixes racked or out-of-square jambs that no amount of slab tuning will cure.
- Slab Versus Prehung: Choosing Your Approach
- Measuring for a Replacement Door
- Tools and Materials You Will Need
- Replacing a Slab Door Step by Step
- Installing a Prehung Door
- Choosing the Right Door Style and Material
- Fixing Common Fit Problems
- Costs, Timelines, and When to Hire Out
- Matching Trim and Hardware
- Soundproofing and Privacy Upgrades
- When You Replace Bedroom Doors: Privacy, Airflow, and Batch-Planning Tips
- Final Tips for a Professional Result
Slab Versus Prehung: Choosing Your Approach
A slab door is just the door panel with no frame or hinges attached. Choose a slab when your existing jamb is straight, the hinges are solid, and the door simply looks dated or was damaged. You will transfer the hinge mortises and bore the knob hole to match, which requires care but saves money.
A prehung door arrives already mounted in its own frame with hinges and the latch bore cut. Pick a prehung unit when the jamb is warped, the wall is out of plumb, or the door has never closed right. Replacing the whole assembly guarantees a square, smooth-swinging result even in an old house with settled framing.
Measuring for a Replacement Door
Accurate measurements prevent the most expensive mistake in any interior door replacement, which is ordering the wrong size. Standard interior doors come in widths of 24, 28, 30, 32, and 36 inches, with a standard height of 80 inches.
- For a slab, measure the width and height of the old door itself, not the opening.
- Note the door thickness, typically 1-3/8 inches for interior doors.
- Check the hinge count and spacing so the new slab matches.
- Confirm the swing direction: stand in the opening with hinges on your side to determine left- or right-hand.
- For a prehung, measure the rough opening, which should be about two inches wider and 2-1/2 inches taller than the door.
Write these numbers down and take them to the store. A door that is a half inch too wide can sometimes be trimmed, but one that is too small means starting over.
Tools and Materials You Will Need
Assemble your kit before you pull the old door. A few specialty items make the difference between a clean install and a frustrating one.
- Drill with a hinge-mortise or chisel set, plus a 2-1/8-inch hole saw for the knob
- Level, tape measure, and a carpenter’s square
- Wood shims and 8d finish nails or a nail gun
- Utility knife and a sharp chisel for hinge mortises
- Screwdriver, hammer, and safety glasses
- Caulk and paintable wood filler for finishing
Replacing a Slab Door Step by Step
Reusing the frame keeps this job simple. The key is transferring the hardware locations precisely from the old door to the new one.
- Lift the old door off its hinges by tapping the hinge pins up and out.
- Lay the old and new doors side by side, matching the top and hinge edge.
- Mark the hinge and knob locations from the old door onto the new slab.
- Chisel the hinge mortises to depth, then bore the knob and latch holes with the hole saw.
- Attach the hinges, hang the door on the frame, and slide the pins home.
- Check the swing, then plane the strike edge lightly if it binds.
Test the fit before drilling the latch. You want an even reveal, about 1/8 inch, around the top and sides so the door does not stick when humidity rises.
Installing a Prehung Door
A prehung install is more involved because you are setting a new frame plumb and level in a rough opening. Remove the old unit by prying off the trim and backing out the jamb screws, then set the new assembly in place.
Shim behind each hinge and the strike side until the jamb is perfectly plumb, checking with a level on both faces. Nail through the jamb and shims into the framing, close the door to confirm an even reveal, and only then trim the shims flush. Reinstall or replace the casing, caulk the gaps, and fill nail holes before painting.
Choosing the Right Door Style and Material
Beyond slab versus prehung, the look and construction of the door shape both the feel of the room and the price. The most common panel styles are flat-slab modern, two-panel shaker, and traditional six-panel, each setting a distinct tone.
Material matters just as much as style. A hollow-core door has a cardboard honeycomb interior and weighs very little, which keeps costs low but offers poor sound blocking. A solid-core door fills that cavity with a dense composite, giving it real heft and muffling noise, which makes it worth the extra $50 to $120 for bedrooms and bathrooms. Solid wood doors are the premium choice, beautiful and heavy, but they expand and contract with humidity and cost the most. For most homes, solid-core molded doors deliver the best balance of quiet, durability, and value.
Fixing Common Fit Problems
Even a well-chosen door can bind, rub, or fail to latch once hung, and knowing the quick fixes saves a service call. A door that sticks along the top or latch edge usually needs a light pass with a hand plane or a few strokes of coarse sandpaper on the high spot.
If the door swings open or closed on its own, the frame is out of plumb; a common trick is to remove one hinge screw and drive a longer 3-inch screw into the framing to pull the jamb back into alignment. When the latch will not catch, the strike plate is likely misaligned. Close the door, mark where the latch hits the plate, and either file the strike opening slightly or reposition the plate a fraction of an inch. These small adjustments turn a frustrating door into one that closes with a satisfying click.
Costs, Timelines, and When to Hire Out
Budget realistically. A solid-core slab runs $70 to $200 for better sound control, while a hollow-core builder door costs $40 to $80. Prehung units range from $120 for a basic six-panel to over $500 for a solid MDF or wood door with premium hardware. Hardware, hinges, and knob sets add $20 to $80.
A confident DIYer replaces a slab in two to three hours and a prehung in three to five. If you have six doors to do, expect a full weekend. Hiring a carpenter typically costs $100 to $300 in labor per opening, more for out-of-square framing that needs correction.
Matching Trim and Hardware
A new door looks unfinished if the trim and hardware do not tie into the rest of the house. Casing, the molding that frames the door, comes in dozens of profiles, and matching the existing style keeps the room cohesive.
Take a short offcut of your existing casing to the home center to find a matching profile, or replace all the casing in a room at once if the old trim is dated or damaged. Hardware finish matters just as much; pick knobs, levers, and hinges in a single consistent finish, whether satin nickel, matte black, or oil-rubbed bronze, and carry that finish through the room for a pulled-together look. Standard hinges come in a 3.5-inch size for interior doors with either square or radius corners, so match the corner style to your existing hinge mortises to avoid re-chiseling. These small coordination choices are what make a DIY door swap look professionally done.
Soundproofing and Privacy Upgrades
If your main reason for replacing a door is noise, a few targeted upgrades go well beyond simply choosing a solid-core slab. Sound travels through gaps as easily as through the door itself, so sealing the perimeter matters as much as the door’s mass.
Add adhesive foam weatherstripping around the jamb and a door sweep or automatic drop-down seal along the bottom to close the gap where most sound leaks through. A solid-core door paired with these seals dramatically cuts noise transfer into bedrooms, home offices, and bathrooms. For a nursery or a media room where quiet is paramount, an acoustic-rated door with a higher sound transmission class blocks even more, though it costs $200 to $500. Combining a heavier door with good perimeter sealing delivers most of the benefit at a fraction of the price of a specialty acoustic door.
When You Replace Bedroom Doors: Privacy, Airflow, and Batch-Planning Tips
Bedrooms are the rooms where homeowners most often swap doors, usually to get more quiet, better privacy, or a style that matches a remodel. The general steps above apply, but bedroom doors come with a few specific decisions that are easy to overlook until the new door is already hanging.
Pick the Right Lockset
Bedroom doors normally get a privacy lockset: a push-button or turn-button lock on the inside and a small emergency release hole on the outside. Unlocking it only takes a thin pin or the tool that comes in the box. Avoid keyed entry locks on bedroom doors, especially children’s rooms, because a lost key turns a locked door into an emergency. If you’re changing hardware finishes throughout the house, buy all the bedroom privacy sets at once so the finishes match exactly.
Don’t Starve the Room of Airflow
Many homes have a supply vent in each bedroom but only one central return air grille in a hallway. Those bedrooms depend on the gap under the door to let air flow back to the system. The soundproofing section above recommends sweeps and drop-down seals, and they work well in rooms with their own return. But fully sealing a bedroom that lacks a return can leave it stuffy, harder to heat and cool, and louder from air pressure. Before adding a tight bottom seal, check for a return grille in the room. If there isn’t one, keep a modest gap under the door, or ask an HVAC contractor about a transfer grille or jumper duct.
Plan Several Doors as One Project
- Measure every opening separately. Bedroom and closet doors in the same hallway are often different widths, and older homes may not have standard sizes.
- Record the swing direction for each door on a simple floor sketch so you order the correct left- and right-hand units.
- Check the flooring height. New carpet or thicker flooring can make a new door drag. Measure from the finished floor, and trim the bottom if needed.
- Order one extra lockset and set of hinges in case a part arrives damaged.
Older Homes: Test Before You Plane
If your house was built before 1978, the old doors and trim may carry lead paint. Planing, sanding, or scraping them releases hazardous dust. Test with an EPA-recognized lead test kit before trimming original doors or casing. If the test is positive, remove the parts whole instead of sanding in place, or hire a lead-safe certified contractor.
Final Tips for a Professional Result
Prime and paint the door before hanging it whenever possible, including the top and bottom edges, to seal against moisture and prevent warping. Use a solid-core door for bedrooms and bathrooms where sound privacy matters, and save hollow-core for closets to keep costs down.
Done carefully, an interior door replacement pays back far beyond its modest cost, sharpening the look of a room and eliminating the daily annoyance of a door that sticks, rattles, or refuses to latch. Measure twice, take your time on the hinges, and you will have a door that swings true for decades.
